From: Nicolai Hähnle <[email protected]> Help catch cases where mutex_lock is used directly on w/w mutexes, which otherwise result in the w/w tasks reading uninitialized data.
Cc: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Maarten Lankhorst <[email protected]> Cc: Daniel Vetter <[email protected]> Cc: Chris Wilson <[email protected]> Cc: [email protected] Signed-off-by: Nicolai Hähnle <[email protected]> --- include/linux/poison.h | 1 + kernel/locking/mutex.c | 4 ++++ 2 files changed, 5 insertions(+) diff --git a/include/linux/poison.h b/include/linux/poison.h index 51334ed..a395403 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -80,6 +80,7 @@ /********** kernel/mutexes **********/ #define MUTEX_DEBUG_INIT 0x11 #define MUTEX_DEBUG_FREE 0x22 +#define MUTEX_POISON_WW_CTX ((void *) 0x500 + POISON_POINTER_DELTA) /********** lib/flex_array.c **********/ #define FLEX_ARRAY_FREE 0x6c /* for use-after-free poisoning */ diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 1e4da21..ee84007 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -783,6 +783,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, if (!use_ww_ctx) { /* add waiting tasks to the end of the waitqueue (FIFO): */ list_add_tail(&waiter.list, &lock->wait_list); + +#ifdef CONFIG_DEBUG_MUTEXES + waiter.ww_ctx = MUTEX_POISON_WW_CTX; +#endif } else { /* Add in stamp order, waking up waiters that must back off. */ ret = __ww_mutex_add_waiter(&waiter, lock, ww_ctx); -- 2.7.4
