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Commit 4b16bfbf authored by Zoltan Menyhart's avatar Zoltan Menyhart Committed by Tony Luck
Browse files

[IA64] Fix bug in ia64 specific down() function 



Chen, Kenneth W wrote:
> The memory order semantics for include/asm-ia64/semaphore.h:down()
> doesn't look right.  It is using atomic_dec_return, which eventually
> translate into ia64_fetch_and_add() that uses release semantics.
> Shouldn't it use acquire semantics?

Use ia64_fetchadd() instead of atomic_dec_return()

Acked-by: default avatarKen Chen <kenneth.w.chen@intel.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 8d08aed8

include/asm-ia64/semaphore.h

+4 −4
Original line number Original line Diff line number Diff line
@@ -61,7 +61,7 @@ static inline void 
down (struct semaphore *sem)

down (struct semaphore *sem)

{

{

	might_sleep();

	might_sleep();

	if (atomic_dec_return(&sem->count) < 0)

	if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)

		__down(sem);

		__down(sem);

}

}
@@ -75,7 +75,7 @@ down_interruptible (struct semaphore * sem) 
	int ret = 0;

	int ret = 0;





	might_sleep();

	might_sleep();

	if (atomic_dec_return(&sem->count) < 0)

	if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)

		ret = __down_interruptible(sem);

		ret = __down_interruptible(sem);

	return ret;

	return ret;

}

}
@@ -85,7 +85,7 @@ down_trylock (struct semaphore *sem) 
{

{

	int ret = 0;

	int ret = 0;





	if (atomic_dec_return(&sem->count) < 0)

	if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)

		ret = __down_trylock(sem);

		ret = __down_trylock(sem);

	return ret;

	return ret;

}

}
@@ -93,7 +93,7 @@ down_trylock (struct semaphore *sem) 
static inline void

static inline void

up (struct semaphore * sem)

up (struct semaphore * sem)

{

{

	if (atomic_inc_return(&sem->count) <= 0)

	if (ia64_fetchadd(1, &sem->count.counter, rel) <= -1)

		__up(sem);

		__up(sem);

}

}