From: Darren Hart Date: Thu, 12 Mar 2009 07:56:06 +0000 (-0700) Subject: futex: unlock before returning -EFAULT X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=e8f6386c01a5699c115bdad10271a24076364c97;p=deliverable%2Flinux.git futex: unlock before returning -EFAULT Impact: rt-mutex failure case fix futex_lock_pi can potentially return -EFAULT with the rt_mutex held. This seems like the wrong thing to do as userspace should assume -EFAULT means the lock was not taken. Even if it could figure this out, we'd be leaving the pi_state->owner in an inconsistent state. This patch unlocks the rt_mutex prior to returning -EFAULT to userspace. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart Acked-by: Peter Zijlstra Cc: Rusty Russell LKML-Reference: <20090312075606.9856.88729.stgit@Aeon> Signed-off-by: Ingo Molnar --- diff --git a/kernel/futex.c b/kernel/futex.c index 6579912ee70c..c980a556f82c 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1567,6 +1567,13 @@ retry_locked: } } + /* + * If fixup_pi_state_owner() faulted and was unable to handle the + * fault, unlock it and return the fault to userspace. + */ + if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) + rt_mutex_unlock(&q.pi_state->pi_mutex); + /* Unqueue and drop the lock */ unqueue_me_pi(&q);