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Index: linux-2.6.32.21/kernel/sched_bfs.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.32.21/kernel/sched_bfs.c 2010-08-29 12:01:04.537683189 +1000
@@ -0,0 +1,6664 @@
+/*
+ * kernel/sched_bfs.c, was sched.c
+ *
+ * Kernel scheduler and related syscalls
+ *
+ * Copyright (C) 1991-2002 Linus Torvalds
+ *
+ * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
+ * make semaphores SMP safe
+ * 1998-11-19 Implemented schedule_timeout() and related stuff
+ * by Andrea Arcangeli
+ * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
+ * hybrid priority-list and round-robin design with
+ * an array-switch method of distributing timeslices
+ * and per-CPU runqueues. Cleanups and useful suggestions
+ * by Davide Libenzi, preemptible kernel bits by Robert Love.
+ * 2003-09-03 Interactivity tuning by Con Kolivas.
+ * 2004-04-02 Scheduler domains code by Nick Piggin
+ * 2007-04-15 Work begun on replacing all interactivity tuning with a
+ * fair scheduling design by Con Kolivas.
+ * 2007-05-05 Load balancing (smp-nice) and other improvements
+ * by Peter Williams
+ * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
+ * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
+ * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
+ * Thomas Gleixner, Mike Kravetz
+ * now Brainfuck deadline scheduling policy by Con Kolivas deletes
+ * a whole lot of those previous things.
+ */
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/nmi.h>
+#include <linux/init.h>
+#include <asm/uaccess.h>
+#include <linux/highmem.h>
+#include <linux/smp_lock.h>
+#include <asm/mmu_context.h>
+#include <linux/interrupt.h>
+#include <linux/capability.h>
+#include <linux/completion.h>
+#include <linux/kernel_stat.h>
+#include <linux/debug_locks.h>
+#include <linux/perf_event.h>
+#include <linux/security.h>
+#include <linux/notifier.h>
+#include <linux/profile.h>
+#include <linux/freezer.h>
+#include <linux/vmalloc.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+#include <linux/threads.h>
+#include <linux/timer.h>
+#include <linux/rcupdate.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/cpumask.h>
+#include <linux/percpu.h>
+#include <linux/kthread.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/syscalls.h>
+#include <linux/times.h>
+#include <linux/tsacct_kern.h>
+#include <linux/kprobes.h>
+#include <linux/delayacct.h>
+#include <linux/log2.h>
+#include <linux/bootmem.h>
+#include <linux/ftrace.h>
+
+#include <asm/tlb.h>
+#include <asm/unistd.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/sched.h>
+
+#define rt_prio(prio) unlikely((prio) < MAX_RT_PRIO)
+#define rt_task(p) rt_prio((p)->prio)
+#define rt_queue(rq) rt_prio((rq)->rq_prio)
+#define batch_task(p) (unlikely((p)->policy == SCHED_BATCH))
+#define is_rt_policy(policy) ((policy) == SCHED_FIFO || \
+ (policy) == SCHED_RR)
+#define has_rt_policy(p) unlikely(is_rt_policy((p)->policy))
+#define idleprio_task(p) unlikely((p)->policy == SCHED_IDLEPRIO)
+#define iso_task(p) unlikely((p)->policy == SCHED_ISO)
+#define iso_queue(rq) unlikely((rq)->rq_policy == SCHED_ISO)
+#define ISO_PERIOD ((5 * HZ * num_online_cpus()) + 1)
+
+/*
+ * Convert user-nice values [ -20 ... 0 ... 19 ]
+ * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
+ * and back.
+ */
+#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
+#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
+#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
+
+/*
+ * 'User priority' is the nice value converted to something we
+ * can work with better when scaling various scheduler parameters,
+ * it's a [ 0 ... 39 ] range.
+ */
+#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
+#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
+#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
+#define SCHED_PRIO(p) ((p)+MAX_RT_PRIO)
+
+/* Some helpers for converting to/from various scales.*/
+#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
+#define MS_TO_NS(TIME) ((TIME) * 1000000)
+#define MS_TO_US(TIME) ((TIME) * 1000)
+
+/*
+ * This is the time all tasks within the same priority round robin.
+ * Value is in ms and set to a minimum of 6ms. Scales with number of cpus.
+ * Tunable via /proc interface.
+ */
+int rr_interval __read_mostly = 6;
+
+/*
+ * sched_iso_cpu - sysctl which determines the cpu percentage SCHED_ISO tasks
+ * are allowed to run five seconds as real time tasks. This is the total over
+ * all online cpus.
+ */
+int sched_iso_cpu __read_mostly = 70;
+
+/*
+ * The relative length of deadline for each priority(nice) level.
+ */
+static int prio_ratios[PRIO_RANGE] __read_mostly;
+
+/*
+ * The quota handed out to tasks of all priority levels when refilling their
+ * time_slice.
+ */
+static inline unsigned long timeslice(void)
+{
+ return MS_TO_US(rr_interval);
+}
+
+/*
+ * The global runqueue data that all CPUs work off. All data is protected
+ * by grq.lock.
+ */
+struct global_rq {
+ spinlock_t lock;
+ unsigned long nr_running;
+ unsigned long nr_uninterruptible;
+ unsigned long long nr_switches;
+ struct list_head queue[PRIO_LIMIT];
+ DECLARE_BITMAP(prio_bitmap, PRIO_LIMIT + 1);
+ int iso_ticks;
+ int iso_refractory;
+#ifdef CONFIG_SMP
+ unsigned long qnr; /* queued not running */
+ cpumask_t cpu_idle_map;
+#endif
+};
+
+/* There can be only one */
+static struct global_rq grq;
+
+/*
+ * This is the main, per-CPU runqueue data structure.
+ * This data should only be modified by the local cpu.
+ */
+struct rq {
+#ifdef CONFIG_SMP
+#ifdef CONFIG_NO_HZ
+ unsigned char in_nohz_recently;
+#endif
+#endif
+
+ struct task_struct *curr, *idle;
+ struct mm_struct *prev_mm;
+
+ /* Stored data about rq->curr to work outside grq lock */
+ unsigned long rq_deadline;
+ unsigned int rq_policy;
+ int rq_time_slice;
+ u64 rq_last_ran;
+ int rq_prio;
+
+ /* Accurate timekeeping data */
+ u64 timekeep_clock;
+ unsigned long user_pc, nice_pc, irq_pc, softirq_pc, system_pc,
+ iowait_pc, idle_pc;
+ atomic_t nr_iowait;
+
+#ifdef CONFIG_SMP
+ int cpu; /* cpu of this runqueue */
+ int online;
+
+ struct root_domain *rd;
+ struct sched_domain *sd;
+ unsigned long *cpu_locality; /* CPU relative cache distance */
+#ifdef CONFIG_SCHED_SMT
+ int (*siblings_idle)(unsigned long cpu);
+ /* See if all smt siblings are idle */
+ cpumask_t smt_siblings;
+#endif
+#ifdef CONFIG_SCHED_MC
+ int (*cache_idle)(unsigned long cpu);
+ /* See if all cache siblings are idle */
+ cpumask_t cache_siblings;
+#endif
+#endif
+
+ u64 clock;
+#ifdef CONFIG_SCHEDSTATS
+
+ /* latency stats */
+ struct sched_info rq_sched_info;
+ unsigned long long rq_cpu_time;
+ /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
+
+ /* sys_sched_yield() stats */
+ unsigned int yld_count;
+
+ /* schedule() stats */
+ unsigned int sched_switch;
+ unsigned int sched_count;
+ unsigned int sched_goidle;
+
+ /* try_to_wake_up() stats */
+ unsigned int ttwu_count;
+ unsigned int ttwu_local;
+
+ /* BKL stats */
+ unsigned int bkl_count;
+#endif
+};
+
+static DEFINE_PER_CPU(struct rq, runqueues) ____cacheline_aligned_in_smp;
+static DEFINE_MUTEX(sched_hotcpu_mutex);
+
+#ifdef CONFIG_SMP
+
+/*
+ * We add the notion of a root-domain which will be used to define per-domain
+ * variables. Each exclusive cpuset essentially defines an island domain by
+ * fully partitioning the member cpus from any other cpuset. Whenever a new
+ * exclusive cpuset is created, we also create and attach a new root-domain
+ * object.
+ *
+ */
+struct root_domain {
+ atomic_t refcount;
+ cpumask_var_t span;
+ cpumask_var_t online;
+
+ /*
+ * The "RT overload" flag: it gets set if a CPU has more than
+ * one runnable RT task.
+ */
+ cpumask_var_t rto_mask;
+ atomic_t rto_count;
+#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
+ /*
+ * Preferred wake up cpu nominated by sched_mc balance that will be
+ * used when most cpus are idle in the system indicating overall very
+ * low system utilisation. Triggered at POWERSAVINGS_BALANCE_WAKEUP(2)
+ */
+ unsigned int sched_mc_preferred_wakeup_cpu;
+#endif
+};
+
+/*
+ * By default the system creates a single root-domain with all cpus as
+ * members (mimicking the global state we have today).
+ */
+static struct root_domain def_root_domain;
+#endif
+
+static inline int cpu_of(struct rq *rq)
+{
+#ifdef CONFIG_SMP
+ return rq->cpu;
+#else
+ return 0;
+#endif
+}
+
+/*
+ * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
+ * See detach_destroy_domains: synchronize_sched for details.
+ *
+ * The domain tree of any CPU may only be accessed from within
+ * preempt-disabled sections.
+ */
+#define for_each_domain(cpu, __sd) \
+ for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
+
+#ifdef CONFIG_SMP
+#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
+#define this_rq() (&__get_cpu_var(runqueues))
+#define task_rq(p) cpu_rq(task_cpu(p))
+#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
+#else /* CONFIG_SMP */
+static struct rq *uprq;
+#define cpu_rq(cpu) (uprq)
+#define this_rq() (uprq)
+#define task_rq(p) (uprq)
+#define cpu_curr(cpu) ((uprq)->curr)
+#endif
+#define raw_rq() (&__raw_get_cpu_var(runqueues))
+
+#include "sched_stats.h"
+
+#ifndef prepare_arch_switch
+# define prepare_arch_switch(next) do { } while (0)
+#endif
+#ifndef finish_arch_switch
+# define finish_arch_switch(prev) do { } while (0)
+#endif
+
+/*
+ * All common locking functions performed on grq.lock. rq->clock is local to
+ * the cpu accessing it so it can be modified just with interrupts disabled,
+ * but looking up task_rq must be done under grq.lock to be safe.
+ */
+inline void update_rq_clock(struct rq *rq)
+{
+ rq->clock = sched_clock_cpu(cpu_of(rq));
+}
+
+static inline int task_running(struct task_struct *p)
+{
+ return p->oncpu;
+}
+
+static inline void grq_lock(void)
+ __acquires(grq.lock)
+{
+ spin_lock(&grq.lock);
+}
+
+static inline void grq_unlock(void)
+ __releases(grq.lock)
+{
+ spin_unlock(&grq.lock);
+}
+
+static inline void grq_lock_irq(void)
+ __acquires(grq.lock)
+{
+ spin_lock_irq(&grq.lock);
+}
+
+static inline void time_lock_grq(struct rq *rq)
+ __acquires(grq.lock)
+{
+ update_rq_clock(rq);
+ grq_lock();
+}
+
+static inline void grq_unlock_irq(void)
+ __releases(grq.lock)
+{
+ spin_unlock_irq(&grq.lock);
+}
+
+static inline void grq_lock_irqsave(unsigned long *flags)
+ __acquires(grq.lock)
+{
+ spin_lock_irqsave(&grq.lock, *flags);
+}
+
+static inline void grq_unlock_irqrestore(unsigned long *flags)
+ __releases(grq.lock)
+{
+ spin_unlock_irqrestore(&grq.lock, *flags);
+}
+
+static inline struct rq
+*task_grq_lock(struct task_struct *p, unsigned long *flags)
+ __acquires(grq.lock)
+{
+ grq_lock_irqsave(flags);
+ return task_rq(p);
+}
+
+static inline struct rq
+*time_task_grq_lock(struct task_struct *p, unsigned long *flags)
+ __acquires(grq.lock)
+{
+ struct rq *rq = task_grq_lock(p, flags);
+ update_rq_clock(rq);
+ return rq;
+}
+
+static inline struct rq *task_grq_lock_irq(struct task_struct *p)
+ __acquires(grq.lock)
+{
+ grq_lock_irq();
+ return task_rq(p);
+}
+
+static inline void time_task_grq_lock_irq(struct task_struct *p)
+ __acquires(grq.lock)
+{
+ struct rq *rq = task_grq_lock_irq(p);
+ update_rq_clock(rq);
+}
+
+static inline void task_grq_unlock_irq(void)
+ __releases(grq.lock)
+{
+ grq_unlock_irq();
+}
+
+static inline void task_grq_unlock(unsigned long *flags)
+ __releases(grq.lock)
+{
+ grq_unlock_irqrestore(flags);
+}
+
+/**
+ * grunqueue_is_locked
+ *
+ * Returns true if the global runqueue is locked.
+ * This interface allows printk to be called with the runqueue lock
+ * held and know whether or not it is OK to wake up the klogd.
+ */
+inline int grunqueue_is_locked(void)
+{
+ return spin_is_locked(&grq.lock);
+}
+
+inline void grq_unlock_wait(void)
+ __releases(grq.lock)
+{
+ smp_mb(); /* spin-unlock-wait is not a full memory barrier */
+ spin_unlock_wait(&grq.lock);
+}
+
+static inline void time_grq_lock(struct rq *rq, unsigned long *flags)
+ __acquires(grq.lock)
+{
+ local_irq_save(*flags);
+ time_lock_grq(rq);
+}
+
+static inline struct rq *__task_grq_lock(struct task_struct *p)
+ __acquires(grq.lock)
+{
+ grq_lock();
+ return task_rq(p);
+}
+
+static inline void __task_grq_unlock(void)
+ __releases(grq.lock)
+{
+ grq_unlock();
+}
+
+#ifndef __ARCH_WANT_UNLOCKED_CTXSW
+static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
+{
+}
+
+static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
+ /* this is a valid case when another task releases the spinlock */
+ grq.lock.owner = current;
+#endif
+ /*
+ * If we are tracking spinlock dependencies then we have to
+ * fix up the runqueue lock - which gets 'carried over' from
+ * prev into current:
+ */
+ spin_acquire(&grq.lock.dep_map, 0, 0, _THIS_IP_);
+
+ grq_unlock_irq();
+}
+
+#else /* __ARCH_WANT_UNLOCKED_CTXSW */
+
+static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
+{
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+ grq_unlock_irq();
+#else
+ grq_unlock();
+#endif
+}
+
+static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
+{
+ smp_wmb();
+#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+ local_irq_enable();
+#endif
+}
+#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
+
+/*
+ * A task that is queued but not running will be on the grq run list.
+ * A task that is not running or queued will not be on the grq run list.
+ * A task that is currently running will have ->oncpu set but not on the
+ * grq run list.
+ */
+static inline int task_queued(struct task_struct *p)
+{
+ return (!list_empty(&p->run_list));
+}
+
+/*
+ * Removing from the global runqueue. Enter with grq locked.
+ */
+static void dequeue_task(struct task_struct *p)
+{
+ list_del_init(&p->run_list);
+ if (list_empty(grq.queue + p->prio))
+ __clear_bit(p->prio, grq.prio_bitmap);
+}
+
+/*
+ * When a task is freshly forked, the first_time_slice flag is set to say
+ * it has taken time_slice from its parent and if it exits on this first
+ * time_slice it can return its time_slice back to the parent.
+ */
+static inline void reset_first_time_slice(struct task_struct *p)
+{
+ if (unlikely(p->first_time_slice))
+ p->first_time_slice = 0;
+}
+
+/*
+ * To determine if it's safe for a task of SCHED_IDLEPRIO to actually run as
+ * an idle task, we ensure none of the following conditions are met.
+ */
+static int idleprio_suitable(struct task_struct *p)
+{
+ return (!freezing(p) && !signal_pending(p) &&
+ !(task_contributes_to_load(p)) && !(p->flags & (PF_EXITING)));
+}
+
+/*
+ * To determine if a task of SCHED_ISO can run in pseudo-realtime, we check
+ * that the iso_refractory flag is not set.
+ */
+static int isoprio_suitable(void)
+{
+ return !grq.iso_refractory;
+}
+
+/*
+ * Adding to the global runqueue. Enter with grq locked.
+ */
+static void enqueue_task(struct task_struct *p)
+{
+ if (!rt_task(p)) {
+ /* Check it hasn't gotten rt from PI */
+ if ((idleprio_task(p) && idleprio_suitable(p)) ||
+ (iso_task(p) && isoprio_suitable()))
+ p->prio = p->normal_prio;
+ else
+ p->prio = NORMAL_PRIO;
+ }
+ __set_bit(p->prio, grq.prio_bitmap);
+ list_add_tail(&p->run_list, grq.queue + p->prio);
+ sched_info_queued(p);
+}
+
+/* Only idle task does this as a real time task*/
+static inline void enqueue_task_head(struct task_struct *p)
+{
+ __set_bit(p->prio, grq.prio_bitmap);
+ list_add(&p->run_list, grq.queue + p->prio);
+ sched_info_queued(p);
+}
+
+static inline void requeue_task(struct task_struct *p)
+{
+ sched_info_queued(p);
+}
+
+/*
+ * Returns the relative length of deadline all compared to the shortest
+ * deadline which is that of nice -20.
+ */
+static inline int task_prio_ratio(struct task_struct *p)
+{
+ return prio_ratios[TASK_USER_PRIO(p)];
+}
+
+/*
+ * task_timeslice - all tasks of all priorities get the exact same timeslice
+ * length. CPU distribution is handled by giving different deadlines to
+ * tasks of different priorities.
+ */
+static inline int task_timeslice(struct task_struct *p)
+{
+ return (rr_interval * task_prio_ratio(p) / 100);
+}
+
+#ifdef CONFIG_SMP
+/*
+ * qnr is the "queued but not running" count which is the total number of
+ * tasks on the global runqueue list waiting for cpu time but not actually
+ * currently running on a cpu.
+ */
+static inline void inc_qnr(void)
+{
+ grq.qnr++;
+}
+
+static inline void dec_qnr(void)
+{
+ grq.qnr--;
+}
+
+static inline int queued_notrunning(void)
+{
+ return grq.qnr;
+}
+
+/*
+ * The cpu_idle_map stores a bitmap of all the cpus currently idle to
+ * allow easy lookup of whether any suitable idle cpus are available.
+ */
+static inline void set_cpuidle_map(unsigned long cpu)
+{
+ cpu_set(cpu, grq.cpu_idle_map);
+}
+
+static inline void clear_cpuidle_map(unsigned long cpu)
+{
+ cpu_clear(cpu, grq.cpu_idle_map);
+}
+
+static int suitable_idle_cpus(struct task_struct *p)
+{
+ return (cpus_intersects(p->cpus_allowed, grq.cpu_idle_map));
+}
+
+static void resched_task(struct task_struct *p);
+
+#define CPUIDLE_CACHE_BUSY (1)
+#define CPUIDLE_DIFF_CPU (2)
+#define CPUIDLE_THREAD_BUSY (4)
+#define CPUIDLE_DIFF_NODE (8)
+
+/*
+ * The best idle CPU is chosen according to the CPUIDLE ranking above where the
+ * lowest value would give the most suitable CPU to schedule p onto next. We
+ * iterate from the last CPU upwards instead of using for_each_cpu_mask so as
+ * to be able to break out immediately if the last CPU is idle. The order works
+ * out to be the following:
+ *
+ * Same core, idle or busy cache, idle threads
+ * Other core, same cache, idle or busy cache, idle threads.
+ * Same node, other CPU, idle cache, idle threads.
+ * Same node, other CPU, busy cache, idle threads.
+ * Same core, busy threads.
+ * Other core, same cache, busy threads.
+ * Same node, other CPU, busy threads.
+ * Other node, other CPU, idle cache, idle threads.
+ * Other node, other CPU, busy cache, idle threads.
+ * Other node, other CPU, busy threads.
+ */
+static void resched_best_idle(struct task_struct *p)
+{
+ unsigned long cpu_tmp, best_cpu, best_ranking;
+ cpumask_t tmpmask;
+ struct rq *rq;
+ int iterate;
+
+ cpus_and(tmpmask, p->cpus_allowed, grq.cpu_idle_map);
+ iterate = cpus_weight(tmpmask);
+ best_cpu = task_cpu(p);
+ /*
+ * Start below the last CPU and work up with next_cpu as the last
+ * CPU might not be idle or affinity might not allow it.
+ */
+ cpu_tmp = best_cpu - 1;
+ rq = cpu_rq(best_cpu);
+ best_ranking = ~0UL;
+
+ do {
+ unsigned long ranking;
+ struct rq *tmp_rq;
+
+ ranking = 0;
+ cpu_tmp = next_cpu(cpu_tmp, tmpmask);
+ if (cpu_tmp >= nr_cpu_ids) {
+ cpu_tmp = -1;
+ cpu_tmp = next_cpu(cpu_tmp, tmpmask);
+ }
+ tmp_rq = cpu_rq(cpu_tmp);
+
+ if (rq->cpu_locality[cpu_tmp]) {
+#ifdef CONFIG_NUMA
+ if (rq->cpu_locality[cpu_tmp] > 1)
+ ranking |= CPUIDLE_DIFF_NODE;
+#endif
+ ranking |= CPUIDLE_DIFF_CPU;
+ }
+#ifdef CONFIG_SCHED_MC
+ if (!(tmp_rq->cache_idle(cpu_tmp)))
+ ranking |= CPUIDLE_CACHE_BUSY;
+#endif
+#ifdef CONFIG_SCHED_SMT
+ if (!(tmp_rq->siblings_idle(cpu_tmp)))
+ ranking |= CPUIDLE_THREAD_BUSY;
+#endif
+ if (ranking < best_ranking) {
+ best_cpu = cpu_tmp;
+ if (ranking <= 1)
+ break;
+ best_ranking = ranking;
+ }
+ } while (--iterate > 0);
+
+ resched_task(cpu_rq(best_cpu)->curr);
+}
+
+static inline void resched_suitable_idle(struct task_struct *p)
+{
+ if (suitable_idle_cpus(p))
+ resched_best_idle(p);
+}
+
+/*
+ * The cpu cache locality difference between CPUs is used to determine how far
+ * to offset the virtual deadline. "One" difference in locality means that one
+ * timeslice difference is allowed longer for the cpu local tasks. This is
+ * enough in the common case when tasks are up to 2* number of CPUs to keep
+ * tasks within their shared cache CPUs only. CPUs on different nodes or not
+ * even in this domain (NUMA) have "3" difference, allowing 4 times longer
+ * deadlines before being taken onto another cpu, allowing for 2* the double
+ * seen by separate CPUs above.
+ * Simple summary: Virtual deadlines are equal on shared cache CPUs, double
+ * on separate CPUs and quadruple in separate NUMA nodes.
+ */
+static inline int
+cache_distance(struct rq *task_rq, struct rq *rq, struct task_struct *p)
+{
+ return rq->cpu_locality[cpu_of(task_rq)] * task_timeslice(p);
+}
+#else /* CONFIG_SMP */
+static inline void inc_qnr(void)
+{
+}
+
+static inline void dec_qnr(void)
+{
+}
+
+static inline int queued_notrunning(void)
+{
+ return grq.nr_running;
+}
+
+static inline void set_cpuidle_map(unsigned long cpu)
+{
+}
+
+static inline void clear_cpuidle_map(unsigned long cpu)
+{
+}
+
+static inline int suitable_idle_cpus(struct task_struct *p)
+{
+ return uprq->curr == uprq->idle;
+}
+
+static inline void resched_suitable_idle(struct task_struct *p)
+{
+}
+
+static inline int
+cache_distance(struct rq *task_rq, struct rq *rq, struct task_struct *p)
+{
+ return 0;
+}
+#endif /* CONFIG_SMP */
+
+/*
+ * activate_idle_task - move idle task to the _front_ of runqueue.
+ */
+static inline void activate_idle_task(struct task_struct *p)
+{
+ enqueue_task_head(p);
+ grq.nr_running++;
+ inc_qnr();
+}
+
+static inline int normal_prio(struct task_struct *p)
+{
+ if (has_rt_policy(p))
+ return MAX_RT_PRIO - 1 - p->rt_priority;
+ if (idleprio_task(p))
+ return IDLE_PRIO;
+ if (iso_task(p))
+ return ISO_PRIO;
+ return NORMAL_PRIO;
+}
+
+/*
+ * Calculate the current priority, i.e. the priority
+ * taken into account by the scheduler. This value might
+ * be boosted by RT tasks as it will be RT if the task got
+ * RT-boosted. If not then it returns p->normal_prio.
+ */
+static int effective_prio(struct task_struct *p)
+{
+ p->normal_prio = normal_prio(p);
+ /*
+ * If we are RT tasks or we were boosted to RT priority,
+ * keep the priority unchanged. Otherwise, update priority
+ * to the normal priority:
+ */
+ if (!rt_prio(p->prio))
+ return p->normal_prio;
+ return p->prio;
+}
+
+/*
+ * activate_task - move a task to the runqueue. Enter with grq locked.
+ */
+static void activate_task(struct task_struct *p, struct rq *rq)
+{
+ update_rq_clock(rq);
+
+ /*
+ * Sleep time is in units of nanosecs, so shift by 20 to get a
+ * milliseconds-range estimation of the amount of time that the task
+ * spent sleeping:
+ */
+ if (unlikely(prof_on == SLEEP_PROFILING)) {
+ if (p->state == TASK_UNINTERRUPTIBLE)
+ profile_hits(SLEEP_PROFILING, (void *)get_wchan(p),
+ (rq->clock - p->last_ran) >> 20);
+ }
+
+ p->prio = effective_prio(p);
+ if (task_contributes_to_load(p))
+ grq.nr_uninterruptible--;
+ enqueue_task(p);
+ grq.nr_running++;
+ inc_qnr();
+}
+
+/*
+ * deactivate_task - If it's running, it's not on the grq and we can just
+ * decrement the nr_running. Enter with grq locked.
+ */
+static inline void deactivate_task(struct task_struct *p)
+{
+ if (task_contributes_to_load(p))
+ grq.nr_uninterruptible++;
+ grq.nr_running--;
+}
+
+#ifdef CONFIG_SMP
+void set_task_cpu(struct task_struct *p, unsigned int cpu)
+{
+ int old_cpu = task_cpu(p);
+
+ trace_sched_migrate_task(p, cpu);
+ if (old_cpu != cpu)
+ perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0);
+
+ /*
+ * After ->cpu is set up to a new value, task_grq_lock(p, ...) can be
+ * successfuly executed on another CPU. We must ensure that updates of
+ * per-task data have been completed by this moment.
+ */
+ smp_wmb();
+ task_thread_info(p)->cpu = cpu;
+}
+#endif
+
+/*
+ * Move a task off the global queue and take it to a cpu for it will
+ * become the running task.
+ */
+static inline void take_task(struct rq *rq, struct task_struct *p)
+{
+ set_task_cpu(p, cpu_of(rq));
+ dequeue_task(p);
+ dec_qnr();
+}
+
+/*
+ * Returns a descheduling task to the grq runqueue unless it is being
+ * deactivated.
+ */
+static inline void return_task(struct task_struct *p, int deactivate)
+{
+ if (deactivate)
+ deactivate_task(p);
+ else {
+ inc_qnr();
+ enqueue_task(p);
+ }
+}
+
+/*
+ * resched_task - mark a task 'to be rescheduled now'.
+ *
+ * On UP this means the setting of the need_resched flag, on SMP it
+ * might also involve a cross-CPU call to trigger the scheduler on
+ * the target CPU.
+ */
+#ifdef CONFIG_SMP
+
+#ifndef tsk_is_polling
+#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
+#endif
+
+static void resched_task(struct task_struct *p)
+{
+ int cpu;
+
+ assert_spin_locked(&grq.lock);
+
+ if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
+ return;
+
+ set_tsk_thread_flag(p, TIF_NEED_RESCHED);
+
+ cpu = task_cpu(p);
+ if (cpu == smp_processor_id())
+ return;
+
+ /* NEED_RESCHED must be visible before we test polling */
+ smp_mb();
+ if (!tsk_is_polling(p))
+ smp_send_reschedule(cpu);
+}
+
+#else
+static inline void resched_task(struct task_struct *p)
+{
+ assert_spin_locked(&grq.lock);
+ set_tsk_need_resched(p);
+}
+#endif
+
+/**
+ * task_curr - is this task currently executing on a CPU?
+ * @p: the task in question.
+ */
+inline int task_curr(const struct task_struct *p)
+{
+ return cpu_curr(task_cpu(p)) == p;
+}
+
+#ifdef CONFIG_SMP
+struct migration_req {
+ struct list_head list;
+
+ struct task_struct *task;
+ int dest_cpu;
+
+ struct completion done;
+};
+
+/*
+ * wait_task_context_switch - wait for a thread to complete at least one
+ * context switch.
+ *
+ * @p must not be current.
+ */
+void wait_task_context_switch(struct task_struct *p)
+{
+ unsigned long nvcsw, nivcsw, flags;
+ int running;
+ struct rq *rq;
+
+ nvcsw = p->nvcsw;
+ nivcsw = p->nivcsw;
+ for (;;) {
+ /*
+ * The runqueue is assigned before the actual context
+ * switch. We need to take the runqueue lock.
+ *
+ * We could check initially without the lock but it is
+ * very likely that we need to take the lock in every
+ * iteration.
+ */
+ rq = task_grq_lock(p, &flags);
+ running = task_running(p);
+ task_grq_unlock(&flags);
+
+ if (likely(!running))
+ break;
+ /*
+ * The switch count is incremented before the actual
+ * context switch. We thus wait for two switches to be
+ * sure at least one completed.
+ */
+ if ((p->nvcsw - nvcsw) > 1)
+ break;
+ if ((p->nivcsw - nivcsw) > 1)
+ break;
+
+ cpu_relax();
+ }
+}
+
+/*
+ * wait_task_inactive - wait for a thread to unschedule.
+ *
+ * If @match_state is nonzero, it's the @p->state value just checked and
+ * not expected to change. If it changes, i.e. @p might have woken up,
+ * then return zero. When we succeed in waiting for @p to be off its CPU,
+ * we return a positive number (its total switch count). If a second call
+ * a short while later returns the same number, the caller can be sure that
+ * @p has remained unscheduled the whole time.
+ *
+ * The caller must ensure that the task *will* unschedule sometime soon,
+ * else this function might spin for a *long* time. This function can't
+ * be called with interrupts off, or it may introduce deadlock with
+ * smp_call_function() if an IPI is sent by the same process we are
+ * waiting to become inactive.
+ */
+unsigned long wait_task_inactive(struct task_struct *p, long match_state)
+{
+ unsigned long flags;
+ int running, on_rq;
+ unsigned long ncsw;
+ struct rq *rq;
+
+ for (;;) {
+ /*
+ * We do the initial early heuristics without holding
+ * any task-queue locks at all. We'll only try to get
+ * the runqueue lock when things look like they will
+ * work out! In the unlikely event rq is dereferenced
+ * since we're lockless, grab it again.
+ */
+#ifdef CONFIG_SMP
+retry_rq:
+ rq = task_rq(p);
+ if (unlikely(!rq))
+ goto retry_rq;
+#else /* CONFIG_SMP */
+ rq = task_rq(p);
+#endif
+ /*
+ * If the task is actively running on another CPU
+ * still, just relax and busy-wait without holding
+ * any locks.
+ *
+ * NOTE! Since we don't hold any locks, it's not
+ * even sure that "rq" stays as the right runqueue!
+ * But we don't care, since this will return false
+ * if the runqueue has changed and p is actually now
+ * running somewhere else!
+ */
+ while (task_running(p) && p == rq->curr) {
+ if (match_state && unlikely(p->state != match_state))
+ return 0;
+ cpu_relax();
+ }
+
+ /*
+ * Ok, time to look more closely! We need the grq
+ * lock now, to be *sure*. If we're wrong, we'll
+ * just go back and repeat.
+ */
+ rq = task_grq_lock(p, &flags);
+ trace_sched_wait_task(rq, p);
+ running = task_running(p);
+ on_rq = task_queued(p);
+ ncsw = 0;
+ if (!match_state || p->state == match_state)
+ ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
+ task_grq_unlock(&flags);
+
+ /*
+ * If it changed from the expected state, bail out now.
+ */
+ if (unlikely(!ncsw))
+ break;
+
+ /*
+ * Was it really running after all now that we
+ * checked with the proper locks actually held?
+ *
+ * Oops. Go back and try again..
+ */
+ if (unlikely(running)) {
+ cpu_relax();
+ continue;
+ }
+
+ /*
+ * It's not enough that it's not actively running,
+ * it must be off the runqueue _entirely_, and not
+ * preempted!
+ *
+ * So if it was still runnable (but just not actively
+ * running right now), it's preempted, and we should
+ * yield - it could be a while.
+ */
+ if (unlikely(on_rq)) {
+ schedule_timeout_uninterruptible(1);
+ continue;
+ }
+
+ /*
+ * Ahh, all good. It wasn't running, and it wasn't
+ * runnable, which means that it will never become
+ * running in the future either. We're all done!
+ */
+ break;
+ }
+
+ return ncsw;
+}
+
+/***
+ * kick_process - kick a running thread to enter/exit the kernel
+ * @p: the to-be-kicked thread
+ *
+ * Cause a process which is running on another CPU to enter
+ * kernel-mode, without any delay. (to get signals handled.)
+ *
+ * NOTE: this function doesnt have to take the runqueue lock,
+ * because all it wants to ensure is that the remote task enters
+ * the kernel. If the IPI races and the task has been migrated
+ * to another CPU then no harm is done and the purpose has been
+ * achieved as well.
+ */
+void kick_process(struct task_struct *p)
+{
+ int cpu;
+
+ preempt_disable();
+ cpu = task_cpu(p);
+ if ((cpu != smp_processor_id()) && task_curr(p))
+ smp_send_reschedule(cpu);
+ preempt_enable();
+}
+EXPORT_SYMBOL_GPL(kick_process);
+#endif
+
+/**
+ * kthread_bind - bind a just-created kthread to a cpu.
+ * @p: thread created by kthread_create().
+ * @cpu: cpu (might not be online, must be possible) for @k to run on.
+ *
+ * Description: This function is equivalent to set_cpus_allowed(),
+ * except that @cpu doesn't need to be online, and the thread must be
+ * stopped (i.e., just returned from kthread_create()).
+ *
+ * Function lives here instead of kthread.c because it messes with
+ * scheduler internals which require locking.
+ */
+void kthread_bind(struct task_struct *p, unsigned int cpu)
+ {
+ unsigned long flags;
+
+ /* Must have done schedule() in kthread() before we set_task_cpu */
+ if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
+ WARN_ON(1);
+ return;
+ }
+
+ grq_lock_irqsave(&flags);
+ set_task_cpu(p, cpu);
+ p->cpus_allowed = cpumask_of_cpu(cpu);
+ p->flags |= PF_THREAD_BOUND;
+ grq_unlock_irqrestore(&flags);
+}
+EXPORT_SYMBOL(kthread_bind);
+
+#define rq_idle(rq) ((rq)->rq_prio == PRIO_LIMIT)
+#define task_idle(p) ((p)->prio == PRIO_LIMIT)
+
+/*
+ * RT tasks preempt purely on priority. SCHED_NORMAL tasks preempt on the
+ * basis of earlier deadlines. SCHED_BATCH, ISO and IDLEPRIO don't preempt
+ * between themselves, they cooperatively multitask. An idle rq scores as
+ * prio PRIO_LIMIT so it is always preempted. latest_deadline and
+ * highest_prio_rq are initialised only to silence the compiler. When
+ * all else is equal, still prefer this_rq.
+ */
+#ifdef CONFIG_SMP
+static void try_preempt(struct task_struct *p, struct rq *this_rq)
+{
+ struct rq *highest_prio_rq = this_rq;
+ unsigned long latest_deadline, cpu;
+ int highest_prio;
+ cpumask_t tmp;
+
+ if (suitable_idle_cpus(p)) {
+ resched_best_idle(p);
+ return;
+ }
+
+ cpus_and(tmp, cpu_online_map, p->cpus_allowed);
+ latest_deadline = 0;
+ highest_prio = -1;
+
+ for_each_cpu_mask(cpu, tmp) {
+ unsigned long offset_deadline;
+ struct rq *rq;
+ int rq_prio;
+
+ rq = cpu_rq(cpu);
+ rq_prio = rq->rq_prio;
+ if (rq_prio < highest_prio)
+ continue;
+
+ offset_deadline = rq->rq_deadline -
+ cache_distance(this_rq, rq, p);
+
+ if (rq_prio > highest_prio ||
+ (time_after(offset_deadline, latest_deadline) ||
+ (offset_deadline == latest_deadline && this_rq == rq))) {
+ latest_deadline = offset_deadline;
+ highest_prio = rq_prio;
+ highest_prio_rq = rq;
+ }
+ }
+
+ if (p->prio > highest_prio || (p->prio == highest_prio &&
+ p->policy == SCHED_NORMAL && !time_before(p->deadline, latest_deadline)))
+ return;
+
+ /* p gets to preempt highest_prio_rq->curr */
+ resched_task(highest_prio_rq->curr);
+ return;
+}
+#else /* CONFIG_SMP */
+static void try_preempt(struct task_struct *p, struct rq *this_rq)
+{
+ if (p->prio < uprq->rq_prio ||
+ (p->prio == uprq->rq_prio && p->policy == SCHED_NORMAL &&
+ time_before(p->deadline, uprq->rq_deadline)))
+ resched_task(uprq->curr);
+ return;
+}
+#endif /* CONFIG_SMP */
+
+/**
+ * task_oncpu_function_call - call a function on the cpu on which a task runs
+ * @p: the task to evaluate
+ * @func: the function to be called
+ * @info: the function call argument
+ *
+ * Calls the function @func when the task is currently running. This might
+ * be on the current CPU, which just calls the function directly
+ */
+void task_oncpu_function_call(struct task_struct *p,
+ void (*func) (void *info), void *info)
+{
+ int cpu;
+
+ preempt_disable();
+ cpu = task_cpu(p);
+ if (task_curr(p))
+ smp_call_function_single(cpu, func, info, 1);
+ preempt_enable();
+}
+
+/***
+ * try_to_wake_up - wake up a thread
+ * @p: the to-be-woken-up thread
+ * @state: the mask of task states that can be woken
+ * @sync: do a synchronous wakeup?
+ *
+ * Put it on the run-queue if it's not already there. The "current"
+ * thread is always on the run-queue (except when the actual
+ * re-schedule is in progress), and as such you're allowed to do
+ * the simpler "current->state = TASK_RUNNING" to mark yourself
+ * runnable without the overhead of this.
+ *
+ * returns failure only if the task is already active.
+ */
+static int try_to_wake_up(struct task_struct *p, unsigned int state,
+ int wake_flags)
+{
+ int sync, success = 0;
+ unsigned long flags;
+ struct rq *rq;
+
+ get_cpu();
+
+ /* This barrier is undocumented, probably for p->state? くそ */
+ smp_wmb();
+
+ /*
+ * No need to do time_lock_grq as we only need to update the rq clock
+ * if we activate the task
+ */
+ rq = task_grq_lock(p, &flags);
+
+ /* state is a volatile long, どã.ã.てã.å..ã.ã..なã. */
+ if (!((unsigned int)p->state & state))
+ goto out_unlock;
+
+ if (task_queued(p) || task_running(p))
+ goto out_running;
+
+ activate_task(p, rq);
+ sync = wake_flags & WF_SYNC;
+
+ /*
+ * Sync wakeups (i.e. those types of wakeups where the waker
+ * has indicated that it will leave the CPU in short order)
+ * don't trigger a preemption if there are no idle cpus,
+ * instead waiting for current to deschedule.
+ */
+ if (!sync || suitable_idle_cpus(p))
+ try_preempt(p, rq);
+ success = 1;
+
+out_running:
+ trace_sched_wakeup(rq, p, success);
+ p->state = TASK_RUNNING;
+out_unlock:
+ task_grq_unlock(&flags);
+ put_cpu();
+
+ return success;
+}
+
+/**
+ * wake_up_process - Wake up a specific process
+ * @p: The process to be woken up.
+ *
+ * Attempt to wake up the nominated process and move it to the set of runnable
+ * processes. Returns 1 if the process was woken up, 0 if it was already
+ * running.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
+ */
+int wake_up_process(struct task_struct *p)
+{
+ return try_to_wake_up(p, TASK_ALL, 0);
+}
+EXPORT_SYMBOL(wake_up_process);
+
+int wake_up_state(struct task_struct *p, unsigned int state)
+{
+ return try_to_wake_up(p, state, 0);
+}
+
+/*
+ * Perform scheduler related setup for a newly forked process p.
+ * p is forked by current.
+ */
+void sched_fork(struct task_struct *p, int clone_flags)
+{
+ int cpu = get_cpu();
+ struct rq *rq;
+
+#ifdef CONFIG_PREEMPT_NOTIFIERS
+ INIT_HLIST_HEAD(&p->preempt_notifiers);
+#endif
+ /*
+ * We mark the process as running here, but have not actually
+ * inserted it onto the runqueue yet. This guarantees that
+ * nobody will actually run it, and a signal or other external
+ * event cannot wake it up and insert it on the runqueue either.
+ */
+ p->state = TASK_RUNNING;
+ set_task_cpu(p, cpu);
+
+ /* Should be reset in fork.c but done here for ease of bfs patching */
+ p->sched_time = p->stime_pc = p->utime_pc = 0;
+
+ /*
+ * Revert to default priority/policy on fork if requested.
+ */
+ if (unlikely(p->sched_reset_on_fork)) {
+ if (p->policy == SCHED_FIFO || p->policy == SCHED_RR) {
+ p->policy = SCHED_NORMAL;
+ p->normal_prio = normal_prio(p);
+ }
+
+ if (PRIO_TO_NICE(p->static_prio) < 0) {
+ p->static_prio = NICE_TO_PRIO(0);
+ p->normal_prio = p->static_prio;
+ }
+
+ /*
+ * We don't need the reset flag anymore after the fork. It has
+ * fulfilled its duty:
+ */
+ p->sched_reset_on_fork = 0;
+ }
+
+ /*
+ * Make sure we do not leak PI boosting priority to the child.
+ */
+ p->prio = current->normal_prio;
+
+ INIT_LIST_HEAD(&p->run_list);
+#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
+ if (unlikely(sched_info_on()))
+ memset(&p->sched_info, 0, sizeof(p->sched_info));
+#endif
+
+ p->oncpu = 0;
+
+#ifdef CONFIG_PREEMPT
+ /* Want to start with kernel preemption disabled. */
+ task_thread_info(p)->preempt_count = 1;
+#endif
+ if (unlikely(p->policy == SCHED_FIFO))
+ goto out;
+ /*
+ * Share the timeslice between parent and child, thus the
+ * total amount of pending timeslices in the system doesn't change,
+ * resulting in more scheduling fairness. If it's negative, it won't
+ * matter since that's the same as being 0. current's time_slice is
+ * actually in rq_time_slice when it's running.
+ */
+ rq = task_grq_lock_irq(current);
+ if (likely(rq->rq_time_slice > 0)) {
+ rq->rq_time_slice /= 2;
+ /*
+ * The remainder of the first timeslice might be recovered by
+ * the parent if the child exits early enough.
+ */
+ p->first_time_slice = 1;
+ }
+ p->time_slice = rq->rq_time_slice;
+ task_grq_unlock_irq();
+out:
+ put_cpu();
+}
+
+/*
+ * wake_up_new_task - wake up a newly created task for the first time.
+ *
+ * This function will do some initial scheduler statistics housekeeping
+ * that must be done for every newly created context, then puts the task
+ * on the runqueue and wakes it.
+ */
+void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
+{
+ struct task_struct *parent;
+ unsigned long flags;
+ struct rq *rq;
+
+ rq = task_grq_lock(p, &flags); ;
+ parent = p->parent;
+ BUG_ON(p->state != TASK_RUNNING);
+ /* Unnecessary but small chance that the parent changed cpus */
+ set_task_cpu(p, task_cpu(parent));
+ activate_task(p, rq);
+ trace_sched_wakeup_new(rq, p, 1);
+ if (!(clone_flags & CLONE_VM) && rq->curr == parent &&
+ !suitable_idle_cpus(p)) {
+ /*
+ * The VM isn't cloned, so we're in a good position to
+ * do child-runs-first in anticipation of an exec. This
+ * usually avoids a lot of COW overhead.
+ */
+ resched_task(parent);
+ } else
+ try_preempt(p, rq);
+ task_grq_unlock(&flags);
+}
+
+/*
+ * Potentially available exiting-child timeslices are
+ * retrieved here - this way the parent does not get
+ * penalised for creating too many threads.
+ *
+ * (this cannot be used to 'generate' timeslices
+ * artificially, because any timeslice recovered here
+ * was given away by the parent in the first place.)
+ */
+void sched_exit(struct task_struct *p)
+{
+ struct task_struct *parent;
+ unsigned long flags;
+ struct rq *rq;
+
+ if (unlikely(p->first_time_slice)) {
+ int *par_tslice, *p_tslice;
+
+ parent = p->parent;
+ par_tslice = &parent->time_slice;
+ p_tslice = &p->time_slice;
+
+ rq = task_grq_lock(parent, &flags);
+ /* The real time_slice of the "curr" task is on the rq var.*/
+ if (p == rq->curr)
+ p_tslice = &rq->rq_time_slice;
+ else if (parent == task_rq(parent)->curr)
+ par_tslice = &rq->rq_time_slice;
+
+ *par_tslice += *p_tslice;
+ if (unlikely(*par_tslice > timeslice()))
+ *par_tslice = timeslice();
+ task_grq_unlock(&flags);
+ }
+}
+
+#ifdef CONFIG_PREEMPT_NOTIFIERS
+
+/**
+ * preempt_notifier_register - tell me when current is being preempted & rescheduled
+ * @notifier: notifier struct to register
+ */
+void preempt_notifier_register(struct preempt_notifier *notifier)
+{
+ hlist_add_head(&notifier->link, &current->preempt_notifiers);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_register);
+
+/**
+ * preempt_notifier_unregister - no longer interested in preemption notifications
+ * @notifier: notifier struct to unregister
+ *
+ * This is safe to call from within a preemption notifier.
+ */
+void preempt_notifier_unregister(struct preempt_notifier *notifier)
+{
+ hlist_del(&notifier->link);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
+
+static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
+{
+ struct preempt_notifier *notifier;
+ struct hlist_node *node;
+
+ hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
+ notifier->ops->sched_in(notifier, raw_smp_processor_id());
+}
+
+static void
+fire_sched_out_preempt_notifiers(struct task_struct *curr,
+ struct task_struct *next)
+{
+ struct preempt_notifier *notifier;
+ struct hlist_node *node;
+
+ hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
+ notifier->ops->sched_out(notifier, next);
+}
+
+#else /* !CONFIG_PREEMPT_NOTIFIERS */
+
+static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
+{
+}
+
+static void
+fire_sched_out_preempt_notifiers(struct task_struct *curr,
+ struct task_struct *next)
+{
+}
+
+#endif /* CONFIG_PREEMPT_NOTIFIERS */
+
+/**
+ * prepare_task_switch - prepare to switch tasks
+ * @rq: the runqueue preparing to switch
+ * @next: the task we are going to switch to.
+ *
+ * This is called with the rq lock held and interrupts off. It must
+ * be paired with a subsequent finish_task_switch after the context
+ * switch.
+ *
+ * prepare_task_switch sets up locking and calls architecture specific
+ * hooks.
+ */
+static inline void
+prepare_task_switch(struct rq *rq, struct task_struct *prev,
+ struct task_struct *next)
+{
+ fire_sched_out_preempt_notifiers(prev, next);
+ prepare_lock_switch(rq, next);
+ prepare_arch_switch(next);
+}
+
+/**
+ * finish_task_switch - clean up after a task-switch
+ * @rq: runqueue associated with task-switch
+ * @prev: the thread we just switched away from.
+ *
+ * finish_task_switch must be called after the context switch, paired
+ * with a prepare_task_switch call before the context switch.
+ * finish_task_switch will reconcile locking set up by prepare_task_switch,
+ * and do any other architecture-specific cleanup actions.
+ *
+ * Note that we may have delayed dropping an mm in context_switch(). If
+ * so, we finish that here outside of the runqueue lock. (Doing it
+ * with the lock held can cause deadlocks; see schedule() for
+ * details.)
+ */
+static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
+ __releases(grq.lock)
+{
+ struct mm_struct *mm = rq->prev_mm;
+ long prev_state;
+
+ rq->prev_mm = NULL;
+
+ /*
+ * A task struct has one reference for the use as "current".
+ * If a task dies, then it sets TASK_DEAD in tsk->state and calls
+ * schedule one last time. The schedule call will never return, and
+ * the scheduled task must drop that reference.
+ * The test for TASK_DEAD must occur while the runqueue locks are
+ * still held, otherwise prev could be scheduled on another cpu, die
+ * there before we look at prev->state, and then the reference would
+ * be dropped twice.
+ * Manfred Spraul <manfred@colorfullife.com>
+ */
+ prev_state = prev->state;
+ finish_arch_switch(prev);
+ perf_event_task_sched_in(current, cpu_of(rq));
+ finish_lock_switch(rq, prev);
+
+ fire_sched_in_preempt_notifiers(current);
+ if (mm)
+ mmdrop(mm);
+ if (unlikely(prev_state == TASK_DEAD)) {
+ /*
+ * Remove function-return probe instances associated with this
+ * task and put them back on the free list.
+ */
+ kprobe_flush_task(prev);
+ put_task_struct(prev);
+ }
+}
+
+/**
+ * schedule_tail - first thing a freshly forked thread must call.
+ * @prev: the thread we just switched away from.
+ */
+asmlinkage void schedule_tail(struct task_struct *prev)
+ __releases(grq.lock)
+{
+ struct rq *rq = this_rq();
+
+ finish_task_switch(rq, prev);
+#ifdef __ARCH_WANT_UNLOCKED_CTXSW
+ /* In this case, finish_task_switch does not reenable preemption */
+ preempt_enable();
+#endif
+ if (current->set_child_tid)
+ put_user(current->pid, current->set_child_tid);
+}
+
+/*
+ * context_switch - switch to the new MM and the new
+ * thread's register state.
+ */
+static inline void
+context_switch(struct rq *rq, struct task_struct *prev,
+ struct task_struct *next)
+{
+ struct mm_struct *mm, *oldmm;
+
+ prepare_task_switch(rq, prev, next);
+ trace_sched_switch(rq, prev, next);
+ mm = next->mm;
+ oldmm = prev->active_mm;
+ /*
+ * For paravirt, this is coupled with an exit in switch_to to
+ * combine the page table reload and the switch backend into
+ * one hypercall.
+ */
+ arch_start_context_switch(prev);
+
+ if (unlikely(!mm)) {
+ next->active_mm = oldmm;
+ atomic_inc(&oldmm->mm_count);
+ enter_lazy_tlb(oldmm, next);
+ } else
+ switch_mm(oldmm, mm, next);
+
+ if (unlikely(!prev->mm)) {
+ prev->active_mm = NULL;
+ rq->prev_mm = oldmm;
+ }
+ /*
+ * Since the runqueue lock will be released by the next
+ * task (which is an invalid locking op but in the case
+ * of the scheduler it's an obvious special-case), so we
+ * do an early lockdep release here:
+ */
+#ifndef __ARCH_WANT_UNLOCKED_CTXSW
+ spin_release(&grq.lock.dep_map, 1, _THIS_IP_);
+#endif
+
+ /* Here we just switch the register state and the stack. */
+ switch_to(prev, next, prev);
+
+ barrier();
+ /*
+ * this_rq must be evaluated again because prev may have moved
+ * CPUs since it called schedule(), thus the 'rq' on its stack
+ * frame will be invalid.
+ */
+ finish_task_switch(this_rq(), prev);
+}
+
+/*
+ * nr_running, nr_uninterruptible and nr_context_switches:
+ *
+ * externally visible scheduler statistics: current number of runnable
+ * threads, current number of uninterruptible-sleeping threads, total
+ * number of context switches performed since bootup. All are measured
+ * without grabbing the grq lock but the occasional inaccurate result
+ * doesn't matter so long as it's positive.
+ */
+unsigned long nr_running(void)
+{
+ long nr = grq.nr_running;
+
+ if (unlikely(nr < 0))
+ nr = 0;
+ return (unsigned long)nr;
+}
+
+unsigned long nr_uninterruptible(void)
+{
+ long nu = grq.nr_uninterruptible;
+
+ if (unlikely(nu < 0))
+ nu = 0;
+ return nu;
+}
+
+unsigned long long nr_context_switches(void)
+{
+ long long ns = grq.nr_switches;
+
+ /* This is of course impossible */
+ if (unlikely(ns < 0))
+ ns = 1;
+ return (long long)ns;
+}
+
+unsigned long nr_iowait(void)
+{
+ unsigned long i, sum = 0;
+
+ for_each_possible_cpu(i)
+ sum += atomic_read(&cpu_rq(i)->nr_iowait);
+
+ return sum;
+}
+
+unsigned long nr_iowait_cpu(void)
+{
+ struct rq *this = this_rq();
+ return atomic_read(&this->nr_iowait);
+}
+
+unsigned long nr_active(void)
+{
+ return nr_running() + nr_uninterruptible();
+}
+
+/* Fudge this on BFS since load is equal everywhere */
+unsigned long this_cpu_load(void)
+{
+ return nr_active() / num_online_cpus();
+}
+
+/* Variables and functions for calc_load */
+static unsigned long calc_load_update;
+unsigned long avenrun[3];
+EXPORT_SYMBOL(avenrun);
+
+/**
+ * get_avenrun - get the load average array
+ * @loads: pointer to dest load array
+ * @offset: offset to add
+ * @shift: shift count to shift the result left
+ *
+ * These values are estimates at best, so no need for locking.
+ */
+void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
+{
+ loads[0] = (avenrun[0] + offset) << shift;
+ loads[1] = (avenrun[1] + offset) << shift;
+ loads[2] = (avenrun[2] + offset) << shift;
+}
+
+static unsigned long
+calc_load(unsigned long load, unsigned long exp, unsigned long active)
+{
+ load *= exp;
+ load += active * (FIXED_1 - exp);
+ return load >> FSHIFT;
+}
+
+/*
+ * calc_load - update the avenrun load estimates every LOAD_FREQ seconds.
+ */
+void calc_global_load(void)
+{
+ long active;
+
+ if (time_before(jiffies, calc_load_update))
+ return;
+ active = nr_active() * FIXED_1;
+
+ avenrun[0] = calc_load(avenrun[0], EXP_1, active);
+ avenrun[1] = calc_load(avenrun[1], EXP_5, active);
+ avenrun[2] = calc_load(avenrun[2], EXP_15, active);
+
+ calc_load_update = jiffies + LOAD_FREQ;
+}
+
+DEFINE_PER_CPU(struct kernel_stat, kstat);
+
+EXPORT_PER_CPU_SYMBOL(kstat);
+
+/*
+ * On each tick, see what percentage of that tick was attributed to each
+ * component and add the percentage to the _pc values. Once a _pc value has
+ * accumulated one tick's worth, account for that. This means the total
+ * percentage of load components will always be 100 per tick.
+ */
+static void pc_idle_time(struct rq *rq, unsigned long pc)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
+
+ if (atomic_read(&rq->nr_iowait) > 0) {
+ rq->iowait_pc += pc;
+ if (rq->iowait_pc >= 100) {
+ rq->iowait_pc %= 100;
+ cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
+ }
+ } else {
+ rq->idle_pc += pc;
+ if (rq->idle_pc >= 100) {
+ rq->idle_pc %= 100;
+ cpustat->idle = cputime64_add(cpustat->idle, tmp);
+ }
+ }
+}
+
+static void
+pc_system_time(struct rq *rq, struct task_struct *p, int hardirq_offset,
+ unsigned long pc, unsigned long ns)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
+ cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
+
+ p->stime_pc += pc;
+ if (p->stime_pc >= 100) {
+ p->stime_pc -= 100;
+ p->stime = cputime_add(p->stime, cputime_one_jiffy);
+ p->stimescaled = cputime_add(p->stimescaled, one_jiffy_scaled);
+ account_group_system_time(p, cputime_one_jiffy);
+ acct_update_integrals(p);
+ }
+ p->sched_time += ns;
+
+ if (hardirq_count() - hardirq_offset)
+ rq->irq_pc += pc;
+ else if (softirq_count()) {
+ rq->softirq_pc += pc;
+ if (rq->softirq_pc >= 100) {
+ rq->softirq_pc %= 100;
+ cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
+ }
+ } else {
+ rq->system_pc += pc;
+ if (rq->system_pc >= 100) {
+ rq->system_pc %= 100;
+ cpustat->system = cputime64_add(cpustat->system, tmp);
+ }
+ }
+}
+
+static void pc_user_time(struct rq *rq, struct task_struct *p,
+ unsigned long pc, unsigned long ns)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
+ cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
+
+ p->utime_pc += pc;
+ if (p->utime_pc >= 100) {
+ p->utime_pc -= 100;
+ p->utime = cputime_add(p->utime, cputime_one_jiffy);
+ p->utimescaled = cputime_add(p->utimescaled, one_jiffy_scaled);
+ account_group_user_time(p, cputime_one_jiffy);
+ acct_update_integrals(p);
+ }
+ p->sched_time += ns;
+
+ if (TASK_NICE(p) > 0 || idleprio_task(p)) {
+ rq->nice_pc += pc;
+ if (rq->nice_pc >= 100) {
+ rq->nice_pc %= 100;
+ cpustat->nice = cputime64_add(cpustat->nice, tmp);
+ }
+ } else {
+ rq->user_pc += pc;
+ if (rq->user_pc >= 100) {
+ rq->user_pc %= 100;
+ cpustat->user = cputime64_add(cpustat->user, tmp);
+ }
+ }
+}
+
+/* Convert nanoseconds to percentage of one tick. */
+#define NS_TO_PC(NS) (NS * 100 / JIFFIES_TO_NS(1))
+
+/*
+ * This is called on clock ticks and on context switches.
+ * Bank in p->sched_time the ns elapsed since the last tick or switch.
+ * CPU scheduler quota accounting is also performed here in microseconds.
+ * The value returned from sched_clock() occasionally gives bogus values so
+ * some sanity checking is required. Time is supposed to be banked all the
+ * time so default to half a tick to make up for when sched_clock reverts
+ * to just returning jiffies, and for hardware that can't do tsc.
+ */
+static void
+update_cpu_clock(struct rq *rq, struct task_struct *p, int tick)
+{
+ long account_ns = rq->clock - rq->timekeep_clock;
+ struct task_struct *idle = rq->idle;
+ unsigned long account_pc;
+
+ if (unlikely(account_ns < 0))
+ account_ns = 0;
+
+ account_pc = NS_TO_PC(account_ns);
+
+ if (tick) {
+ int user_tick = user_mode(get_irq_regs());
+
+ /* Accurate tick timekeeping */
+ if (user_tick)
+ pc_user_time(rq, p, account_pc, account_ns);
+ else if (p != idle || (irq_count() != HARDIRQ_OFFSET))
+ pc_system_time(rq, p, HARDIRQ_OFFSET,
+ account_pc, account_ns);
+ else
+ pc_idle_time(rq, account_pc);
+ } else {
+ /* Accurate subtick timekeeping */
+ if (p == idle)
+ pc_idle_time(rq, account_pc);
+ else
+ pc_user_time(rq, p, account_pc, account_ns);
+ }
+
+ /* time_slice accounting is done in usecs to avoid overflow on 32bit */
+ if (rq->rq_policy != SCHED_FIFO && p != idle) {
+ long time_diff = rq->clock - rq->rq_last_ran;
+
+ /*
+ * There should be less than or equal to one jiffy worth, and not
+ * negative/overflow. time_diff is only used for internal scheduler
+ * time_slice accounting.
+ */
+ if (unlikely(time_diff <= 0))
+ time_diff = JIFFIES_TO_NS(1) / 2;
+ else if (unlikely(time_diff > JIFFIES_TO_NS(1)))
+ time_diff = JIFFIES_TO_NS(1);
+
+ rq->rq_time_slice -= time_diff / 1000;
+ }
+ rq->rq_last_ran = rq->timekeep_clock = rq->clock;
+}
+
+/*
+ * Return any ns on the sched_clock that have not yet been accounted in
+ * @p in case that task is currently running.
+ *
+ * Called with task_grq_lock() held.
+ */
+static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
+{
+ u64 ns = 0;
+
+ if (p == rq->curr) {
+ update_rq_clock(rq);
+ ns = rq->clock - rq->rq_last_ran;
+ if (unlikely((s64)ns < 0))
+ ns = 0;
+ }
+
+ return ns;
+}
+
+unsigned long long task_delta_exec(struct task_struct *p)
+{
+ unsigned long flags;
+ struct rq *rq;
+ u64 ns;
+
+ rq = task_grq_lock(p, &flags);
+ ns = do_task_delta_exec(p, rq);
+ task_grq_unlock(&flags);
+
+ return ns;
+}
+
+/*
+ * Return accounted runtime for the task.
+ * In case the task is currently running, return the runtime plus current's
+ * pending runtime that have not been accounted yet.
+ */
+unsigned long long task_sched_runtime(struct task_struct *p)
+{
+ unsigned long flags;
+ struct rq *rq;
+ u64 ns;
+
+ rq = task_grq_lock(p, &flags);
+ ns = p->sched_time + do_task_delta_exec(p, rq);
+ task_grq_unlock(&flags);
+
+ return ns;
+}
+
+/*
+ * Return sum_exec_runtime for the thread group.
+ * In case the task is currently running, return the sum plus current's
+ * pending runtime that have not been accounted yet.
+ *
+ * Note that the thread group might have other running tasks as well,
+ * so the return value not includes other pending runtime that other
+ * running tasks might have.
+ */
+unsigned long long thread_group_sched_runtime(struct task_struct *p)
+{
+ struct task_cputime totals;
+ unsigned long flags;
+ struct rq *rq;
+ u64 ns;
+
+ rq = task_grq_lock(p, &flags);
+ thread_group_cputime(p, &totals);
+ ns = totals.sum_exec_runtime + do_task_delta_exec(p, rq);
+ task_grq_unlock(&flags);
+
+ return ns;
+}
+
+/* Compatibility crap for removal */
+void account_user_time(struct task_struct *p, cputime_t cputime,
+ cputime_t cputime_scaled)
+{
+}
+
+void account_idle_time(cputime_t cputime)
+{
+}
+
+/*
+ * Account guest cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in virtual machine since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
+ */
+static void account_guest_time(struct task_struct *p, cputime_t cputime,
+ cputime_t cputime_scaled)
+{
+ cputime64_t tmp;
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+
+ tmp = cputime_to_cputime64(cputime);
+
+ /* Add guest time to process. */
+ p->utime = cputime_add(p->utime, cputime);
+ p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
+ account_group_user_time(p, cputime);
+ p->gtime = cputime_add(p->gtime, cputime);
+
+ /* Add guest time to cpustat. */
+ cpustat->user = cputime64_add(cpustat->user, tmp);
+ cpustat->guest = cputime64_add(cpustat->guest, tmp);
+}
+
+/*
+ * Account system cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @hardirq_offset: the offset to subtract from hardirq_count()
+ * @cputime: the cpu time spent in kernel space since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
+ * This is for guest only now.
+ */
+void account_system_time(struct task_struct *p, int hardirq_offset,
+ cputime_t cputime, cputime_t cputime_scaled)
+{
+
+ if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0))
+ account_guest_time(p, cputime, cputime_scaled);
+}
+
+/*
+ * Account for involuntary wait time.
+ * @steal: the cpu time spent in involuntary wait
+ */
+void account_steal_time(cputime_t cputime)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ cputime64_t cputime64 = cputime_to_cputime64(cputime);
+
+ cpustat->steal = cputime64_add(cpustat->steal, cputime64);
+}
+
+/*
+ * Account for idle time.
+ * @cputime: the cpu time spent in idle wait
+ */
+static void account_idle_times(cputime_t cputime)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ cputime64_t cputime64 = cputime_to_cputime64(cputime);
+ struct rq *rq = this_rq();
+
+ if (atomic_read(&rq->nr_iowait) > 0)
+ cpustat->iowait = cputime64_add(cpustat->iowait, cputime64);
+ else
+ cpustat->idle = cputime64_add(cpustat->idle, cputime64);
+}
+
+#ifndef CONFIG_VIRT_CPU_ACCOUNTING
+
+void account_process_tick(struct task_struct *p, int user_tick)
+{
+}
+
+/*
+ * Account multiple ticks of steal time.
+ * @p: the process from which the cpu time has been stolen
+ * @ticks: number of stolen ticks
+ */
+void account_steal_ticks(unsigned long ticks)
+{
+ account_steal_time(jiffies_to_cputime(ticks));
+}
+
+/*
+ * Account multiple ticks of idle time.
+ * @ticks: number of stolen ticks
+ */
+void account_idle_ticks(unsigned long ticks)
+{
+ account_idle_times(jiffies_to_cputime(ticks));
+}
+#endif
+
+/*
+ * Functions to test for when SCHED_ISO tasks have used their allocated
+ * quota as real time scheduling and convert them back to SCHED_NORMAL.
+ * Where possible, the data is tested lockless, to avoid grabbing grq_lock
+ * because the occasional inaccurate result won't matter. However the
+ * tick data is only ever modified under lock. iso_refractory is only simply
+ * set to 0 or 1 so it's not worth grabbing the lock yet again for that.
+ */
+static void set_iso_refractory(void)
+{
+ grq.iso_refractory = 1;
+}
+
+static void clear_iso_refractory(void)
+{
+ grq.iso_refractory = 0;
+}
+
+/*
+ * Test if SCHED_ISO tasks have run longer than their alloted period as RT
+ * tasks and set the refractory flag if necessary. There is 10% hysteresis
+ * for unsetting the flag.
+ */
+static unsigned int test_ret_isorefractory(struct rq *rq)
+{
+ if (likely(!grq.iso_refractory)) {
+ if (grq.iso_ticks / ISO_PERIOD > sched_iso_cpu)
+ set_iso_refractory();
+ } else {
+ if (grq.iso_ticks / ISO_PERIOD < (sched_iso_cpu * 90 / 100))
+ clear_iso_refractory();
+ }
+ return grq.iso_refractory;
+}
+
+static void iso_tick(void)
+{
+ grq_lock();
+ grq.iso_ticks += 100;
+ grq_unlock();
+}
+
+/* No SCHED_ISO task was running so decrease rq->iso_ticks */
+static inline void no_iso_tick(void)
+{
+ if (grq.iso_ticks) {
+ grq_lock();
+ grq.iso_ticks -= grq.iso_ticks / ISO_PERIOD + 1;
+ if (unlikely(grq.iso_refractory && grq.iso_ticks /
+ ISO_PERIOD < (sched_iso_cpu * 90 / 100)))
+ clear_iso_refractory();
+ grq_unlock();
+ }
+}
+
+static int rq_running_iso(struct rq *rq)
+{
+ return rq->rq_prio == ISO_PRIO;
+}
+
+/* This manages tasks that have run out of timeslice during a scheduler_tick */
+static void task_running_tick(struct rq *rq)
+{
+ struct task_struct *p;
+
+ /*
+ * If a SCHED_ISO task is running we increment the iso_ticks. In
+ * order to prevent SCHED_ISO tasks from causing starvation in the
+ * presence of true RT tasks we account those as iso_ticks as well.
+ */
+ if ((rt_queue(rq) || (iso_queue(rq) && !grq.iso_refractory))) {
+ if (grq.iso_ticks <= (ISO_PERIOD * 100) - 100)
+ iso_tick();
+ } else
+ no_iso_tick();
+
+ if (iso_queue(rq)) {
+ if (unlikely(test_ret_isorefractory(rq))) {
+ if (rq_running_iso(rq)) {
+ /*
+ * SCHED_ISO task is running as RT and limit
+ * has been hit. Force it to reschedule as
+ * SCHED_NORMAL by zeroing its time_slice
+ */
+ rq->rq_time_slice = 0;
+ }
+ }
+ }
+
+ /* SCHED_FIFO tasks never run out of timeslice. */
+ if (rq_idle(rq) || rq->rq_time_slice > 0 || rq->rq_policy == SCHED_FIFO)
+ return;
+
+ /* p->time_slice <= 0. We only modify task_struct under grq lock */
+ p = rq->curr;
+ requeue_task(p);
+ grq_lock();
+ set_tsk_need_resched(p);
+ grq_unlock();
+}
+
+void wake_up_idle_cpu(int cpu);
+
+/*
+ * This function gets called by the timer code, with HZ frequency.
+ * We call it with interrupts disabled. The data modified is all
+ * local to struct rq so we don't need to grab grq lock.
+ */
+void scheduler_tick(void)
+{
+ int cpu = smp_processor_id();
+ struct rq *rq = cpu_rq(cpu);
+
+ sched_clock_tick();
+ update_rq_clock(rq);
+ update_cpu_clock(rq, rq->curr, 1);
+ if (!rq_idle(rq))
+ task_running_tick(rq);
+ else
+ no_iso_tick();
+ perf_event_task_tick(rq->curr, cpu);
+}
+
+notrace unsigned long get_parent_ip(unsigned long addr)
+{
+ if (in_lock_functions(addr)) {
+ addr = CALLER_ADDR2;
+ if (in_lock_functions(addr))
+ addr = CALLER_ADDR3;
+ }
+ return addr;
+}
+
+#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
+ defined(CONFIG_PREEMPT_TRACER))
+void __kprobes add_preempt_count(int val)
+{
+#ifdef CONFIG_DEBUG_PREEMPT
+ /*
+ * Underflow?
+ */
+ if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
+ return;
+#endif
+ preempt_count() += val;
+#ifdef CONFIG_DEBUG_PREEMPT
+ /*
+ * Spinlock count overflowing soon?
+ */
+ DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
+ PREEMPT_MASK - 10);
+#endif
+ if (preempt_count() == val)
+ trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
+}
+EXPORT_SYMBOL(add_preempt_count);
+
+void __kprobes sub_preempt_count(int val)
+{
+#ifdef CONFIG_DEBUG_PREEMPT
+ /*
+ * Underflow?
+ */
+ if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
+ return;
+ /*
+ * Is the spinlock portion underflowing?
+ */
+ if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
+ !(preempt_count() & PREEMPT_MASK)))
+ return;
+#endif
+
+ if (preempt_count() == val)
+ trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
+ preempt_count() -= val;
+}
+EXPORT_SYMBOL(sub_preempt_count);
+#endif
+
+/*
+ * Deadline is "now" in jiffies + (offset by priority). Setting the deadline
+ * is the key to everything. It distributes cpu fairly amongst tasks of the
+ * same nice value, it proportions cpu according to nice level, it means the
+ * task that last woke up the longest ago has the earliest deadline, thus
+ * ensuring that interactive tasks get low latency on wake up. The CPU
+ * proportion works out to the square of the virtual deadline difference, so
+ * this equation will give nice 19 3% CPU compared to nice 0.
+ */
+static inline int prio_deadline_diff(int user_prio)
+{
+ return (prio_ratios[user_prio] * rr_interval * HZ / (1000 * 100)) ? : 1;
+}
+
+static inline int task_deadline_diff(struct task_struct *p)
+{
+ return prio_deadline_diff(TASK_USER_PRIO(p));
+}
+
+static inline int static_deadline_diff(int static_prio)
+{
+ return prio_deadline_diff(USER_PRIO(static_prio));
+}
+
+static inline int longest_deadline_diff(void)
+{
+ return prio_deadline_diff(39);
+}
+
+/*
+ * The time_slice is only refilled when it is empty and that is when we set a
+ * new deadline.
+ */
+static inline void time_slice_expired(struct task_struct *p)
+{
+ reset_first_time_slice(p);
+ p->time_slice = timeslice();
+ p->deadline = jiffies + task_deadline_diff(p);
+}
+
+static inline void check_deadline(struct task_struct *p)
+{
+ if (p->time_slice <= 0)
+ time_slice_expired(p);
+}
+
+/*
+ * O(n) lookup of all tasks in the global runqueue. The real brainfuck
+ * of lock contention and O(n). It's not really O(n) as only the queued,
+ * but not running tasks are scanned, and is O(n) queued in the worst case
+ * scenario only because the right task can be found before scanning all of
+ * them.
+ * Tasks are selected in this order:
+ * Real time tasks are selected purely by their static priority and in the
+ * order they were queued, so the lowest value idx, and the first queued task
+ * of that priority value is chosen.
+ * If no real time tasks are found, the SCHED_ISO priority is checked, and
+ * all SCHED_ISO tasks have the same priority value, so they're selected by
+ * the earliest deadline value.
+ * If no SCHED_ISO tasks are found, SCHED_NORMAL tasks are selected by the
+ * earliest deadline.
+ * Finally if no SCHED_NORMAL tasks are found, SCHED_IDLEPRIO tasks are
+ * selected by the earliest deadline.
+ * Once deadlines are expired (jiffies has passed it) tasks are chosen in FIFO
+ * order. Note that very few tasks will be FIFO for very long because they
+ * only end up that way if they sleep for long or if if there are enough fully
+ * cpu bound tasks to push the load to ~8 higher than the number of CPUs for
+ * nice 0.
+ */
+static inline struct
+task_struct *earliest_deadline_task(struct rq *rq, struct task_struct *idle)
+{
+ unsigned long dl, earliest_deadline = 0; /* Initialise to silence compiler */
+ struct task_struct *p, *edt;
+ unsigned int cpu = cpu_of(rq);
+ struct list_head *queue;
+ int idx = 0;
+
+ edt = idle;
+retry:
+ idx = find_next_bit(grq.prio_bitmap, PRIO_LIMIT, idx);
+ if (idx >= PRIO_LIMIT)
+ goto out;
+ queue = grq.queue + idx;
+ list_for_each_entry(p, queue, run_list) {
+ /* Make sure cpu affinity is ok */
+ if (!cpu_isset(cpu, p->cpus_allowed))
+ continue;
+ if (idx < MAX_RT_PRIO) {
+ /* We found an rt task */
+ edt = p;
+ goto out_take;
+ }
+
+ dl = p->deadline + cache_distance(task_rq(p), rq, p);
+
+ /*
+ * Look for tasks with old deadlines and pick them in FIFO
+ * order, taking the first one found.
+ */
+ if (time_is_before_jiffies(dl)) {
+ edt = p;
+ goto out_take;
+ }
+
+ /*
+ * No rt tasks. Find the earliest deadline task. Now we're in
+ * O(n) territory. This is what we silenced the compiler for:
+ * edt will always start as idle.
+ */
+ if (edt == idle ||
+ time_before(dl, earliest_deadline)) {
+ earliest_deadline = dl;
+ edt = p;
+ }
+ }
+ if (edt == idle) {
+ if (++idx < PRIO_LIMIT)
+ goto retry;
+ goto out;
+ }
+out_take:
+ take_task(rq, edt);
+out:
+ return edt;
+}
+
+/*
+ * Print scheduling while atomic bug:
+ */
+static noinline void __schedule_bug(struct task_struct *prev)
+{
+ struct pt_regs *regs = get_irq_regs();
+
+ printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
+ prev->comm, prev->pid, preempt_count());
+
+ debug_show_held_locks(prev);
+ print_modules();
+ if (irqs_disabled())
+ print_irqtrace_events(prev);
+
+ if (regs)
+ show_regs(regs);
+ else
+ dump_stack();
+}
+
+/*
+ * Various schedule()-time debugging checks and statistics:
+ */
+static inline void schedule_debug(struct task_struct *prev)
+{
+ /*
+ * Test if we are atomic. Since do_exit() needs to call into
+ * schedule() atomically, we ignore that path for now.
+ * Otherwise, whine if we are scheduling when we should not be.
+ */
+ if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
+ __schedule_bug(prev);
+
+ profile_hit(SCHED_PROFILING, __builtin_return_address(0));
+
+ schedstat_inc(this_rq(), sched_count);
+#ifdef CONFIG_SCHEDSTATS
+ if (unlikely(prev->lock_depth >= 0)) {
+ schedstat_inc(this_rq(), bkl_count);
+ schedstat_inc(prev, sched_info.bkl_count);
+ }
+#endif
+}
+
+/*
+ * The currently running task's information is all stored in rq local data
+ * which is only modified by the local CPU, thereby allowing the data to be
+ * changed without grabbing the grq lock.
+ */
+static inline void set_rq_task(struct rq *rq, struct task_struct *p)
+{
+ rq->rq_time_slice = p->time_slice;
+ rq->rq_deadline = p->deadline;
+ rq->rq_last_ran = p->last_ran;
+ rq->rq_policy = p->policy;
+ rq->rq_prio = p->prio;
+}
+
+static void reset_rq_task(struct rq *rq, struct task_struct *p)
+{
+ rq->rq_policy = p->policy;
+ rq->rq_prio = p->prio;
+}
+
+/*
+ * schedule() is the main scheduler function.
+ */
+asmlinkage void __sched schedule(void)
+{
+ struct task_struct *prev, *next, *idle;
+ unsigned long *switch_count;
+ int deactivate, cpu;
+ struct rq *rq;
+
+need_resched:
+ preempt_disable();
+
+ cpu = smp_processor_id();
+ rq = cpu_rq(cpu);
+ idle = rq->idle;
+ rcu_sched_qs(cpu);
+ prev = rq->curr;
+ switch_count = &prev->nivcsw;
+
+ release_kernel_lock(prev);
+need_resched_nonpreemptible:
+
+ deactivate = 0;
+ schedule_debug(prev);
+
+ local_irq_disable();
+ update_rq_clock(rq);
+ update_cpu_clock(rq, prev, 0);
+
+ grq_lock();
+ clear_tsk_need_resched(prev);
+
+ if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
+ if (unlikely(signal_pending_state(prev->state, prev)))
+ prev->state = TASK_RUNNING;
+ else
+ deactivate = 1;
+ switch_count = &prev->nvcsw;
+ }
+
+ if (prev != idle) {
+ /* Update all the information stored on struct rq */
+ prev->time_slice = rq->rq_time_slice;
+ prev->deadline = rq->rq_deadline;
+ check_deadline(prev);
+ return_task(prev, deactivate);
+ /* Task changed affinity off this cpu */
+ if (unlikely(!cpus_intersects(prev->cpus_allowed,
+ cpumask_of_cpu(cpu))))
+ resched_suitable_idle(prev);
+ }
+
+ if (likely(queued_notrunning())) {
+ next = earliest_deadline_task(rq, idle);
+ } else {
+ next = idle;
+ schedstat_inc(rq, sched_goidle);
+ }
+
+ prefetch(next);
+ prefetch_stack(next);
+
+ if (task_idle(next))
+ set_cpuidle_map(cpu);
+ else
+ clear_cpuidle_map(cpu);
+
+ prev->last_ran = rq->clock;
+
+ if (likely(prev != next)) {
+ sched_info_switch(prev, next);
+ perf_event_task_sched_out(prev, next, cpu);
+
+ set_rq_task(rq, next);
+ grq.nr_switches++;
+ prev->oncpu = 0;
+ next->oncpu = 1;
+ rq->curr = next;
+ ++*switch_count;
+
+ context_switch(rq, prev, next); /* unlocks the grq */
+ /*
+ * the context switch might have flipped the stack from under
+ * us, hence refresh the local variables.
+ */
+ cpu = smp_processor_id();
+ rq = cpu_rq(cpu);
+ idle = rq->idle;
+ } else
+ grq_unlock_irq();
+
+ if (unlikely(reacquire_kernel_lock(current) < 0))
+ goto need_resched_nonpreemptible;
+ preempt_enable_no_resched();
+ if (need_resched())
+ goto need_resched;
+}
+EXPORT_SYMBOL(schedule);
+
+#ifdef CONFIG_SMP
+int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
+{
+ unsigned int cpu;
+ struct rq *rq;
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+ /*
+ * Need to access the cpu field knowing that
+ * DEBUG_PAGEALLOC could have unmapped it if
+ * the mutex owner just released it and exited.
+ */
+ if (probe_kernel_address(&owner->cpu, cpu))
+ goto out;
+#else
+ cpu = owner->cpu;
+#endif
+
+ /*
+ * Even if the access succeeded (likely case),
+ * the cpu field may no longer be valid.
+ */
+ if (cpu >= nr_cpumask_bits)
+ goto out;
+
+ /*
+ * We need to validate that we can do a
+ * get_cpu() and that we have the percpu area.
+ */
+ if (!cpu_online(cpu))
+ goto out;
+
+ rq = cpu_rq(cpu);
+
+ for (;;) {
+ /*
+ * Owner changed, break to re-assess state.
+ */
+ if (lock->owner != owner)
+ break;
+
+ /*
+ * Is that owner really running on that cpu?
+ */
+ if (task_thread_info(rq->curr) != owner || need_resched())
+ return 0;
+
+ cpu_relax();
+ }
+out:
+ return 1;
+}
+#endif
+
+#ifdef CONFIG_PREEMPT
+/*
+ * this is the entry point to schedule() from in-kernel preemption
+ * off of preempt_enable. Kernel preemptions off return from interrupt
+ * occur there and call schedule directly.
+ */
+asmlinkage void __sched preempt_schedule(void)
+{
+ struct thread_info *ti = current_thread_info();
+
+ /*
+ * If there is a non-zero preempt_count or interrupts are disabled,
+ * we do not want to preempt the current task. Just return..
+ */
+ if (likely(ti->preempt_count || irqs_disabled()))
+ return;
+
+ do {
+ add_preempt_count(PREEMPT_ACTIVE);
+ schedule();
+ sub_preempt_count(PREEMPT_ACTIVE);
+
+ /*
+ * Check again in case we missed a preemption opportunity
+ * between schedule and now.
+ */
+ barrier();
+ } while (need_resched());
+}
+EXPORT_SYMBOL(preempt_schedule);
+
+/*
+ * this is the entry point to schedule() from kernel preemption
+ * off of irq context.
+ * Note, that this is called and return with irqs disabled. This will
+ * protect us against recursive calling from irq.
+ */
+asmlinkage void __sched preempt_schedule_irq(void)
+{
+ struct thread_info *ti = current_thread_info();
+
+ /* Catch callers which need to be fixed */
+ BUG_ON(ti->preempt_count || !irqs_disabled());
+
+ do {
+ add_preempt_count(PREEMPT_ACTIVE);
+ local_irq_enable();
+ schedule();
+ local_irq_disable();
+ sub_preempt_count(PREEMPT_ACTIVE);
+
+ /*
+ * Check again in case we missed a preemption opportunity
+ * between schedule and now.
+ */
+ barrier();
+ } while (need_resched());
+}
+
+#endif /* CONFIG_PREEMPT */
+
+int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
+ void *key)
+{
+ return try_to_wake_up(curr->private, mode, wake_flags);
+}
+EXPORT_SYMBOL(default_wake_function);
+
+/*
+ * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
+ * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
+ * number) then we wake all the non-exclusive tasks and one exclusive task.
+ *
+ * There are circumstances in which we can try to wake a task which has already
+ * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
+ * zero in this (rare) case, and we handle it by continuing to scan the queue.
+ */
+static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
+ int nr_exclusive, int wake_flags, void *key)
+{
+ struct list_head *tmp, *next;
+
+ list_for_each_safe(tmp, next, &q->task_list) {
+ wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list);
+ unsigned int flags = curr->flags;
+
+ if (curr->func(curr, mode, wake_flags, key) &&
+ (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
+ break;
+ }
+}
+
+/**
+ * __wake_up - wake up threads blocked on a waitqueue.
+ * @q: the waitqueue
+ * @mode: which threads
+ * @nr_exclusive: how many wake-one or wake-many threads to wake up
+ * @key: is directly passed to the wakeup function
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
+ */
+void __wake_up(wait_queue_head_t *q, unsigned int mode,
+ int nr_exclusive, void *key)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&q->lock, flags);
+ __wake_up_common(q, mode, nr_exclusive, 0, key);
+ spin_unlock_irqrestore(&q->lock, flags);
+}
+EXPORT_SYMBOL(__wake_up);
+
+/*
+ * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
+ */
+void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
+{
+ __wake_up_common(q, mode, 1, 0, NULL);
+}
+
+void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
+{
+ __wake_up_common(q, mode, 1, 0, key);
+}
+
+/**
+ * __wake_up_sync_key - wake up threads blocked on a waitqueue.
+ * @q: the waitqueue
+ * @mode: which threads
+ * @nr_exclusive: how many wake-one or wake-many threads to wake up
+ * @key: opaque value to be passed to wakeup targets
+ *
+ * The sync wakeup differs that the waker knows that it will schedule
+ * away soon, so while the target thread will be woken up, it will not
+ * be migrated to another CPU - ie. the two threads are 'synchronised'
+ * with each other. This can prevent needless bouncing between CPUs.
+ *
+ * On UP it can prevent extra preemption.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
+ */
+void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
+ int nr_exclusive, void *key)
+{
+ unsigned long flags;
+ int wake_flags = WF_SYNC;
+
+ if (unlikely(!q))
+ return;
+
+ if (unlikely(!nr_exclusive))
+ wake_flags = 0;
+
+ spin_lock_irqsave(&q->lock, flags);
+ __wake_up_common(q, mode, nr_exclusive, wake_flags, key);
+ spin_unlock_irqrestore(&q->lock, flags);
+}
+EXPORT_SYMBOL_GPL(__wake_up_sync_key);
+
+/**
+ * __wake_up_sync - wake up threads blocked on a waitqueue.
+ * @q: the waitqueue
+ * @mode: which threads
+ * @nr_exclusive: how many wake-one or wake-many threads to wake up
+ *
+ * The sync wakeup differs that the waker knows that it will schedule
+ * away soon, so while the target thread will be woken up, it will not
+ * be migrated to another CPU - ie. the two threads are 'synchronised'
+ * with each other. This can prevent needless bouncing between CPUs.
+ *
+ * On UP it can prevent extra preemption.
+ */
+void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
+{
+ unsigned long flags;
+ int sync = 1;
+
+ if (unlikely(!q))
+ return;
+
+ if (unlikely(!nr_exclusive))
+ sync = 0;
+
+ spin_lock_irqsave(&q->lock, flags);
+ __wake_up_common(q, mode, nr_exclusive, sync, NULL);
+ spin_unlock_irqrestore(&q->lock, flags);
+}
+EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
+
+/**
+ * complete: - signals a single thread waiting on this completion
+ * @x: holds the state of this particular completion
+ *
+ * This will wake up a single thread waiting on this completion. Threads will be
+ * awakened in the same order in which they were queued.
+ *
+ * See also complete_all(), wait_for_completion() and related routines.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
+ */
+void complete(struct completion *x)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&x->wait.lock, flags);
+ x->done++;
+ __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
+ spin_unlock_irqrestore(&x->wait.lock, flags);
+}
+EXPORT_SYMBOL(complete);
+
+/**
+ * complete_all: - signals all threads waiting on this completion
+ * @x: holds the state of this particular completion
+ *
+ * This will wake up all threads waiting on this particular completion event.
+ *
+ * It may be assumed that this function implies a write memory barrier before
+ * changing the task state if and only if any tasks are woken up.
+ */
+void complete_all(struct completion *x)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&x->wait.lock, flags);
+ x->done += UINT_MAX/2;
+ __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
+ spin_unlock_irqrestore(&x->wait.lock, flags);
+}
+EXPORT_SYMBOL(complete_all);
+
+static inline long __sched
+do_wait_for_common(struct completion *x, long timeout, int state)
+{
+ if (!x->done) {
+ DECLARE_WAITQUEUE(wait, current);
+
+ wait.flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue_tail(&x->wait, &wait);
+ do {
+ if (signal_pending_state(state, current)) {
+ timeout = -ERESTARTSYS;
+ break;
+ }
+ __set_current_state(state);
+ spin_unlock_irq(&x->wait.lock);
+ timeout = schedule_timeout(timeout);
+ spin_lock_irq(&x->wait.lock);
+ } while (!x->done && timeout);
+ __remove_wait_queue(&x->wait, &wait);
+ if (!x->done)
+ return timeout;
+ }
+ x->done--;
+ return timeout ?: 1;
+}
+
+static long __sched
+wait_for_common(struct completion *x, long timeout, int state)
+{
+ might_sleep();
+
+ spin_lock_irq(&x->wait.lock);
+ timeout = do_wait_for_common(x, timeout, state);
+ spin_unlock_irq(&x->wait.lock);
+ return timeout;
+}
+
+/**
+ * wait_for_completion: - waits for completion of a task
+ * @x: holds the state of this particular completion
+ *
+ * This waits to be signaled for completion of a specific task. It is NOT
+ * interruptible and there is no timeout.
+ *
+ * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
+ * and interrupt capability. Also see complete().
+ */
+void __sched wait_for_completion(struct completion *x)
+{
+ wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
+}
+EXPORT_SYMBOL(wait_for_completion);
+
+/**
+ * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
+ * @x: holds the state of this particular completion
+ * @timeout: timeout value in jiffies
+ *
+ * This waits for either a completion of a specific task to be signaled or for a
+ * specified timeout to expire. The timeout is in jiffies. It is not
+ * interruptible.
+ */
+unsigned long __sched
+wait_for_completion_timeout(struct completion *x, unsigned long timeout)
+{
+ return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
+}
+EXPORT_SYMBOL(wait_for_completion_timeout);
+
+/**
+ * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
+ * @x: holds the state of this particular completion
+ *
+ * This waits for completion of a specific task to be signaled. It is
+ * interruptible.
+ */
+int __sched wait_for_completion_interruptible(struct completion *x)
+{
+ long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
+ if (t == -ERESTARTSYS)
+ return t;
+ return 0;
+}
+EXPORT_SYMBOL(wait_for_completion_interruptible);
+
+/**
+ * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
+ * @x: holds the state of this particular completion
+ * @timeout: timeout value in jiffies
+ *
+ * This waits for either a completion of a specific task to be signaled or for a
+ * specified timeout to expire. It is interruptible. The timeout is in jiffies.
+ */
+unsigned long __sched
+wait_for_completion_interruptible_timeout(struct completion *x,
+ unsigned long timeout)
+{
+ return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
+}
+EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
+
+/**
+ * wait_for_completion_killable: - waits for completion of a task (killable)
+ * @x: holds the state of this particular completion
+ *
+ * This waits to be signaled for completion of a specific task. It can be
+ * interrupted by a kill signal.
+ */
+int __sched wait_for_completion_killable(struct completion *x)
+{
+ long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
+ if (t == -ERESTARTSYS)
+ return t;
+ return 0;
+}
+EXPORT_SYMBOL(wait_for_completion_killable);
+
+/**
+ * try_wait_for_completion - try to decrement a completion without blocking
+ * @x: completion structure
+ *
+ * Returns: 0 if a decrement cannot be done without blocking
+ * 1 if a decrement succeeded.
+ *
+ * If a completion is being used as a counting completion,
+ * attempt to decrement the counter without blocking. This
+ * enables us to avoid waiting if the resource the completion
+ * is protecting is not available.
+ */
+bool try_wait_for_completion(struct completion *x)
+{
+ int ret = 1;
+
+ spin_lock_irq(&x->wait.lock);
+ if (!x->done)
+ ret = 0;
+ else
+ x->done--;
+ spin_unlock_irq(&x->wait.lock);
+ return ret;
+}
+EXPORT_SYMBOL(try_wait_for_completion);
+
+/**
+ * completion_done - Test to see if a completion has any waiters
+ * @x: completion structure
+ *
+ * Returns: 0 if there are waiters (wait_for_completion() in progress)
+ * 1 if there are no waiters.
+ *
+ */
+bool completion_done(struct completion *x)
+{
+ int ret = 1;
+
+ spin_lock_irq(&x->wait.lock);
+ if (!x->done)
+ ret = 0;
+ spin_unlock_irq(&x->wait.lock);
+ return ret;
+}
+EXPORT_SYMBOL(completion_done);
+
+static long __sched
+sleep_on_common(wait_queue_head_t *q, int state, long timeout)
+{
+ unsigned long flags;
+ wait_queue_t wait;
+
+ init_waitqueue_entry(&wait, current);
+
+ __set_current_state(state);
+
+ spin_lock_irqsave(&q->lock, flags);
+ __add_wait_queue(q, &wait);
+ spin_unlock(&q->lock);
+ timeout = schedule_timeout(timeout);
+ spin_lock_irq(&q->lock);
+ __remove_wait_queue(q, &wait);
+ spin_unlock_irqrestore(&q->lock, flags);
+
+ return timeout;
+}
+
+void __sched interruptible_sleep_on(wait_queue_head_t *q)
+{
+ sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+EXPORT_SYMBOL(interruptible_sleep_on);
+
+long __sched
+interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
+{
+ return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
+}
+EXPORT_SYMBOL(interruptible_sleep_on_timeout);
+
+void __sched sleep_on(wait_queue_head_t *q)
+{
+ sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+EXPORT_SYMBOL(sleep_on);
+
+long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
+{
+ return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
+}
+EXPORT_SYMBOL(sleep_on_timeout);
+
+#ifdef CONFIG_RT_MUTEXES
+
+/*
+ * rt_mutex_setprio - set the current priority of a task
+ * @p: task
+ * @prio: prio value (kernel-internal form)
+ *
+ * This function changes the 'effective' priority of a task. It does
+ * not touch ->normal_prio like __setscheduler().
+ *
+ * Used by the rt_mutex code to implement priority inheritance logic.
+ */
+void rt_mutex_setprio(struct task_struct *p, int prio)
+{
+ unsigned long flags;
+ int queued, oldprio;
+ struct rq *rq;
+
+ BUG_ON(prio < 0 || prio > MAX_PRIO);
+
+ rq = time_task_grq_lock(p, &flags);
+
+ oldprio = p->prio;
+ queued = task_queued(p);
+ if (queued)
+ dequeue_task(p);
+ p->prio = prio;
+ if (task_running(p) && prio > oldprio)
+ resched_task(p);
+ if (queued) {
+ enqueue_task(p);
+ try_preempt(p, rq);
+ }
+
+ task_grq_unlock(&flags);
+}
+
+#endif
+
+/*
+ * Adjust the deadline for when the priority is to change, before it's
+ * changed.
+ */
+static inline void adjust_deadline(struct task_struct *p, int new_prio)
+{
+ p->deadline += static_deadline_diff(new_prio) - task_deadline_diff(p);
+}
+
+void set_user_nice(struct task_struct *p, long nice)
+{
+ int queued, new_static, old_static;
+ unsigned long flags;
+ struct rq *rq;
+
+ if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
+ return;
+ new_static = NICE_TO_PRIO(nice);
+ /*
+ * We have to be careful, if called from sys_setpriority(),
+ * the task might be in the middle of scheduling on another CPU.
+ */
+ rq = time_task_grq_lock(p, &flags);
+ /*
+ * The RT priorities are set via sched_setscheduler(), but we still
+ * allow the 'normal' nice value to be set - but as expected
+ * it wont have any effect on scheduling until the task is
+ * not SCHED_NORMAL/SCHED_BATCH:
+ */
+ if (has_rt_policy(p)) {
+ p->static_prio = new_static;
+ goto out_unlock;
+ }
+ queued = task_queued(p);
+ if (queued)
+ dequeue_task(p);
+
+ adjust_deadline(p, new_static);
+ old_static = p->static_prio;
+ p->static_prio = new_static;
+ p->prio = effective_prio(p);
+
+ if (queued) {
+ enqueue_task(p);
+ if (new_static < old_static)
+ try_preempt(p, rq);
+ } else if (task_running(p)) {
+ reset_rq_task(rq, p);
+ if (old_static < new_static)
+ resched_task(p);
+ }
+out_unlock:
+ task_grq_unlock(&flags);
+}
+EXPORT_SYMBOL(set_user_nice);
+
+/*
+ * can_nice - check if a task can reduce its nice value
+ * @p: task
+ * @nice: nice value
+ */
+int can_nice(const struct task_struct *p, const int nice)
+{
+ /* convert nice value [19,-20] to rlimit style value [1,40] */
+ int nice_rlim = 20 - nice;
+
+ return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
+ capable(CAP_SYS_NICE));
+}
+
+#ifdef __ARCH_WANT_SYS_NICE
+
+/*
+ * sys_nice - change the priority of the current process.
+ * @increment: priority increment
+ *
+ * sys_setpriority is a more generic, but much slower function that
+ * does similar things.
+ */
+SYSCALL_DEFINE1(nice, int, increment)
+{
+ long nice, retval;
+
+ /*
+ * Setpriority might change our priority at the same moment.
+ * We don't have to worry. Conceptually one call occurs first
+ * and we have a single winner.
+ */
+ if (increment < -40)
+ increment = -40;
+ if (increment > 40)
+ increment = 40;
+
+ nice = TASK_NICE(current) + increment;
+ if (nice < -20)
+ nice = -20;
+ if (nice > 19)
+ nice = 19;
+
+ if (increment < 0 && !can_nice(current, nice))
+ return -EPERM;
+
+ retval = security_task_setnice(current, nice);
+ if (retval)
+ return retval;
+
+ set_user_nice(current, nice);
+ return 0;
+}
+
+#endif
+
+/**
+ * task_prio - return the priority value of a given task.
+ * @p: the task in question.
+ *
+ * This is the priority value as seen by users in /proc.
+ * RT tasks are offset by -100. Normal tasks are centered around 1, value goes
+ * from 0 (SCHED_ISO) up to 82 (nice +19 SCHED_IDLEPRIO).
+ */
+int task_prio(const struct task_struct *p)
+{
+ int delta, prio = p->prio - MAX_RT_PRIO;
+
+ /* rt tasks and iso tasks */
+ if (prio <= 0)
+ goto out;
+
+ delta = (p->deadline - jiffies) * 40 / longest_deadline_diff();
+ if (delta > 0 && delta <= 80)
+ prio += delta;
+ if (idleprio_task(p))
+ prio += 40;
+out:
+ return prio;
+}
+
+/**
+ * task_nice - return the nice value of a given task.
+ * @p: the task in question.
+ */
+int task_nice(const struct task_struct *p)
+{
+ return TASK_NICE(p);
+}
+EXPORT_SYMBOL_GPL(task_nice);
+
+/**
+ * idle_cpu - is a given cpu idle currently?
+ * @cpu: the processor in question.
+ */
+int idle_cpu(int cpu)
+{
+ return cpu_curr(cpu) == cpu_rq(cpu)->idle;
+}
+
+/**
+ * idle_task - return the idle task for a given cpu.
+ * @cpu: the processor in question.
+ */
+struct task_struct *idle_task(int cpu)
+{
+ return cpu_rq(cpu)->idle;
+}
+
+/**
+ * find_process_by_pid - find a process with a matching PID value.
+ * @pid: the pid in question.
+ */
+static inline struct task_struct *find_process_by_pid(pid_t pid)
+{
+ return pid ? find_task_by_vpid(pid) : current;
+}
+
+/* Actually do priority change: must hold grq lock. */
+static void
+__setscheduler(struct task_struct *p, struct rq *rq, int policy, int prio)
+{
+ int oldrtprio, oldprio;
+
+ BUG_ON(task_queued(p));
+
+ p->policy = policy;
+ oldrtprio = p->rt_priority;
+ p->rt_priority = prio;
+ p->normal_prio = normal_prio(p);
+ oldprio = p->prio;
+ /* we are holding p->pi_lock already */
+ p->prio = rt_mutex_getprio(p);
+ if (task_running(p)) {
+ reset_rq_task(rq, p);
+ /* Resched only if we might now be preempted */
+ if (p->prio > oldprio || p->rt_priority > oldrtprio)
+ resched_task(p);
+ }
+}
+
+/*
+ * check the target process has a UID that matches the current process's
+ */
+static bool check_same_owner(struct task_struct *p)
+{
+ const struct cred *cred = current_cred(), *pcred;
+ bool match;
+
+ rcu_read_lock();
+ pcred = __task_cred(p);
+ match = (cred->euid == pcred->euid ||
+ cred->euid == pcred->uid);
+ rcu_read_unlock();
+ return match;
+}
+
+static int __sched_setscheduler(struct task_struct *p, int policy,
+ struct sched_param *param, bool user)
+{
+ struct sched_param zero_param = { .sched_priority = 0 };
+ int queued, retval, oldpolicy = -1;
+ unsigned long flags, rlim_rtprio = 0;
+ int reset_on_fork;
+ struct rq *rq;
+
+ /* may grab non-irq protected spin_locks */
+ BUG_ON(in_interrupt());
+
+ if (is_rt_policy(policy) && !capable(CAP_SYS_NICE)) {
+ unsigned long lflags;
+
+ if (!lock_task_sighand(p, &lflags))
+ return -ESRCH;
+ rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
+ unlock_task_sighand(p, &lflags);
+ if (rlim_rtprio)
+ goto recheck;
+ /*
+ * If the caller requested an RT policy without having the
+ * necessary rights, we downgrade the policy to SCHED_ISO.
+ * We also set the parameter to zero to pass the checks.
+ */
+ policy = SCHED_ISO;
+ param = &zero_param;
+ }
+recheck:
+ /* double check policy once rq lock held */
+ if (policy < 0) {
+ reset_on_fork = p->sched_reset_on_fork;
+ policy = oldpolicy = p->policy;
+ } else {
+ reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
+ policy &= ~SCHED_RESET_ON_FORK;
+
+ if (!SCHED_RANGE(policy))
+ return -EINVAL;
+ }
+
+ /*
+ * Valid priorities for SCHED_FIFO and SCHED_RR are
+ * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
+ * SCHED_BATCH is 0.
+ */
+ if (param->sched_priority < 0 ||
+ (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
+ (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
+ return -EINVAL;
+ if (is_rt_policy(policy) != (param->sched_priority != 0))
+ return -EINVAL;
+
+ /*
+ * Allow unprivileged RT tasks to decrease priority:
+ */
+ if (user && !capable(CAP_SYS_NICE)) {
+ if (is_rt_policy(policy)) {
+ /* can't set/change the rt policy */
+ if (policy != p->policy && !rlim_rtprio)
+ return -EPERM;
+
+ /* can't increase priority */
+ if (param->sched_priority > p->rt_priority &&
+ param->sched_priority > rlim_rtprio)
+ return -EPERM;
+ } else {
+ switch (p->policy) {
+ /*
+ * Can only downgrade policies but not back to
+ * SCHED_NORMAL
+ */
+ case SCHED_ISO:
+ if (policy == SCHED_ISO)
+ goto out;
+ if (policy == SCHED_NORMAL)
+ return -EPERM;
+ break;
+ case SCHED_BATCH:
+ if (policy == SCHED_BATCH)
+ goto out;
+ if (policy != SCHED_IDLEPRIO)
+ return -EPERM;
+ break;
+ case SCHED_IDLEPRIO:
+ if (policy == SCHED_IDLEPRIO)
+ goto out;
+ return -EPERM;
+ default:
+ break;
+ }
+ }
+
+ /* can't change other user's priorities */
+ if (!check_same_owner(p))
+ return -EPERM;
+
+ /* Normal users shall not reset the sched_reset_on_fork flag */
+ if (p->sched_reset_on_fork && !reset_on_fork)
+ return -EPERM;
+ }
+
+ retval = security_task_setscheduler(p, policy, param);
+ if (retval)
+ return retval;
+ /*
+ * make sure no PI-waiters arrive (or leave) while we are
+ * changing the priority of the task:
+ */
+ spin_lock_irqsave(&p->pi_lock, flags);
+ /*
+ * To be able to change p->policy safely, the apropriate
+ * runqueue lock must be held.
+ */
+ rq = __task_grq_lock(p);
+ /* recheck policy now with rq lock held */
+ if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
+ __task_grq_unlock();
+ spin_unlock_irqrestore(&p->pi_lock, flags);
+ policy = oldpolicy = -1;
+ goto recheck;
+ }
+ update_rq_clock(rq);
+ p->sched_reset_on_fork = reset_on_fork;
+
+ queued = task_queued(p);
+ if (queued)
+ dequeue_task(p);
+ __setscheduler(p, rq, policy, param->sched_priority);
+ if (queued) {
+ enqueue_task(p);
+ try_preempt(p, rq);
+ }
+ __task_grq_unlock();
+ spin_unlock_irqrestore(&p->pi_lock, flags);
+
+ rt_mutex_adjust_pi(p);
+out:
+ return 0;
+}
+
+/**
+ * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
+ * @p: the task in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ *
+ * NOTE that the task may be already dead.
+ */
+int sched_setscheduler(struct task_struct *p, int policy,
+ struct sched_param *param)
+{
+ return __sched_setscheduler(p, policy, param, true);
+}
+
+EXPORT_SYMBOL_GPL(sched_setscheduler);
+
+/**
+ * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
+ * @p: the task in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ *
+ * Just like sched_setscheduler, only don't bother checking if the
+ * current context has permission. For example, this is needed in
+ * stop_machine(): we create temporary high priority worker threads,
+ * but our caller might not have that capability.
+ */
+int sched_setscheduler_nocheck(struct task_struct *p, int policy,
+ struct sched_param *param)
+{
+ return __sched_setscheduler(p, policy, param, false);
+}
+
+static int
+do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
+{
+ struct sched_param lparam;
+ struct task_struct *p;
+ int retval;
+
+ if (!param || pid < 0)
+ return -EINVAL;
+ if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
+ return -EFAULT;
+
+ rcu_read_lock();
+ retval = -ESRCH;
+ p = find_process_by_pid(pid);
+ if (p != NULL)
+ retval = sched_setscheduler(p, policy, &lparam);
+ rcu_read_unlock();
+
+ return retval;
+}
+
+/**
+ * sys_sched_setscheduler - set/change the scheduler policy and RT priority
+ * @pid: the pid in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ */
+asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
+ struct sched_param __user *param)
+{
+ /* negative values for policy are not valid */
+ if (policy < 0)
+ return -EINVAL;
+
+ return do_sched_setscheduler(pid, policy, param);
+}
+
+/**
+ * sys_sched_setparam - set/change the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the new RT priority.
+ */
+SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
+{
+ return do_sched_setscheduler(pid, -1, param);
+}
+
+/**
+ * sys_sched_getscheduler - get the policy (scheduling class) of a thread
+ * @pid: the pid in question.
+ */
+SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
+{
+ struct task_struct *p;
+ int retval = -EINVAL;
+
+ if (pid < 0)
+ goto out_nounlock;
+
+ retval = -ESRCH;
+ read_lock(&tasklist_lock);
+ p = find_process_by_pid(pid);
+ if (p) {
+ retval = security_task_getscheduler(p);
+ if (!retval)
+ retval = p->policy;
+ }
+ read_unlock(&tasklist_lock);
+
+out_nounlock:
+ return retval;
+}
+
+/**
+ * sys_sched_getscheduler - get the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the RT priority.
+ */
+SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
+{
+ struct sched_param lp;
+ struct task_struct *p;
+ int retval = -EINVAL;
+
+ if (!param || pid < 0)
+ goto out_nounlock;
+
+ read_lock(&tasklist_lock);
+ p = find_process_by_pid(pid);
+ retval = -ESRCH;
+ if (!p)
+ goto out_unlock;
+
+ retval = security_task_getscheduler(p);
+ if (retval)
+ goto out_unlock;
+
+ lp.sched_priority = p->rt_priority;
+ read_unlock(&tasklist_lock);
+
+ /*
+ * This one might sleep, we cannot do it with a spinlock held ...
+ */
+ retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
+
+out_nounlock:
+ return retval;
+
+out_unlock:
+ read_unlock(&tasklist_lock);
+ return retval;
+}
+
+long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+{
+ cpumask_var_t cpus_allowed, new_mask;
+ struct task_struct *p;
+ int retval;
+
+ get_online_cpus();
+ read_lock(&tasklist_lock);
+
+ p = find_process_by_pid(pid);
+ if (!p) {
+ read_unlock(&tasklist_lock);
+ put_online_cpus();
+ return -ESRCH;
+ }
+
+ /*
+ * It is not safe to call set_cpus_allowed with the
+ * tasklist_lock held. We will bump the task_struct's
+ * usage count and then drop tasklist_lock.
+ */
+ get_task_struct(p);
+ read_unlock(&tasklist_lock);
+
+ if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
+ retval = -ENOMEM;
+ goto out_put_task;
+ }
+ if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
+ retval = -ENOMEM;
+ goto out_free_cpus_allowed;
+ }
+ retval = -EPERM;
+ if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
+ goto out_unlock;
+
+ retval = security_task_setscheduler(p, 0, NULL);
+ if (retval)
+ goto out_unlock;
+
+ cpuset_cpus_allowed(p, cpus_allowed);
+ cpumask_and(new_mask, in_mask, cpus_allowed);
+again:
+ retval = set_cpus_allowed_ptr(p, new_mask);
+
+ if (!retval) {
+ cpuset_cpus_allowed(p, cpus_allowed);
+ if (!cpumask_subset(new_mask, cpus_allowed)) {
+ /*
+ * We must have raced with a concurrent cpuset
+ * update. Just reset the cpus_allowed to the
+ * cpuset's cpus_allowed
+ */
+ cpumask_copy(new_mask, cpus_allowed);
+ goto again;
+ }
+ }
+out_unlock:
+ free_cpumask_var(new_mask);
+out_free_cpus_allowed:
+ free_cpumask_var(cpus_allowed);
+out_put_task:
+ put_task_struct(p);
+ put_online_cpus();
+ return retval;
+}
+
+static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
+ cpumask_t *new_mask)
+{
+ if (len < sizeof(cpumask_t)) {
+ memset(new_mask, 0, sizeof(cpumask_t));
+ } else if (len > sizeof(cpumask_t)) {
+ len = sizeof(cpumask_t);
+ }
+ return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
+}
+
+
+/**
+ * sys_sched_setaffinity - set the cpu affinity of a process
+ * @pid: pid of the process
+ * @len: length in bytes of the bitmask pointed to by user_mask_ptr
+ * @user_mask_ptr: user-space pointer to the new cpu mask
+ */
+SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
+ unsigned long __user *, user_mask_ptr)
+{
+ cpumask_var_t new_mask;
+ int retval;
+
+ if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
+ return -ENOMEM;
+
+ retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
+ if (retval == 0)
+ retval = sched_setaffinity(pid, new_mask);
+ free_cpumask_var(new_mask);
+ return retval;
+}
+
+long sched_getaffinity(pid_t pid, cpumask_t *mask)
+{
+ struct task_struct *p;
+ int retval;
+
+ mutex_lock(&sched_hotcpu_mutex);
+ read_lock(&tasklist_lock);
+
+ retval = -ESRCH;
+ p = find_process_by_pid(pid);
+ if (!p)
+ goto out_unlock;
+
+ retval = security_task_getscheduler(p);
+ if (retval)
+ goto out_unlock;
+
+ cpus_and(*mask, p->cpus_allowed, cpu_online_map);
+
+out_unlock:
+ read_unlock(&tasklist_lock);
+ mutex_unlock(&sched_hotcpu_mutex);
+ if (retval)
+ return retval;
+
+ return 0;
+}
+
+/**
+ * sys_sched_getaffinity - get the cpu affinity of a process
+ * @pid: pid of the process
+ * @len: length in bytes of the bitmask pointed to by user_mask_ptr
+ * @user_mask_ptr: user-space pointer to hold the current cpu mask
+ */
+SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
+ unsigned long __user *, user_mask_ptr)
+{
+ int ret;
+ cpumask_var_t mask;
+
+ if (len < cpumask_size())
+ return -EINVAL;
+
+ if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+ return -ENOMEM;
+
+ ret = sched_getaffinity(pid, mask);
+ if (ret == 0) {
+ if (copy_to_user(user_mask_ptr, mask, cpumask_size()))
+ ret = -EFAULT;
+ else
+ ret = cpumask_size();
+ }
+ free_cpumask_var(mask);
+
+ return ret;
+}
+
+/**
+ * sys_sched_yield - yield the current processor to other threads.
+ *
+ * This function yields the current CPU to other tasks. It does this by
+ * scheduling away the current task. If it still has the earliest deadline
+ * it will be scheduled again as the next task.
+ */
+SYSCALL_DEFINE0(sched_yield)
+{
+ struct task_struct *p;
+ struct rq *rq;
+
+ p = current;
+ rq = task_grq_lock_irq(p);
+ schedstat_inc(rq, yld_count);
+ requeue_task(p);
+
+ /*
+ * Since we are going to call schedule() anyway, there's
+ * no need to preempt or enable interrupts:
+ */
+ __release(grq.lock);
+ spin_release(&grq.lock.dep_map, 1, _THIS_IP_);
+ _raw_spin_unlock(&grq.lock);
+ preempt_enable_no_resched();
+
+ schedule();
+
+ return 0;
+}
+
+static inline int should_resched(void)
+{
+ return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
+}
+
+static void __cond_resched(void)
+{
+ /* NOT a real fix but will make voluntary preempt work. 馬鹿なäº. */
+ if (unlikely(system_state != SYSTEM_RUNNING))
+ return;
+
+ add_preempt_count(PREEMPT_ACTIVE);
+ schedule();
+ sub_preempt_count(PREEMPT_ACTIVE);
+}
+
+int __sched _cond_resched(void)
+{
+ if (should_resched()) {
+ __cond_resched();
+ return 1;
+ }
+ return 0;
+}
+EXPORT_SYMBOL(_cond_resched);
+
+/*
+ * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
+ * call schedule, and on return reacquire the lock.
+ *
+ * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
+ * operations here to prevent schedule() from being called twice (once via
+ * spin_unlock(), once by hand).
+ */
+int __cond_resched_lock(spinlock_t *lock)
+{
+ int resched = should_resched();
+ int ret = 0;
+
+ lockdep_assert_held(lock);
+
+ if (spin_needbreak(lock) || resched) {
+ spin_unlock(lock);
+ if (resched)
+ __cond_resched();
+ else
+ cpu_relax();
+ ret = 1;
+ spin_lock(lock);
+ }
+ return ret;
+}
+EXPORT_SYMBOL(__cond_resched_lock);
+
+int __sched __cond_resched_softirq(void)
+{
+ BUG_ON(!in_softirq());
+
+ if (should_resched()) {
+ local_bh_enable();
+ __cond_resched();
+ local_bh_disable();
+ return 1;
+ }
+ return 0;
+}
+EXPORT_SYMBOL(__cond_resched_softirq);
+
+/**
+ * yield - yield the current processor to other threads.
+ *
+ * This is a shortcut for kernel-space yielding - it marks the
+ * thread runnable and calls sys_sched_yield().
+ */
+void __sched yield(void)
+{
+ set_current_state(TASK_RUNNING);
+ sys_sched_yield();
+}
+EXPORT_SYMBOL(yield);
+
+/*
+ * This task is about to go to sleep on IO. Increment rq->nr_iowait so
+ * that process accounting knows that this is a task in IO wait state.
+ *
+ * But don't do that if it is a deliberate, throttling IO wait (this task
+ * has set its backing_dev_info: the queue against which it should throttle)
+ */
+void __sched io_schedule(void)
+{
+ struct rq *rq = raw_rq();
+
+ delayacct_blkio_start();
+ atomic_inc(&rq->nr_iowait);
+ current->in_iowait = 1;
+ schedule();
+ current->in_iowait = 0;
+ atomic_dec(&rq->nr_iowait);
+ delayacct_blkio_end();
+}
+EXPORT_SYMBOL(io_schedule);
+
+long __sched io_schedule_timeout(long timeout)
+{
+ struct rq *rq = raw_rq();
+ long ret;
+
+ delayacct_blkio_start();
+ atomic_inc(&rq->nr_iowait);
+ current->in_iowait = 1;
+ ret = schedule_timeout(timeout);
+ current->in_iowait = 0;
+ atomic_dec(&rq->nr_iowait);
+ delayacct_blkio_end();
+ return ret;
+}
+
+/**
+ * sys_sched_get_priority_max - return maximum RT priority.
+ * @policy: scheduling class.
+ *
+ * this syscall returns the maximum rt_priority that can be used
+ * by a given scheduling class.
+ */
+SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
+{
+ int ret = -EINVAL;
+
+ switch (policy) {
+ case SCHED_FIFO:
+ case SCHED_RR:
+ ret = MAX_USER_RT_PRIO-1;
+ break;
+ case SCHED_NORMAL:
+ case SCHED_BATCH:
+ case SCHED_ISO:
+ case SCHED_IDLEPRIO:
+ ret = 0;
+ break;
+ }
+ return ret;
+}
+
+/**
+ * sys_sched_get_priority_min - return minimum RT priority.
+ * @policy: scheduling class.
+ *
+ * this syscall returns the minimum rt_priority that can be used
+ * by a given scheduling class.
+ */
+SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
+{
+ int ret = -EINVAL;
+
+ switch (policy) {
+ case SCHED_FIFO:
+ case SCHED_RR:
+ ret = 1;
+ break;
+ case SCHED_NORMAL:
+ case SCHED_BATCH:
+ case SCHED_ISO:
+ case SCHED_IDLEPRIO:
+ ret = 0;
+ break;
+ }
+ return ret;
+}
+
+/**
+ * sys_sched_rr_get_interval - return the default timeslice of a process.
+ * @pid: pid of the process.
+ * @interval: userspace pointer to the timeslice value.
+ *
+ * this syscall writes the default timeslice value of a given process
+ * into the user-space timespec buffer. A value of '0' means infinity.
+ */
+SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
+ struct timespec __user *, interval)
+{
+ struct task_struct *p;
+ int retval = -EINVAL;
+ struct timespec t;
+
+ if (pid < 0)
+ goto out_nounlock;
+
+ retval = -ESRCH;
+ read_lock(&tasklist_lock);
+ p = find_process_by_pid(pid);
+ if (!p)
+ goto out_unlock;
+
+ retval = security_task_getscheduler(p);
+ if (retval)
+ goto out_unlock;
+
+ t = ns_to_timespec(p->policy == SCHED_FIFO ? 0 :
+ MS_TO_NS(task_timeslice(p)));
+ read_unlock(&tasklist_lock);
+ retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
+out_nounlock:
+ return retval;
+out_unlock:
+ read_unlock(&tasklist_lock);
+ return retval;
+}
+
+static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
+
+void sched_show_task(struct task_struct *p)
+{
+ unsigned long free = 0;
+ unsigned state;
+
+ state = p->state ? __ffs(p->state) + 1 : 0;
+ printk(KERN_INFO "%-13.13s %c", p->comm,
+ state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
+#if BITS_PER_LONG == 32
+ if (state == TASK_RUNNING)
+ printk(KERN_CONT " running ");
+ else
+ printk(KERN_CONT " %08lx ", thread_saved_pc(p));
+#else
+ if (state == TASK_RUNNING)
+ printk(KERN_CONT " running task ");
+ else
+ printk(KERN_CONT " %016lx ", thread_saved_pc(p));
+#endif
+#ifdef CONFIG_DEBUG_STACK_USAGE
+ free = stack_not_used(p);
+#endif
+ printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
+ task_pid_nr(p), task_pid_nr(p->real_parent),
+ (unsigned long)task_thread_info(p)->flags);
+
+ show_stack(p, NULL);
+}
+
+void show_state_filter(unsigned long state_filter)
+{
+ struct task_struct *g, *p;
+
+#if BITS_PER_LONG == 32
+ printk(KERN_INFO
+ " task PC stack pid father\n");
+#else
+ printk(KERN_INFO
+ " task PC stack pid father\n");
+#endif
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ /*
+ * reset the NMI-timeout, listing all files on a slow
+ * console might take alot of time:
+ */
+ touch_nmi_watchdog();
+ if (!state_filter || (p->state & state_filter))
+ sched_show_task(p);
+ } while_each_thread(g, p);
+
+ touch_all_softlockup_watchdogs();
+
+ read_unlock(&tasklist_lock);
+ /*
+ * Only show locks if all tasks are dumped:
+ */
+ if (state_filter == -1)
+ debug_show_all_locks();
+}
+
+/**
+ * init_idle - set up an idle thread for a given CPU
+ * @idle: task in question
+ * @cpu: cpu the idle task belongs to
+ *
+ * NOTE: this function does not set the idle thread's NEED_RESCHED
+ * flag, to make booting more robust.
+ */
+void init_idle(struct task_struct *idle, int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long flags;
+
+ time_grq_lock(rq, &flags);
+ idle->last_ran = rq->clock;
+ idle->state = TASK_RUNNING;
+ /* Setting prio to illegal value shouldn't matter when never queued */
+ idle->prio = PRIO_LIMIT;
+ set_rq_task(rq, idle);
+ idle->cpus_allowed = cpumask_of_cpu(cpu);
+ set_task_cpu(idle, cpu);
+ rq->curr = rq->idle = idle;
+ idle->oncpu = 1;
+ set_cpuidle_map(cpu);
+#ifdef CONFIG_HOTPLUG_CPU
+ idle->unplugged_mask = CPU_MASK_NONE;
+#endif
+ grq_unlock_irqrestore(&flags);
+
+ /* Set the preempt count _outside_ the spinlocks! */
+#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
+ task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
+#else
+ task_thread_info(idle)->preempt_count = 0;
+#endif
+ ftrace_graph_init_task(idle);
+}
+
+/*
+ * In a system that switches off the HZ timer nohz_cpu_mask
+ * indicates which cpus entered this state. This is used
+ * in the rcu update to wait only for active cpus. For system
+ * which do not switch off the HZ timer nohz_cpu_mask should
+ * always be CPU_BITS_NONE.
+ */
+cpumask_var_t nohz_cpu_mask;
+
+#ifdef CONFIG_SMP
+#ifdef CONFIG_NO_HZ
+static struct {
+ atomic_t load_balancer;
+ cpumask_var_t cpu_mask;
+ cpumask_var_t ilb_grp_nohz_mask;
+} nohz ____cacheline_aligned = {
+ .load_balancer = ATOMIC_INIT(-1),
+};
+
+int get_nohz_load_balancer(void)
+{
+ return atomic_read(&nohz.load_balancer);
+}
+
+/*
+ * This routine will try to nominate the ilb (idle load balancing)
+ * owner among the cpus whose ticks are stopped. ilb owner will do the idle
+ * load balancing on behalf of all those cpus. If all the cpus in the system
+ * go into this tickless mode, then there will be no ilb owner (as there is
+ * no need for one) and all the cpus will sleep till the next wakeup event
+ * arrives...
+ *
+ * For the ilb owner, tick is not stopped. And this tick will be used
+ * for idle load balancing. ilb owner will still be part of
+ * nohz.cpu_mask..
+ *
+ * While stopping the tick, this cpu will become the ilb owner if there
+ * is no other owner. And will be the owner till that cpu becomes busy
+ * or if all cpus in the system stop their ticks at which point
+ * there is no need for ilb owner.
+ *
+ * When the ilb owner becomes busy, it nominates another owner, during the
+ * next busy scheduler_tick()
+ */
+int select_nohz_load_balancer(int stop_tick)
+{
+ int cpu = smp_processor_id();
+
+ if (stop_tick) {
+ cpu_rq(cpu)->in_nohz_recently = 1;
+
+ if (!cpu_active(cpu)) {
+ if (atomic_read(&nohz.load_balancer) != cpu)
+ return 0;
+
+ /*
+ * If we are going offline and still the leader,
+ * give up!
+ */
+ if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
+ BUG();
+
+ return 0;
+ }
+
+ cpumask_set_cpu(cpu, nohz.cpu_mask);
+
+ /* time for ilb owner also to sleep */
+ if (cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
+ if (atomic_read(&nohz.load_balancer) == cpu)
+ atomic_set(&nohz.load_balancer, -1);
+ return 0;
+ }
+
+ if (atomic_read(&nohz.load_balancer) == -1) {
+ /* make me the ilb owner */
+ if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
+ return 1;
+ } else if (atomic_read(&nohz.load_balancer) == cpu)
+ return 1;
+ } else {
+ if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
+ return 0;
+
+ cpumask_clear_cpu(cpu, nohz.cpu_mask);
+
+ if (atomic_read(&nohz.load_balancer) == cpu)
+ if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
+ BUG();
+ }
+ return 0;
+}
+
+/*
+ * When add_timer_on() enqueues a timer into the timer wheel of an
+ * idle CPU then this timer might expire before the next timer event
+ * which is scheduled to wake up that CPU. In case of a completely
+ * idle system the next event might even be infinite time into the
+ * future. wake_up_idle_cpu() ensures that the CPU is woken up and
+ * leaves the inner idle loop so the newly added timer is taken into
+ * account when the CPU goes back to idle and evaluates the timer
+ * wheel for the next timer event.
+ */
+void wake_up_idle_cpu(int cpu)
+{
+ struct task_struct *idle;
+ struct rq *rq;
+
+ if (cpu == smp_processor_id())
+ return;
+
+ rq = cpu_rq(cpu);
+ idle = rq->idle;
+
+ /*
+ * This is safe, as this function is called with the timer
+ * wheel base lock of (cpu) held. When the CPU is on the way
+ * to idle and has not yet set rq->curr to idle then it will
+ * be serialised on the timer wheel base lock and take the new
+ * timer into account automatically.
+ */
+ if (unlikely(rq->curr != idle))
+ return;
+
+ /*
+ * We can set TIF_RESCHED on the idle task of the other CPU
+ * lockless. The worst case is that the other CPU runs the
+ * idle task through an additional NOOP schedule()
+ */
+ set_tsk_need_resched(idle);
+
+ /* NEED_RESCHED must be visible before we test polling */
+ smp_mb();
+ if (!tsk_is_polling(idle))
+ smp_send_reschedule(cpu);
+}
+
+#endif /* CONFIG_NO_HZ */
+
+/*
+ * Change a given task's CPU affinity. Migrate the thread to a
+ * proper CPU and schedule it away if the CPU it's executing on
+ * is removed from the allowed bitmask.
+ *
+ * NOTE: the caller must have a valid reference to the task, the
+ * task must not exit() & deallocate itself prematurely. The
+ * call is not atomic; no spinlocks may be held.
+ */
+int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
+{
+ unsigned long flags;
+ int running_wrong = 0;
+ int queued = 0;
+ struct rq *rq;
+ int ret = 0;
+
+ rq = task_grq_lock(p, &flags);
+ if (!cpumask_intersects(new_mask, cpu_online_mask)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (unlikely((p->flags & PF_THREAD_BOUND) && p != current &&
+ !cpumask_equal(&p->cpus_allowed, new_mask))) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ queued = task_queued(p);
+
+ cpumask_copy(&p->cpus_allowed, new_mask);
+
+ /* Can the task run on the task's current CPU? If so, we're done */
+ if (cpumask_test_cpu(task_cpu(p), new_mask))
+ goto out;
+
+ if (task_running(p)) {
+ /* Task is running on the wrong cpu now, reschedule it. */
+ set_tsk_need_resched(p);
+ running_wrong = 1;
+ } else {
+ get_cpu();
+ set_task_cpu(p, cpumask_any_and(cpu_active_mask, new_mask));
+ put_cpu();
+ }
+
+out:
+ if (queued)
+ try_preempt(p, rq);
+ task_grq_unlock(&flags);
+
+ if (running_wrong)
+ _cond_resched();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
+
+#ifdef CONFIG_HOTPLUG_CPU
+/* Schedules idle task to be the next runnable task on current CPU.
+ * It does so by boosting its priority to highest possible.
+ * Used by CPU offline code.
+ */
+void sched_idle_next(void)
+{
+ int this_cpu = smp_processor_id();
+ struct rq *rq = cpu_rq(this_cpu);
+ struct task_struct *idle = rq->idle;
+ unsigned long flags;
+
+ /* cpu has to be offline */
+ BUG_ON(cpu_online(this_cpu));
+
+ /*
+ * Strictly not necessary since rest of the CPUs are stopped by now
+ * and interrupts disabled on the current cpu.
+ */
+ time_grq_lock(rq, &flags);
+
+ __setscheduler(idle, rq, SCHED_FIFO, MAX_RT_PRIO - 1);
+
+ activate_idle_task(idle);
+ set_tsk_need_resched(rq->curr);
+
+ grq_unlock_irqrestore(&flags);
+}
+
+/*
+ * Ensures that the idle task is using init_mm right before its cpu goes
+ * offline.
+ */
+void idle_task_exit(void)
+{
+ struct mm_struct *mm = current->active_mm;
+
+ BUG_ON(cpu_online(smp_processor_id()));
+
+ if (mm != &init_mm)
+ switch_mm(mm, &init_mm, current);
+ mmdrop(mm);
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
+#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
+
+static struct ctl_table sd_ctl_dir[] = {
+ {
+ .procname = "sched_domain",
+ .mode = 0555,
+ },
+ {0, },
+};
+
+static struct ctl_table sd_ctl_root[] = {
+ {
+ .ctl_name = CTL_KERN,
+ .procname = "kernel",
+ .mode = 0555,
+ .child = sd_ctl_dir,
+ },
+ {0, },
+};
+
+static struct ctl_table *sd_alloc_ctl_entry(int n)
+{
+ struct ctl_table *entry =
+ kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
+
+ return entry;
+}
+
+static void sd_free_ctl_entry(struct ctl_table **tablep)
+{
+ struct ctl_table *entry;
+
+ /*
+ * In the intermediate directories, both the child directory and
+ * procname are dynamically allocated and could fail but the mode
+ * will always be set. In the lowest directory the names are
+ * static strings and all have proc handlers.
+ */
+ for (entry = *tablep; entry->mode; entry++) {
+ if (entry->child)
+ sd_free_ctl_entry(&entry->child);
+ if (entry->proc_handler == NULL)
+ kfree(entry->procname);
+ }
+
+ kfree(*tablep);
+ *tablep = NULL;
+}
+
+static void
+set_table_entry(struct ctl_table *entry,
+ const char *procname, void *data, int maxlen,
+ mode_t mode, proc_handler *proc_handler)
+{
+ entry->procname = procname;
+ entry->data = data;
+ entry->maxlen = maxlen;
+ entry->mode = mode;
+ entry->proc_handler = proc_handler;
+}
+
+static struct ctl_table *
+sd_alloc_ctl_domain_table(struct sched_domain *sd)
+{
+ struct ctl_table *table = sd_alloc_ctl_entry(13);
+
+ if (table == NULL)
+ return NULL;
+
+ set_table_entry(&table[0], "min_interval", &sd->min_interval,
+ sizeof(long), 0644, proc_doulongvec_minmax);
+ set_table_entry(&table[1], "max_interval", &sd->max_interval,
+ sizeof(long), 0644, proc_doulongvec_minmax);
+ set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[9], "cache_nice_tries",
+ &sd->cache_nice_tries,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[10], "flags", &sd->flags,
+ sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[11], "name", sd->name,
+ CORENAME_MAX_SIZE, 0444, proc_dostring);
+ /* &table[12] is terminator */
+
+ return table;
+}
+
+static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
+{
+ struct ctl_table *entry, *table;
+ struct sched_domain *sd;
+ int domain_num = 0, i;
+ char buf[32];
+
+ for_each_domain(cpu, sd)
+ domain_num++;
+ entry = table = sd_alloc_ctl_entry(domain_num + 1);
+ if (table == NULL)
+ return NULL;
+
+ i = 0;
+ for_each_domain(cpu, sd) {
+ snprintf(buf, 32, "domain%d", i);
+ entry->procname = kstrdup(buf, GFP_KERNEL);
+ entry->mode = 0555;
+ entry->child = sd_alloc_ctl_domain_table(sd);
+ entry++;
+ i++;
+ }
+ return table;
+}
+
+static struct ctl_table_header *sd_sysctl_header;
+static void register_sched_domain_sysctl(void)
+{
+ int i, cpu_num = num_online_cpus();
+ struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
+ char buf[32];
+
+ WARN_ON(sd_ctl_dir[0].child);
+ sd_ctl_dir[0].child = entry;
+
+ if (entry == NULL)
+ return;
+
+ for_each_online_cpu(i) {
+ snprintf(buf, 32, "cpu%d", i);
+ entry->procname = kstrdup(buf, GFP_KERNEL);
+ entry->mode = 0555;
+ entry->child = sd_alloc_ctl_cpu_table(i);
+ entry++;
+ }
+
+ WARN_ON(sd_sysctl_header);
+ sd_sysctl_header = register_sysctl_table(sd_ctl_root);
+}
+
+/* may be called multiple times per register */
+static void unregister_sched_domain_sysctl(void)
+{
+ if (sd_sysctl_header)
+ unregister_sysctl_table(sd_sysctl_header);
+ sd_sysctl_header = NULL;
+ if (sd_ctl_dir[0].child)
+ sd_free_ctl_entry(&sd_ctl_dir[0].child);
+}
+#else
+static void register_sched_domain_sysctl(void)
+{
+}
+static void unregister_sched_domain_sysctl(void)
+{
+}
+#endif
+
+static void set_rq_online(struct rq *rq)
+{
+ if (!rq->online) {
+ cpumask_set_cpu(cpu_of(rq), rq->rd->online);
+ rq->online = 1;
+ }
+}
+
+static void set_rq_offline(struct rq *rq)
+{
+ if (rq->online) {
+ cpumask_clear_cpu(cpu_of(rq), rq->rd->online);
+ rq->online = 0;
+ }
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * This cpu is going down, so walk over the tasklist and find tasks that can
+ * only run on this cpu and remove their affinity. Store their value in
+ * unplugged_mask so it can be restored once their correct cpu is online. No
+ * need to do anything special since they'll just move on next reschedule if
+ * they're running.
+ */
+static void remove_cpu(unsigned long cpu)
+{
+ struct task_struct *p, *t;
+
+ read_lock(&tasklist_lock);
+
+ do_each_thread(t, p) {
+ cpumask_t cpus_remaining;
+
+ cpus_and(cpus_remaining, p->cpus_allowed, cpu_online_map);
+ cpu_clear(cpu, cpus_remaining);