diff options
| author |   Peter Zijlstra <peterz@infradead.org> | 2014-03-12 13:24:42 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2014-03-12 13:49:47 +0100 |
| commit | 6f008e72cd111a119b5d8de8c5438d892aae99eb (patch) | |
| tree | d00f4254e5ae2a3def0a70ab15d7a8794fc6d6a1 /kernel/locking/mutex.c | |
| parent | locking/mutexes: Add extra reschedule point (diff) | |
| download | linux-dev-6f008e72cd111a119b5d8de8c5438d892aae99eb.tar.xz linux-dev-6f008e72cd111a119b5d8de8c5438d892aae99eb.zip | |
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 '')
| -rw-r--r-- | kernel/locking/mutex.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 02c61a9c8906..14fe72cc8ce7 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> |