summaryrefslogtreecommitdiffstats
path: root/kernel/locking/mutex.c
diff options
context:
space:
mode:
authorPeter Zijlstra <peterz@infradead.org>2014-03-12 13:24:42 +0100
committerIngo Molnar <mingo@kernel.org>2014-03-12 13:49:47 +0100
commit6f008e72cd111a119b5d8de8c5438d892aae99eb (patch)
treed00f4254e5ae2a3def0a70ab15d7a8794fc6d6a1 /kernel/locking/mutex.c
parent34c6bc2c919a55e5ad4e698510a2f35ee13ab900 (diff)
downloadop-kernel-dev-6f008e72cd111a119b5d8de8c5438d892aae99eb.zip
op-kernel-dev-6f008e72cd111a119b5d8de8c5438d892aae99eb.tar.gz
locking/mutex: Fix debug checks
OK, so commit: 1d8fe7dc8078 ("locking/mutexes: Unlock the mutex without the wait_lock") generates this boot warning when CONFIG_DEBUG_MUTEXES=y: WARNING: CPU: 0 PID: 139 at /usr/src/linux-2.6/kernel/locking/mutex-debug.c:82 debug_mutex_unlock+0x155/0x180() DEBUG_LOCKS_WARN_ON(lock->owner != current) And that makes sense, because as soon as we release the lock a new owner can come in... One would think that !__mutex_slowpath_needs_to_unlock() implementations suffer the same, but for DEBUG we fall back to mutex-null.h which has an unconditional 1 for that. The mutex debug code requires the mutex to be unlocked after doing the debug checks, otherwise it can find inconsistent state. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: jason.low2@hp.com Link: http://lkml.kernel.org/r/20140312122442.GB27965@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking/mutex.c')
-rw-r--r--kernel/locking/mutex.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 02c61a9..14fe72c 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -34,6 +34,13 @@
#ifdef CONFIG_DEBUG_MUTEXES
# include "mutex-debug.h"
# include <asm-generic/mutex-null.h>
+/*
+ * Must be 0 for the debug case so we do not do the unlock outside of the
+ * wait_lock region. debug_mutex_unlock() will do the actual unlock in this
+ * case.
+ */
+# undef __mutex_slowpath_needs_to_unlock
+# define __mutex_slowpath_needs_to_unlock() 0
#else
# include "mutex.h"
# include <asm/mutex.h>
OpenPOWER on IntegriCloud