From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Wed, 3 Nov 2010 22:56:53 +0000 (-0700)
Subject: Clear owner after dropping mutex
X-Git-Tag: zfs-0.8.0-rc1~152^2~526
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8294c69bb759d2a4dc2e73f164cb37c297722ada;p=zfs

Clear owner after dropping mutex

It's important to clear mp->owner after calling mutex_unlock()
because when CONFIG_DEBUG_MUTEXES is defined the mutex owner
is verified in mutex_unlock().  If we set it to NULL this check
fails and the lockdep support is immediately disabled.
---

diff --git a/include/sys/mutex.h b/include/sys/mutex.h
index 97f49cb2a..1a8b25813 100644
--- a/include/sys/mutex.h
+++ b/include/sys/mutex.h
@@ -81,8 +81,8 @@ mutex_owned(kmutex_t *mp)
 #ifdef CONFIG_DEBUG_MUTEXES
 # define mutex_exit(mp)                                                 \
 ({                                                                      \
-         (mp)->owner = NULL;                                            \
-	 mutex_unlock(mp);                                              \
+        mutex_unlock(mp);                                               \
+        (mp)->owner = NULL;                                             \
 })
 #else
 # define mutex_exit(mp)                 mutex_unlock(mp)