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Commit 8292c9e1 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
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locking, semaphores: Annotate inner lock as raw 



There is no reason to have the spin_lock protecting the semaphore
preemptible on -rt. Annotate it as a raw_spinlock.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

( On rt this also solves lockdep complaining about the
  rt_mutex.wait_lock being not initialized. )

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ee30a7b2

include/linux/semaphore.h

+2 −2
Original line number Diff line number Diff line
@@ -14,14 +14,14 @@ 


/* Please don't access any members of this structure directly */

struct semaphore {

	spinlock_t		lock;

	raw_spinlock_t		lock;

	unsigned int		count;

	struct list_head	wait_list;

};



#define __SEMAPHORE_INITIALIZER(name, n)				\

{									\

	.lock		= __SPIN_LOCK_UNLOCKED((name).lock),		\

	.lock		= __RAW_SPIN_LOCK_UNLOCKED((name).lock),	\

	.count		= n,						\

	.wait_list	= LIST_HEAD_INIT((name).wait_list),		\

}

kernel/semaphore.c

+14 −14
Original line number Diff line number Diff line
@@ -54,12 +54,12 @@ void down(struct semaphore *sem) 
{

	unsigned long flags;



	spin_lock_irqsave(&sem->lock, flags);

	raw_spin_lock_irqsave(&sem->lock, flags);

	if (likely(sem->count > 0))

		sem->count--;

	else

		__down(sem);

	spin_unlock_irqrestore(&sem->lock, flags);

	raw_spin_unlock_irqrestore(&sem->lock, flags);

}

EXPORT_SYMBOL(down);
@@ -77,12 +77,12 @@ int down_interruptible(struct semaphore *sem) 
	unsigned long flags;

	int result = 0;



	spin_lock_irqsave(&sem->lock, flags);

	raw_spin_lock_irqsave(&sem->lock, flags);

	if (likely(sem->count > 0))

		sem->count--;

	else

		result = __down_interruptible(sem);

	spin_unlock_irqrestore(&sem->lock, flags);

	raw_spin_unlock_irqrestore(&sem->lock, flags);



	return result;

}
@@ -103,12 +103,12 @@ int down_killable(struct semaphore *sem) 
	unsigned long flags;

	int result = 0;



	spin_lock_irqsave(&sem->lock, flags);

	raw_spin_lock_irqsave(&sem->lock, flags);

	if (likely(sem->count > 0))

		sem->count--;

	else

		result = __down_killable(sem);

	spin_unlock_irqrestore(&sem->lock, flags);

	raw_spin_unlock_irqrestore(&sem->lock, flags);



	return result;

}
@@ -132,11 +132,11 @@ int down_trylock(struct semaphore *sem) 
	unsigned long flags;

	int count;



	spin_lock_irqsave(&sem->lock, flags);

	raw_spin_lock_irqsave(&sem->lock, flags);

	count = sem->count - 1;

	if (likely(count >= 0))

		sem->count = count;

	spin_unlock_irqrestore(&sem->lock, flags);

	raw_spin_unlock_irqrestore(&sem->lock, flags);



	return (count < 0);

}
@@ -157,12 +157,12 @@ int down_timeout(struct semaphore *sem, long jiffies) 
	unsigned long flags;

	int result = 0;



	spin_lock_irqsave(&sem->lock, flags);

	raw_spin_lock_irqsave(&sem->lock, flags);

	if (likely(sem->count > 0))

		sem->count--;

	else

		result = __down_timeout(sem, jiffies);

	spin_unlock_irqrestore(&sem->lock, flags);

	raw_spin_unlock_irqrestore(&sem->lock, flags);



	return result;

}
@@ -179,12 +179,12 @@ void up(struct semaphore *sem) 
{

	unsigned long flags;



	spin_lock_irqsave(&sem->lock, flags);

	raw_spin_lock_irqsave(&sem->lock, flags);

	if (likely(list_empty(&sem->wait_list)))

		sem->count++;

	else

		__up(sem);

	spin_unlock_irqrestore(&sem->lock, flags);

	raw_spin_unlock_irqrestore(&sem->lock, flags);

}

EXPORT_SYMBOL(up);
@@ -217,9 +217,9 @@ static inline int __sched __down_common(struct semaphore *sem, long state, 
		if (timeout <= 0)

			goto timed_out;

		__set_task_state(task, state);

		spin_unlock_irq(&sem->lock);

		raw_spin_unlock_irq(&sem->lock);

		timeout = schedule_timeout(timeout);

		spin_lock_irq(&sem->lock);

		raw_spin_lock_irq(&sem->lock);

		if (waiter.up)

			return 0;

	}