Author: markj
Date: Fri Nov 24 19:02:06 2017
New Revision: 326175
URL: https://svnweb.freebsd.org/changeset/base/326175
Log:
Add a missing lockstat:::sx-downgrade probe.
We were returning without firing the probe when the lock had no shared
waiters.
MFC after: 1 week
Modified:
head/sys/kern/kern_sx.c
Modified: head/sys/kern/kern_sx.c
==============================================================================
--- head/sys/kern/kern_sx.c Fri Nov 24 19:01:14 2017 (r326174)
+++ head/sys/kern/kern_sx.c Fri Nov 24 19:02:06 2017 (r326175)
@@ -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
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