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/*
* RT Mutexes: blocking mutual exclusion locks with PI support
*
* started by Ingo Molnar and Thomas Gleixner:
*
* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
*
* This file contains the private data structure and API definitions.
*/
#ifndef __KERNEL_RTMUTEX_COMMON_H
#define __KERNEL_RTMUTEX_COMMON_H
#include <linux/rtmutex.h>
/*
* The rtmutex in kernel tester is independent of rtmutex debugging. We
* call schedule_rt_mutex_test() instead of schedule() for the tasks which
* belong to the tester. That way we can delay the wakeup path of those
* threads to provoke lock stealing and testing of complex boosting scenarios.
*/
#ifdef CONFIG_RT_MUTEX_TESTER
extern void schedule_rt_mutex_test(struct rt_mutex *lock);
#define schedule_rt_mutex(_lock) \
do { \
if (!(current->flags & PF_MUTEX_TESTER)) \
schedule(); \
else \
schedule_rt_mutex_test(_lock); \
} while (0)
#else
# define schedule_rt_mutex(_lock) schedule()
#endif
/*
* This is the control structure for tasks blocked on a rt_mutex,
* which is allocated on the kernel stack on of the blocked task.
*
* @list_entry: pi node to enqueue into the mutex waiters list
* @pi_list_entry: pi node to enqueue into the mutex owner waiters list
* @task: task reference to the blocked task
*/
struct rt_mutex_waiter {
struct plist_node list_entry;
struct plist_node pi_list_entry;
struct task_struct *task;
struct rt_mutex *lock;
#ifdef CONFIG_DEBUG_RT_MUTEXES
unsigned long ip;
pid_t deadlock_task_pid;
struct rt_mutex *deadlock_lock;
#endif
};
/*
* Various helpers to access the waiters-plist:
*/
static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
{
return !plist_head_empty(&lock->wait_list);
}
static inline struct rt_mutex_waiter *
rt_mutex_top_waiter(struct rt_mutex *lock)
{
struct rt_mutex_waiter *w;
w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter,
list_entry);
BUG_ON(w->lock != lock);
return w;
}
static inline int task_has_pi_waiters(struct task_struct *p)
{
return !plist_head_empty(&p->pi_waiters);
}
static inline struct rt_mutex_waiter *
task_top_pi_waiter(struct task_struct *p)
{
return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter,
pi_list_entry);
}
/*
* lock->owner state tracking:
*/
#define RT_MUTEX_OWNER_PENDING 1UL
#define RT_MUTEX_HAS_WAITERS 2UL
#define RT_MUTEX_OWNER_MASKALL 3UL
static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
{
return (struct task_struct *)
((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
}
static inline struct task_struct *rt_mutex_real_owner(struct rt_mutex *lock)
{
return (struct task_struct *)
((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
}
static inline unsigned long rt_mutex_owner_pending(struct rt_mutex *lock)
{
return (unsigned long)lock->owner & RT_MUTEX_OWNER_PENDING;
}
/*
* We can speed up the acquire/release, if the architecture
* supports cmpxchg and if there's no debugging state to be set up
*/
#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES)
# define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c)
static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
{
unsigned long owner, *p = (unsigned long *) &lock->owner;
do {
owner = *p;
} while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner);
}
#else
# define rt_mutex_cmpxchg(l,c,n) (0)
static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
{
lock->owner = (struct task_struct *)
((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
}
#endif
/*
* PI-futex support (proxy locking functions, etc.):
*/
extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
struct task_struct *proxy_owner);
extern void rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner,
unsigned long mask);
extern void __rt_mutex_adjust_prio(struct task_struct *task);
extern int rt_mutex_adjust_prio_chain(struct task_struct *task,
int deadlock_detect,
struct rt_mutex *orig_lock,
struct rt_mutex_waiter *orig_waiter,
struct task_struct *top_task);
extern void remove_waiter(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter);
#endif
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