[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: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-ia64/semaphore.h b/include/asm-ia64/semaphore.h
index bb89062..f483eeb 100644
--- a/include/asm-ia64/semaphore.h
+++ b/include/asm-ia64/semaphore.h
@@ -61,7 +61,7 @@
down (struct semaphore *sem)
{
might_sleep();
- if (atomic_dec_return(&sem->count) < 0)
+ if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
__down(sem);
}
@@ -75,7 +75,7 @@
int ret = 0;
might_sleep();
- if (atomic_dec_return(&sem->count) < 0)
+ if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
ret = __down_interruptible(sem);
return ret;
}
@@ -85,7 +85,7 @@
{
int ret = 0;
- if (atomic_dec_return(&sem->count) < 0)
+ if (ia64_fetchadd(-1, &sem->count.counter, acq) < 1)
ret = __down_trylock(sem);
return ret;
}
@@ -93,7 +93,7 @@
static inline void
up (struct semaphore * sem)
{
- if (atomic_inc_return(&sem->count) <= 0)
+ if (ia64_fetchadd(1, &sem->count.counter, rel) <= -1)
__up(sem);
}