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When releasing a lockmgr held in shared way we need to use a write memory

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barrier in order to avoid, on architectures which doesn't have strong
ordered writes, CPU instructions reordering.

Diagnosed by:	fabio
This commit is contained in:
Attilio Rao 2009-10-03 15:02:55 +00:00
parent bba017d6a0
commit 7f9f80ce03
1 changed files with 3 additions and 3 deletions
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6
sys/kern/kern_lock.c
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@ -241,7 +241,7 @@ wakeupshlk(struct lock *lk, const char *file, int line)
* and return.
*/
if (LK_SHARERS(x) > 1) {
if (atomic_cmpset_ptr(&lk->lk_lock, x,
if (atomic_cmpset_rel_ptr(&lk->lk_lock, x,
x - LK_ONE_SHARER))
break;
continue;
@ -254,7 +254,7 @@ wakeupshlk(struct lock *lk, const char *file, int line)
if ((x & LK_ALL_WAITERS) == 0) {
MPASS((x & ~LK_EXCLUSIVE_SPINNERS) ==
LK_SHARERS_LOCK(1));
if (atomic_cmpset_ptr(&lk->lk_lock, x, LK_UNLOCKED))
if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, LK_UNLOCKED))
break;
continue;
}
@ -280,7 +280,7 @@ wakeupshlk(struct lock *lk, const char *file, int line)
queue = SQ_SHARED_QUEUE;
}
if (!atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x,
if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x,
v)) {
sleepq_release(&lk->lock_object);
continue;