Messages in this thread Patch in this message | | | From | Darren Hart <> | Subject | [PATCH 5/6] futex: unlock before returning -EFAULT | Date | Thu, 12 Mar 2009 00:56:06 -0700 |
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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 <dvhltc@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Rusty Russell <rusty@rustcorp.com.au> ---
kernel/futex.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c index 6579912..c980a55 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);
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