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Correct a locking error in apause: It should always hold

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the simple lock when it returns.

Also, eliminate spinning on a uniprocessor.  It's pointless.

Submitted by:	bde,
		Assar Westerlund <assar@sics.se>
This commit is contained in:
Alan Cox 1999-11-11 03:02:03 +00:00
parent 0c38fb0340
commit 99c9d3490b
1 changed files with 16 additions and 14 deletions
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30
sys/kern/kern_lock.c
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@ -103,23 +103,25 @@ shareunlock(struct lock *lkp, int decr) {
* optimization troubles.
*/
static int
apause(struct lock *lkp, int flags) {
int lock_wait;
lock_wait = LOCK_WAIT_TIME;
for (; lock_wait > 0; lock_wait--) {
int i;
apause(struct lock *lkp, int flags)
{
#ifdef SMP
int i, lock_wait;
#endif
if ((lkp->lk_flags & flags) == 0)
return 0;
#ifdef SMP
for (lock_wait = LOCK_WAIT_TIME; lock_wait > 0; lock_wait--) {
simple_unlock(&lkp->lk_interlock);
for (i = LOCK_SAMPLE_WAIT; i > 0; i--)
if ((lkp->lk_flags & flags) == 0)
break;
simple_lock(&lkp->lk_interlock);
if ((lkp->lk_flags & flags) == 0)
return 0;
simple_unlock(&lkp->lk_interlock);
for (i = LOCK_SAMPLE_WAIT; i > 0; i--) {
if ((lkp->lk_flags & flags) == 0) {
simple_lock(&lkp->lk_interlock);
if ((lkp->lk_flags & flags) == 0)
return 0;
break;
}
}
}
#endif
return 1;
}