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Commit e7241d77 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 

* 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  spinlock: Add missing __raw_spin_lock_flags() stub for UP
  mutex: add atomic_dec_and_mutex_lock(), fix
  locking, rtmutex.c: Documentation cleanup
  mutex: add atomic_dec_and_mutex_lock()
parents 3f6280dd 04dce7d9

include/linux/mutex.h

+1 −0
Original line number Diff line number Diff line
@@ -150,5 +150,6 @@ extern int __must_check mutex_lock_killable(struct mutex *lock); 
 */

extern int mutex_trylock(struct mutex *lock);

extern void mutex_unlock(struct mutex *lock);

extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);



#endif

include/linux/spinlock_up.h

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ static inline void __raw_spin_unlock(raw_spinlock_t *lock) 
#define __raw_spin_is_locked(lock)	((void)(lock), 0)

/* for sched.c and kernel_lock.c: */

# define __raw_spin_lock(lock)		do { (void)(lock); } while (0)

# define __raw_spin_lock_flags(lock, flags)	do { (void)(lock); } while (0)

# define __raw_spin_unlock(lock)	do { (void)(lock); } while (0)

# define __raw_spin_trylock(lock)	({ (void)(lock); 1; })

#endif /* DEBUG_SPINLOCK */

kernel/mutex.c

+24 −1
Original line number Diff line number Diff line
@@ -473,5 +473,28 @@ int __sched mutex_trylock(struct mutex *lock) 


	return ret;

}



EXPORT_SYMBOL(mutex_trylock);



/**

 * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0

 * @cnt: the atomic which we are to dec

 * @lock: the mutex to return holding if we dec to 0

 *

 * return true and hold lock if we dec to 0, return false otherwise

 */

int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)

{

	/* dec if we can't possibly hit 0 */

	if (atomic_add_unless(cnt, -1, 1))

		return 0;

	/* we might hit 0, so take the lock */

	mutex_lock(lock);

	if (!atomic_dec_and_test(cnt)) {

		/* when we actually did the dec, we didn't hit 0 */

		mutex_unlock(lock);

		return 0;

	}

	/* we hit 0, and we hold the lock */

	return 1;

}

EXPORT_SYMBOL(atomic_dec_and_mutex_lock);

kernel/rtmutex.c

+4 −4
Original line number Diff line number Diff line
@@ -891,7 +891,7 @@ int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock, 
EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);



/**

 * rt_mutex_lock_interruptible_ktime - lock a rt_mutex interruptible

 * rt_mutex_timed_lock - lock a rt_mutex interruptible

 *			the timeout structure is provided

 *			by the caller

 *
@@ -940,7 +940,7 @@ void __sched rt_mutex_unlock(struct rt_mutex *lock) 
}

EXPORT_SYMBOL_GPL(rt_mutex_unlock);



/***

/**

 * rt_mutex_destroy - mark a mutex unusable

 * @lock: the mutex to be destroyed

 *