1572 lines (1331 sloc) 42.7 KB
#ifndef _LINUX_SCHED_H
#define _LINUX_SCHED_H
* Define 'struct task_struct' and provide the main scheduler
* APIs (schedule(), wakeup variants, etc.)
#include <uapi/linux/sched.h>
#include <asm/current.h>
#include <linux/pid.h>
#include <linux/sem.h>
#include <linux/shm.h>
#include <linux/kcov.h>
#include <linux/mutex.h>
#include <linux/plist.h>
#include <linux/hrtimer.h>
#include <linux/seccomp.h>
#include <linux/nodemask.h>
#include <linux/rcupdate.h>
#include <linux/resource.h>
#include <linux/latencytop.h>
#include <linux/sched/prio.h>
#include <linux/signal_types.h>
#include <linux/mm_types_task.h>
#include <linux/task_io_accounting.h>
/* task_struct member predeclarations (sorted alphabetically): */
struct audit_context;
struct backing_dev_info;
struct bio_list;
struct blk_plug;
struct cfs_rq;
struct fs_struct;
struct futex_pi_state;
struct io_context;
struct mempolicy;
struct nameidata;
struct nsproxy;
struct perf_event_context;
struct pid_namespace;
struct pipe_inode_info;
struct rcu_node;
struct reclaim_state;
struct robust_list_head;
struct sched_attr;
struct sched_param;
struct seq_file;
struct sighand_struct;
struct signal_struct;
struct task_delay_info;
struct task_group;
* Task state bitmask. NOTE! These bits are also
* encoded in fs/proc/array.c: get_task_state().
* We have two separate sets of flags: task->state
* is about runnability, while task->exit_state are
* about the task exiting. Confusing, but this way
* modifying one set can't modify the other one by
* mistake.
/* Used in tsk->state: */
#define TASK_RUNNING 0
#define __TASK_STOPPED 4
#define __TASK_TRACED 8
/* Used in tsk->exit_state: */
#define EXIT_DEAD 16
#define EXIT_ZOMBIE 32
/* Used in tsk->state again: */
#define TASK_DEAD 64
#define TASK_WAKEKILL 128
#define TASK_WAKING 256
#define TASK_PARKED 512
#define TASK_NOLOAD 1024
#define TASK_NEW 2048
#define TASK_STATE_MAX 4096
/* Convenience macros for the sake of set_current_state: */
/* Convenience macros for the sake of wake_up(): */
/* get_task_state(): */
#define task_is_traced(task) ((task->state & __TASK_TRACED) != 0)
#define task_is_stopped(task) ((task->state & __TASK_STOPPED) != 0)
#define task_is_stopped_or_traced(task) ((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
#define task_contributes_to_load(task) ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
(task->flags & PF_FROZEN) == 0 && \
(task->state & TASK_NOLOAD) == 0)
#define __set_current_state(state_value) \
do { \
current->task_state_change = _THIS_IP_; \
current->state = (state_value); \
} while (0)
#define set_current_state(state_value) \
do { \
current->task_state_change = _THIS_IP_; \
smp_store_mb(current->state, (state_value)); \
} while (0)
* set_current_state() includes a barrier so that the write of current->state
* is correctly serialised wrt the caller's subsequent test of whether to
* actually sleep:
* for (;;) {
* set_current_state(TASK_UNINTERRUPTIBLE);
* if (!need_sleep)
* break;
* schedule();
* }
* __set_current_state(TASK_RUNNING);
* If the caller does not need such serialisation (because, for instance, the
* condition test and condition change and wakeup are under the same lock) then
* use __set_current_state().
* The above is typically ordered against the wakeup, which does:
* need_sleep = false;
* wake_up_state(p, TASK_UNINTERRUPTIBLE);
* Where wake_up_state() (and all other wakeup primitives) imply enough
* barriers to order the store of the variable against wakeup.
* Wakeup will do: if (@state & p->state) p->state = TASK_RUNNING, that is,
* once it observes the TASK_UNINTERRUPTIBLE store the waking CPU can issue a
* TASK_RUNNING store which can collide with __set_current_state(TASK_RUNNING).
* This is obviously fine, since they both store the exact same value.
* Also see the comments of try_to_wake_up().
#define __set_current_state(state_value) do { current->state = (state_value); } while (0)
#define set_current_state(state_value) smp_store_mb(current->state, (state_value))
/* Task command name length: */
#define TASK_COMM_LEN 16
extern cpumask_var_t cpu_isolated_map;
extern void scheduler_tick(void);
extern long schedule_timeout(long timeout);
extern long schedule_timeout_interruptible(long timeout);
extern long schedule_timeout_killable(long timeout);
extern long schedule_timeout_uninterruptible(long timeout);
extern long schedule_timeout_idle(long timeout);
asmlinkage void schedule(void);
extern void schedule_preempt_disabled(void);
extern int __must_check io_schedule_prepare(void);
extern void io_schedule_finish(int token);
extern long io_schedule_timeout(long timeout);
extern void io_schedule(void);
* struct prev_cputime - snaphsot of system and user cputime
* @utime: time spent in user mode
* @stime: time spent in system mode
* @lock: protects the above two fields
* Stores previous user/system time values such that we can guarantee
* monotonicity.
struct prev_cputime {
u64 utime;
u64 stime;
raw_spinlock_t lock;
* struct task_cputime - collected CPU time counts
* @utime: time spent in user mode, in nanoseconds
* @stime: time spent in kernel mode, in nanoseconds
* @sum_exec_runtime: total time spent on the CPU, in nanoseconds
* This structure groups together three kinds of CPU time that are tracked for
* threads and thread groups. Most things considering CPU time want to group
* these counts together and treat all three of them in parallel.
struct task_cputime {
u64 utime;
u64 stime;
unsigned long long sum_exec_runtime;
/* Alternate field names when used on cache expirations: */
#define virt_exp utime
#define prof_exp stime
#define sched_exp sum_exec_runtime
struct sched_info {
/* Cumulative counters: */
/* # of times we have run on this CPU: */
unsigned long pcount;
/* Time spent waiting on a runqueue: */
unsigned long long run_delay;
/* Timestamps: */
/* When did we last run on a CPU? */
unsigned long long last_arrival;
/* When were we last queued to run? */
unsigned long long last_queued;
#endif /* CONFIG_SCHED_INFO */
* Integer metrics need fixed point arithmetic, e.g., sched/fair
* has a few: load, load_avg, util_avg, freq, and capacity.
* We define a basic fixed point arithmetic range, and then formalize
* all these metrics based on that basic range.
struct load_weight {
unsigned long weight;
u32 inv_weight;
* The load_avg/util_avg accumulates an infinite geometric series
* (see __update_load_avg() in kernel/sched/fair.c).
* [load_avg definition]
* load_avg = runnable% * scale_load_down(load)
* where runnable% is the time ratio that a sched_entity is runnable.
* For cfs_rq, it is the aggregated load_avg of all runnable and
* blocked sched_entities.
* load_avg may also take frequency scaling into account:
* load_avg = runnable% * scale_load_down(load) * freq%
* where freq% is the CPU frequency normalized to the highest frequency.
* [util_avg definition]
* util_avg = running% * SCHED_CAPACITY_SCALE
* where running% is the time ratio that a sched_entity is running on
* a CPU. For cfs_rq, it is the aggregated util_avg of all runnable
* and blocked sched_entities.
* util_avg may also factor frequency scaling and CPU capacity scaling:
* util_avg = running% * SCHED_CAPACITY_SCALE * freq% * capacity%
* where freq% is the same as above, and capacity% is the CPU capacity
* normalized to the greatest capacity (due to uarch differences, etc).
* N.B., the above ratios (runnable%, running%, freq%, and capacity%)
* themselves are in the range of [0, 1]. To do fixed point arithmetics,
* we therefore scale them to as large a range as necessary. This is for
* example reflected by util_avg's SCHED_CAPACITY_SCALE.
* [Overflow issue]
* The 64-bit load_sum can have 4353082796 (=2^64/47742/88761) entities
* with the highest load (=88761), always runnable on a single cfs_rq,
* and should not overflow as the number already hits PID_MAX_LIMIT.
* For all other cases (including 32-bit kernels), struct load_weight's
* weight will overflow first before we do, because:
* Max(load_avg) <= Max(load.weight)
* Then it is the load_weight's responsibility to consider overflow
* issues.
struct sched_avg {
u64 last_update_time;
u64 load_sum;
u32 util_sum;
u32 period_contrib;
unsigned long load_avg;
unsigned long util_avg;
struct sched_statistics {
u64 wait_start;
u64 wait_max;
u64 wait_count;
u64 wait_sum;
u64 iowait_count;
u64 iowait_sum;
u64 sleep_start;
u64 sleep_max;
s64 sum_sleep_runtime;
u64 block_start;
u64 block_max;
u64 exec_max;
u64 slice_max;
u64 nr_migrations_cold;
u64 nr_failed_migrations_affine;
u64 nr_failed_migrations_running;
u64 nr_failed_migrations_hot;
u64 nr_forced_migrations;
u64 nr_wakeups;
u64 nr_wakeups_sync;
u64 nr_wakeups_migrate;
u64 nr_wakeups_local;
u64 nr_wakeups_remote;
u64 nr_wakeups_affine;
u64 nr_wakeups_affine_attempts;
u64 nr_wakeups_passive;
u64 nr_wakeups_idle;
struct sched_entity {
/* For load-balancing: */
struct load_weight load;
struct rb_node run_node;
struct list_head group_node;
unsigned int on_rq;
u64 exec_start;
u64 sum_exec_runtime;
u64 vruntime;
u64 prev_sum_exec_runtime;
u64 nr_migrations;
struct sched_statistics statistics;
int depth;
struct sched_entity *parent;
/* rq on which this entity is (to be) queued: */
struct cfs_rq *cfs_rq;
/* rq "owned" by this entity/group: */
struct cfs_rq *my_q;
* Per entity load average tracking.
* Put into separate cache line so it does not
* collide with read-mostly values above.
struct sched_avg avg ____cacheline_aligned_in_smp;
struct sched_rt_entity {
struct list_head run_list;
unsigned long timeout;
unsigned long watchdog_stamp;
unsigned int time_slice;
unsigned short on_rq;
unsigned short on_list;
struct sched_rt_entity *back;
struct sched_rt_entity *parent;
/* rq on which this entity is (to be) queued: */
struct rt_rq *rt_rq;
/* rq "owned" by this entity/group: */
struct rt_rq *my_q;
struct sched_dl_entity {
struct rb_node rb_node;
* Original scheduling parameters. Copied here from sched_attr
* during sched_setattr(), they will remain the same until
* the next sched_setattr().
u64 dl_runtime; /* Maximum runtime for each instance */
u64 dl_deadline; /* Relative deadline of each instance */
u64 dl_period; /* Separation of two instances (period) */
u64 dl_bw; /* dl_runtime / dl_deadline */
* Actual scheduling parameters. Initialized with the values above,
* they are continously updated during task execution. Note that
* the remaining runtime could be < 0 in case we are in overrun.
s64 runtime; /* Remaining runtime for this instance */
u64 deadline; /* Absolute deadline for this instance */
unsigned int flags; /* Specifying the scheduler behaviour */
* Some bool flags:
* @dl_throttled tells if we exhausted the runtime. If so, the
* task has to wait for a replenishment to be performed at the
* next firing of dl_timer.
* @dl_boosted tells if we are boosted due to DI. If so we are
* outside bandwidth enforcement mechanism (but only until we
* exit the critical section);
* @dl_yielded tells if task gave up the CPU before consuming
* all its available runtime during the last job.
int dl_throttled;
int dl_boosted;
int dl_yielded;
* Bandwidth enforcement timer. Each -deadline task has its
* own bandwidth to be enforced, thus we need one timer per task.
struct hrtimer dl_timer;
union rcu_special {
struct {
u8 blocked;
u8 need_qs;
u8 exp_need_qs;
/* Otherwise the compiler can store garbage here: */
u8 pad;
} b; /* Bits. */
u32 s; /* Set of bits. */
enum perf_event_task_context {
perf_invalid_context = -1,
perf_hw_context = 0,
struct wake_q_node {
struct wake_q_node *next;
struct task_struct {
* For reasons of header soup (see current_thread_info()), this
* must be the first element of task_struct.
struct thread_info thread_info;
/* -1 unrunnable, 0 runnable, >0 stopped: */
volatile long state;
void *stack;
atomic_t usage;
/* Per task flags (PF_*), defined further below: */
unsigned int flags;
unsigned int ptrace;
struct llist_node wake_entry;
int on_cpu;
/* Current CPU: */
unsigned int cpu;
unsigned int wakee_flips;
unsigned long wakee_flip_decay_ts;
struct task_struct *last_wakee;
int wake_cpu;
int on_rq;
int prio;
int static_prio;
int normal_prio;
unsigned int rt_priority;
const struct sched_class *sched_class;
struct sched_entity se;
struct sched_rt_entity rt;
struct task_group *sched_task_group;
struct sched_dl_entity dl;
/* List of struct preempt_notifier: */
struct hlist_head preempt_notifiers;
unsigned int btrace_seq;
unsigned int policy;
int nr_cpus_allowed;
cpumask_t cpus_allowed;
int rcu_read_lock_nesting;
union rcu_special rcu_read_unlock_special;
struct list_head rcu_node_entry;
struct rcu_node *rcu_blocked_node;
#endif /* #ifdef CONFIG_PREEMPT_RCU */
unsigned long rcu_tasks_nvcsw;
bool rcu_tasks_holdout;
struct list_head rcu_tasks_holdout_list;
int rcu_tasks_idle_cpu;
#endif /* #ifdef CONFIG_TASKS_RCU */
struct sched_info sched_info;
struct list_head tasks;
struct plist_node pushable_tasks;
struct rb_node pushable_dl_tasks;
struct mm_struct *mm;
struct mm_struct *active_mm;
/* Per-thread vma caching: */
struct vmacache vmacache;
struct task_rss_stat rss_stat;
int exit_state;
int exit_code;
int exit_signal;
/* The signal sent when the parent dies: */
int pdeath_signal;
/* JOBCTL_*, siglock protected: */
unsigned long jobctl;
/* Used for emulating ABI behavior of previous Linux versions: */
unsigned int personality;
/* Scheduler bits, serialized by scheduler locks: */
unsigned sched_reset_on_fork:1;
unsigned sched_contributes_to_load:1;
unsigned sched_migrated:1;
unsigned sched_remote_wakeup:1;
/* Force alignment to the next boundary: */
unsigned :0;
/* Unserialized, strictly 'current' */
/* Bit to tell LSMs we're in execve(): */
unsigned in_execve:1;
unsigned in_iowait:1;
unsigned restore_sigmask:1;
unsigned memcg_may_oom:1;
unsigned memcg_kmem_skip_account:1;
unsigned brk_randomized:1;
/* disallow userland-initiated cgroup migration */
unsigned no_cgroup_migration:1;
unsigned long atomic_flags; /* Flags requiring atomic access. */
struct restart_block restart_block;
pid_t pid;
pid_t tgid;
/* Canary value for the -fstack-protector GCC feature: */
unsigned long stack_canary;
* Pointers to the (original) parent process, youngest child, younger sibling,
* older sibling, respectively. (p->father can be replaced with
* p->real_parent->pid)
/* Real parent process: */
struct task_struct __rcu *real_parent;
/* Recipient of SIGCHLD, wait4() reports: */
struct task_struct __rcu *parent;
* Children/sibling form the list of natural children:
struct list_head children;
struct list_head sibling;
struct task_struct *group_leader;
* 'ptraced' is the list of tasks this task is using ptrace() on.
* This includes both natural children and PTRACE_ATTACH targets.
* 'ptrace_entry' is this task's link on the p->parent->ptraced list.
struct list_head ptraced;
struct list_head ptrace_entry;
/* PID/PID hash table linkage. */
struct pid_link pids[PIDTYPE_MAX];
struct list_head thread_group;
struct list_head thread_node;
struct completion *vfork_done;
int __user *set_child_tid;
int __user *clear_child_tid;
u64 utime;
u64 stime;
u64 utimescaled;
u64 stimescaled;
u64 gtime;
struct prev_cputime prev_cputime;
seqcount_t vtime_seqcount;
unsigned long long vtime_snap;
enum {
/* Task is sleeping or running in a CPU with VTIME inactive: */
/* Task runs in userspace in a CPU with VTIME active: */
/* Task runs in kernelspace in a CPU with VTIME active: */
} vtime_snap_whence;
atomic_t tick_dep_mask;
/* Context switch counts: */
unsigned long nvcsw;
unsigned long nivcsw;
/* Monotonic time in nsecs: */
u64 start_time;
/* Boot based time in nsecs: */
u64 real_start_time;
/* MM fault and swap info: this can arguably be seen as either mm-specific or thread-specific: */
unsigned long min_flt;
unsigned long maj_flt;
struct task_cputime cputime_expires;
struct list_head cpu_timers[3];
/* Process credentials: */
/* Tracer's credentials at attach: */
const struct cred __rcu *ptracer_cred;
/* Objective and real subjective task credentials (COW): */
const struct cred __rcu *real_cred;
/* Effective (overridable) subjective task credentials (COW): */
const struct cred __rcu *cred;
* executable name, excluding path.
* - normally initialized setup_new_exec()
* - access it with [gs]et_task_comm()
* - lock it with task_lock()
char comm[TASK_COMM_LEN];
struct nameidata *nameidata;
struct sysv_sem sysvsem;
struct sysv_shm sysvshm;
unsigned long last_switch_count;
/* Filesystem information: */
struct fs_struct *fs;
/* Open file information: */
struct files_struct *files;
/* Namespaces: */
struct nsproxy *nsproxy;
/* Signal handlers: */
struct signal_struct *signal;
struct sighand_struct *sighand;
sigset_t blocked;
sigset_t real_blocked;
/* Restored if set_restore_sigmask() was used: */
sigset_t saved_sigmask;
struct sigpending pending;
unsigned long sas_ss_sp;
size_t sas_ss_size;
unsigned int sas_ss_flags;
struct callback_head *task_works;
struct audit_context *audit_context;
kuid_t loginuid;
unsigned int sessionid;
struct seccomp seccomp;
/* Thread group tracking: */
u32 parent_exec_id;
u32 self_exec_id;
/* Protection against (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, mempolicy: */
spinlock_t alloc_lock;
/* Protection of the PI data structures: */
raw_spinlock_t pi_lock;
struct wake_q_node wake_q;
/* PI waiters blocked on a rt_mutex held by this task: */
struct rb_root pi_waiters;
struct rb_node *pi_waiters_leftmost;
/* Deadlock detection and priority inheritance handling: */
struct rt_mutex_waiter *pi_blocked_on;
/* Mutex deadlock detection: */
struct mutex_waiter *blocked_on;
unsigned int irq_events;
unsigned long hardirq_enable_ip;
unsigned long hardirq_disable_ip;
unsigned int hardirq_enable_event;
unsigned int hardirq_disable_event;
int hardirqs_enabled;
int hardirq_context;
unsigned long softirq_disable_ip;
unsigned long softirq_enable_ip;
unsigned int softirq_disable_event;
unsigned int softirq_enable_event;
int softirqs_enabled;
int softirq_context;
# define MAX_LOCK_DEPTH 48UL
u64 curr_chain_key;
int lockdep_depth;
unsigned int lockdep_recursion;
struct held_lock held_locks[MAX_LOCK_DEPTH];
gfp_t lockdep_reclaim_gfp;
unsigned int in_ubsan;
/* Journalling filesystem info: */
void *journal_info;
/* Stacked block device info: */
struct bio_list *bio_list;
/* Stack plugging: */
struct blk_plug *plug;
/* VM state: */
struct reclaim_state *reclaim_state;
struct backing_dev_info *backing_dev_info;
struct io_context *io_context;
/* Ptrace state: */
unsigned long ptrace_message;
siginfo_t *last_siginfo;
struct task_io_accounting ioac;
/* Accumulated RSS usage: */
u64 acct_rss_mem1;
/* Accumulated virtual memory usage: */
u64 acct_vm_mem1;
/* stime + utime since last update: */
u64 acct_timexpd;
/* Protected by ->alloc_lock: */
nodemask_t mems_allowed;
/* Seqence number to catch updates: */
seqcount_t mems_allowed_seq;
int cpuset_mem_spread_rotor;
int cpuset_slab_spread_rotor;
/* Control Group info protected by css_set_lock: */
struct css_set __rcu *cgroups;
/* cg_list protected by css_set_lock and tsk->alloc_lock: */
struct list_head cg_list;
int closid;
struct robust_list_head __user *robust_list;
struct compat_robust_list_head __user *compat_robust_list;
struct list_head pi_state_list;
struct futex_pi_state *pi_state_cache;
struct perf_event_context *perf_event_ctxp[perf_nr_task_contexts];
struct mutex perf_event_mutex;
struct list_head perf_event_list;
unsigned long preempt_disable_ip;
/* Protected by alloc_lock: */
struct mempolicy *mempolicy;
short il_next;
short pref_node_fork;
int numa_scan_seq;
unsigned int numa_scan_period;
unsigned int numa_scan_period_max;
int numa_preferred_nid;
unsigned long numa_migrate_retry;
/* Migration stamp: */
u64 node_stamp;
u64 last_task_numa_placement;
u64 last_sum_exec_runtime;
struct callback_head numa_work;
struct list_head numa_entry;
struct numa_group *numa_group;
* numa_faults is an array split into four regions:
* faults_memory, faults_cpu, faults_memory_buffer, faults_cpu_buffer
* in this precise order.
* faults_memory: Exponential decaying average of faults on a per-node
* basis. Scheduling placement decisions are made based on these
* counts. The values remain static for the duration of a PTE scan.
* faults_cpu: Track the nodes the process was running on when a NUMA
* hinting fault was incurred.
* faults_memory_buffer and faults_cpu_buffer: Record faults per node
* during the current scan window. When the scan completes, the counts
* in faults_memory and faults_cpu decay and these values are copied.
unsigned long *numa_faults;
unsigned long total_numa_faults;
* numa_faults_locality tracks if faults recorded during the last
* scan window were remote/local or failed to migrate. The task scan
* period is adapted based on the locality of the faults with different
* weights depending on whether they were shared or private faults
unsigned long numa_faults_locality[3];
unsigned long numa_pages_migrated;
struct tlbflush_unmap_batch tlb_ubc;
struct rcu_head rcu;
/* Cache last used pipe for splice(): */
struct pipe_inode_info *splice_pipe;
struct page_frag task_frag;
struct task_delay_info *delays;
int make_it_fail;
* When (nr_dirtied >= nr_dirtied_pause), it's time to call
* balance_dirty_pages() for a dirty throttling pause:
int nr_dirtied;
int nr_dirtied_pause;
/* Start of a write-and-pause period: */
unsigned long dirty_paused_when;
int latency_record_count;
struct latency_record latency_record[LT_SAVECOUNT];
* Time slack values; these are used to round up poll() and
* select() etc timeout values. These are in nanoseconds.
u64 timer_slack_ns;
u64 default_timer_slack_ns;
unsigned int kasan_depth;
/* Index of current stored address in ret_stack: */
int curr_ret_stack;
/* Stack of return addresses for return function tracing: */
struct ftrace_ret_stack *ret_stack;
/* Timestamp for last schedule: */
unsigned long long ftrace_timestamp;
* Number of functions that haven't been traced
* because of depth overrun:
atomic_t trace_overrun;
/* Pause tracing: */
atomic_t tracing_graph_pause;
/* State flags for use by tracers: */
unsigned long trace;
/* Bitmask and counter of trace recursion: */
unsigned long trace_recursion;
#endif /* CONFIG_TRACING */
/* Coverage collection mode enabled for this task (0 if disabled): */
enum kcov_mode kcov_mode;
/* Size of the kcov_area: */
unsigned int kcov_size;
/* Buffer for coverage collection: */
void *kcov_area;
/* KCOV descriptor wired with this task or NULL: */
struct kcov *kcov;
struct mem_cgroup *memcg_in_oom;
gfp_t memcg_oom_gfp_mask;
int memcg_oom_order;
/* Number of pages to reclaim on returning to userland: */
unsigned int memcg_nr_pages_over_high;
struct uprobe_task *utask;
unsigned int sequential_io;
unsigned int sequential_io_avg;
unsigned long task_state_change;
int pagefault_disabled;
struct task_struct *oom_reaper_list;
struct vm_struct *stack_vm_area;
/* A live task holds one reference: */
atomic_t stack_refcount;
/* CPU-specific state of this task: */
struct thread_struct thread;
* WARNING: on x86, 'thread_struct' contains a variable-sized
* structure. It *MUST* be at the end of 'task_struct'.
* Do not put anything below here!
static inline struct pid *task_pid(struct task_struct *task)
return task->pids[PIDTYPE_PID].pid;
static inline struct pid *task_tgid(struct task_struct *task)
return task->group_leader->pids[PIDTYPE_PID].pid;
* Without tasklist or RCU lock it is not safe to dereference
* the result of task_pgrp/task_session even if task == current,
* we can race with another thread doing sys_setsid/sys_setpgid.
static inline struct pid *task_pgrp(struct task_struct *task)
return task->group_leader->pids[PIDTYPE_PGID].pid;
static inline struct pid *task_session(struct task_struct *task)
return task->group_leader->pids[PIDTYPE_SID].pid;
* the helpers to get the task's different pids as they are seen
* from various namespaces
* task_xid_nr() : global id, i.e. the id seen from the init namespace;
* task_xid_vnr() : virtual id, i.e. the id seen from the pid namespace of
* current.
* task_xid_nr_ns() : id seen from the ns specified;
* set_task_vxid() : assigns a virtual id to a task;
* see also pid_nr() etc in include/linux/pid.h
pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, struct pid_namespace *ns);
static inline pid_t task_pid_nr(struct task_struct *tsk)
return tsk->pid;
static inline pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
static inline pid_t task_pid_vnr(struct task_struct *tsk)
return __task_pid_nr_ns(tsk, PIDTYPE_PID, NULL);
static inline pid_t task_tgid_nr(struct task_struct *tsk)
return tsk->tgid;
extern pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);
static inline pid_t task_tgid_vnr(struct task_struct *tsk)
return pid_vnr(task_tgid(tsk));
* pid_alive - check that a task structure is not stale
* @p: Task structure to be checked.
* Test if a process is not yet dead (at most zombie state)
* If pid_alive fails, then pointers within the task structure
* can be stale and must not be dereferenced.
* Return: 1 if the process is alive. 0 otherwise.
static inline int pid_alive(const struct task_struct *p)
return p->pids[PIDTYPE_PID].pid != NULL;
static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
pid_t pid = 0;
if (pid_alive(tsk))
pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
return pid;
static inline pid_t task_ppid_nr(const struct task_struct *tsk)
return task_ppid_nr_ns(tsk, &init_pid_ns);
static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
return __task_pid_nr_ns(tsk, PIDTYPE_PGID, ns);
static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
return __task_pid_nr_ns(tsk, PIDTYPE_PGID, NULL);
static inline pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
return __task_pid_nr_ns(tsk, PIDTYPE_SID, ns);
static inline pid_t task_session_vnr(struct task_struct *tsk)
return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
/* Obsolete, do not use: */
static inline pid_t task_pgrp_nr(struct task_struct *tsk)
return task_pgrp_nr_ns(tsk, &init_pid_ns);
* is_global_init - check if a task structure is init. Since init
* is free to have sub-threads we need to check tgid.
* @tsk: Task structure to be checked.
* Check if a task structure is the first user space task the kernel created.
* Return: 1 if the task structure is init. 0 otherwise.
static inline int is_global_init(struct task_struct *tsk)
return task_tgid_nr(tsk) == 1;
extern struct pid *cad_pid;
* Per process flags
#define PF_IDLE 0x00000002 /* I am an IDLE thread */
#define PF_EXITING 0x00000004 /* Getting shut down */
#define PF_EXITPIDONE 0x00000008 /* PI exit done on shut down */
#define PF_VCPU 0x00000010 /* I'm a virtual CPU */
#define PF_WQ_WORKER 0x00000020 /* I'm a workqueue worker */
#define PF_FORKNOEXEC 0x00000040 /* Forked but didn't exec */
#define PF_MCE_PROCESS 0x00000080 /* Process policy on mce errors */
#define PF_SUPERPRIV 0x00000100 /* Used super-user privileges */
#define PF_DUMPCORE 0x00000200 /* Dumped core */
#define PF_SIGNALED 0x00000400 /* Killed by a signal */
#define PF_MEMALLOC 0x00000800 /* Allocating memory */
#define PF_NPROC_EXCEEDED 0x00001000 /* set_user() noticed that RLIMIT_NPROC was exceeded */
#define PF_USED_MATH 0x00002000 /* If unset the fpu must be initialized before use */
#define PF_USED_ASYNC 0x00004000 /* Used async_schedule*(), used by module init */
#define PF_NOFREEZE 0x00008000 /* This thread should not be frozen */
#define PF_FROZEN 0x00010000 /* Frozen for system suspend */
#define PF_FSTRANS 0x00020000 /* Inside a filesystem transaction */
#define PF_KSWAPD 0x00040000 /* I am kswapd */
#define PF_MEMALLOC_NOIO 0x00080000 /* Allocating memory without IO involved */
#define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */
#define PF_KTHREAD 0x00200000 /* I am a kernel thread */
#define PF_RANDOMIZE 0x00400000 /* Randomize virtual address space */
#define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */
#define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_allowed */
#define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */
#define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */
#define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezable */
#define PF_SUSPEND_TASK 0x80000000 /* This thread called freeze_processes() and should not be frozen */
* Only the _current_ task can read/write to tsk->flags, but other
* tasks can access tsk->flags in readonly mode for example
* with tsk_used_math (like during threaded core dumping).
* There is however an exception to this rule during ptrace
* or during fork: the ptracer task is allowed to write to the
* child->flags of its traced child (same goes for fork, the parent
* can write to the child->flags), because we're guaranteed the
* child is not running and in turn not changing child->flags
* at the same time the parent does it.
#define clear_stopped_child_used_math(child) do { (child)->flags &= ~PF_USED_MATH; } while (0)
#define set_stopped_child_used_math(child) do { (child)->flags |= PF_USED_MATH; } while (0)
#define clear_used_math() clear_stopped_child_used_math(current)
#define set_used_math() set_stopped_child_used_math(current)
#define conditional_stopped_child_used_math(condition, child) \
do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= (condition) ? PF_USED_MATH : 0; } while (0)
#define conditional_used_math(condition) conditional_stopped_child_used_math(condition, current)
#define copy_to_stopped_child_used_math(child) \
do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= current->flags & PF_USED_MATH; } while (0)
/* NOTE: this will return 0 or PF_USED_MATH, it will never return 1 */
#define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
#define used_math() tsk_used_math(current)
/* Per-process atomic flags. */
#define PFA_NO_NEW_PRIVS 0 /* May not gain new privileges. */
#define PFA_SPREAD_PAGE 1 /* Spread page cache over cpuset */
#define PFA_SPREAD_SLAB 2 /* Spread some slab caches over cpuset */
#define PFA_LMK_WAITING 3 /* Lowmemorykiller is waiting */
#define TASK_PFA_TEST(name, func) \
static inline bool task_##func(struct task_struct *p) \
{ return test_bit(PFA_##name, &p->atomic_flags); }
#define TASK_PFA_SET(name, func) \
static inline void task_set_##func(struct task_struct *p) \
{ set_bit(PFA_##name, &p->atomic_flags); }
#define TASK_PFA_CLEAR(name, func) \
static inline void task_clear_##func(struct task_struct *p) \
{ clear_bit(PFA_##name, &p->atomic_flags); }
TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
static inline void
tsk_restore_flags(struct task_struct *task, unsigned long orig_flags, unsigned long flags)
task->flags &= ~flags;
task->flags |= orig_flags & flags;
extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);
extern int task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed);
extern void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask);
extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask);
static inline void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
static inline int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
if (!cpumask_test_cpu(0, new_mask))
return -EINVAL;
return 0;
#ifndef cpu_relax_yield
#define cpu_relax_yield() cpu_relax()
extern int yield_to(struct task_struct *p, bool preempt);
extern void set_user_nice(struct task_struct *p, long nice);
extern int task_prio(const struct task_struct *p);
* task_nice - return the nice value of a given task.
* @p: the task in question.
* Return: The nice value [ -20 ... 0 ... 19 ].
static inline int task_nice(const struct task_struct *p)
return PRIO_TO_NICE((p)->static_prio);
extern int can_nice(const struct task_struct *p, const int nice);
extern int task_curr(const struct task_struct *p);
extern int idle_cpu(int cpu);
extern int sched_setscheduler(struct task_struct *, int, const struct sched_param *);
extern int sched_setscheduler_nocheck(struct task_struct *, int, const struct sched_param *);
extern int sched_setattr(struct task_struct *, const struct sched_attr *);
extern struct task_struct *idle_task(int cpu);
* is_idle_task - is the specified task an idle task?
* @p: the task in question.
* Return: 1 if @p is an idle task. 0 otherwise.
static inline bool is_idle_task(const struct task_struct *p)
return !!(p->flags & PF_IDLE);
extern struct task_struct *curr_task(int cpu);
extern void ia64_set_curr_task(int cpu, struct task_struct *p);
void yield(void);
union thread_union {
struct thread_info thread_info;
unsigned long stack[THREAD_SIZE/sizeof(long)];
static inline struct thread_info *task_thread_info(struct task_struct *task)
return &task->thread_info;
#elif !defined(__HAVE_THREAD_FUNCTIONS)
# define task_thread_info(task) ((struct thread_info *)(task)->stack)
* find a task by one of its numerical ids
* find_task_by_pid_ns():
* finds a task by its pid in the specified namespace
* find_task_by_vpid():
* finds a task by its virtual pid
* see also find_vpid() etc in include/linux/pid.h
extern struct task_struct *find_task_by_vpid(pid_t nr);
extern struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns);
extern int wake_up_state(struct task_struct *tsk, unsigned int state);
extern int wake_up_process(struct task_struct *tsk);
extern void wake_up_new_task(struct task_struct *tsk);
extern void kick_process(struct task_struct *tsk);
static inline void kick_process(struct task_struct *tsk) { }
extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
static inline void set_task_comm(struct task_struct *tsk, const char *from)
__set_task_comm(tsk, from, false);
extern char *get_task_comm(char *to, struct task_struct *tsk);
void scheduler_ipi(void);
extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
static inline void scheduler_ipi(void) { }
static inline unsigned long wait_task_inactive(struct task_struct *p, long match_state)
return 1;
* Set thread flags in other task's structures.
* See asm/thread_info.h for TIF_xxxx flags available:
static inline void set_tsk_thread_flag(struct task_struct *tsk, int flag)
set_ti_thread_flag(task_thread_info(tsk), flag);
static inline void clear_tsk_thread_flag(struct task_struct *tsk, int flag)
clear_ti_thread_flag(task_thread_info(tsk), flag);
static inline int test_and_set_tsk_thread_flag(struct task_struct *tsk, int flag)
return test_and_set_ti_thread_flag(task_thread_info(tsk), flag);
static inline int test_and_clear_tsk_thread_flag(struct task_struct *tsk, int flag)
return test_and_clear_ti_thread_flag(task_thread_info(tsk), flag);
static inline int test_tsk_thread_flag(struct task_struct *tsk, int flag)
return test_ti_thread_flag(task_thread_info(tsk), flag);
static inline void set_tsk_need_resched(struct task_struct *tsk)
static inline void clear_tsk_need_resched(struct task_struct *tsk)
static inline int test_tsk_need_resched(struct task_struct *tsk)
return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
* cond_resched() and cond_resched_lock(): latency reduction via
* explicit rescheduling in places that are safe. The return
* value indicates whether a reschedule was done in fact.
* cond_resched_lock() will drop the spinlock before scheduling,
* cond_resched_softirq() will enable bhs before scheduling.
extern int _cond_resched(void);
static inline int _cond_resched(void) { return 0; }
#define cond_resched() ({ \
___might_sleep(__FILE__, __LINE__, 0); \
_cond_resched(); \
extern int __cond_resched_lock(spinlock_t *lock);
#define cond_resched_lock(lock) ({ \
___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\
__cond_resched_lock(lock); \
extern int __cond_resched_softirq(void);
#define cond_resched_softirq() ({ \
___might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET); \
__cond_resched_softirq(); \
static inline void cond_resched_rcu(void)
* Does a critical section need to be broken due to another
* task waiting?: (technically does not depend on CONFIG_PREEMPT,
* but a general need for low latency)
static inline int spin_needbreak(spinlock_t *lock)
return spin_is_contended(lock);
return 0;
static __always_inline bool need_resched(void)
return unlikely(tif_need_resched());
* Wrappers for p->thread_info->cpu access. No-op on UP.
static inline unsigned int task_cpu(const struct task_struct *p)
return p->cpu;
return task_thread_info(p)->cpu;
extern void set_task_cpu(struct task_struct *p, unsigned int cpu);
static inline unsigned int task_cpu(const struct task_struct *p)
return 0;
static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
#endif /* CONFIG_SMP */
* In order to reduce various lock holder preemption latencies provide an
* interface to see if a vCPU is currently running or not.
* This allows us to terminate optimistic spin loops and block, analogous to
* the native optimistic spin heuristic of testing if the lock owner task is
* running or not.
#ifndef vcpu_is_preempted
# define vcpu_is_preempted(cpu) false
extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask);
extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
#ifndef TASK_SIZE_OF