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Add a missing lockstat:::sx-downgrade probe.

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We were returning without firing the probe when the lock had no shared
waiters.

MFC after:	1 week
This commit is contained in:
markj 2017-11-24 19:02:06 +00:00
parent c317aee78b
commit e32cd825f4
1 changed files with 6 additions and 7 deletions
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13
sys/kern/kern_sx.c
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@ -480,10 +480,8 @@ sx_downgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF)
x = sx->sx_lock;
if (!(x & SX_LOCK_SHARED_WAITERS) &&
atomic_cmpset_rel_ptr(&sx->sx_lock, x, SX_SHARERS_LOCK(1) |
(x & SX_LOCK_EXCLUSIVE_WAITERS))) {
LOCK_LOG_LOCK("XDOWNGRADE", &sx->lock_object, 0, 0, file, line);
return;
}
(x & SX_LOCK_EXCLUSIVE_WAITERS)))
goto out;
/*
* Lock the sleep queue so we can read the waiters bits
@ -504,11 +502,12 @@ sx_downgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF)
0, SQ_SHARED_QUEUE);
sleepq_release(&sx->lock_object);
LOCK_LOG_LOCK("XDOWNGRADE", &sx->lock_object, 0, 0, file, line);
LOCKSTAT_RECORD0(sx__downgrade, sx);
if (wakeup_swapper)
kick_proc0();
out:
LOCK_LOG_LOCK("XDOWNGRADE", &sx->lock_object, 0, 0, file, line);
LOCKSTAT_RECORD0(sx__downgrade, sx);
}
void