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authorDarren Hart <dvhltc@us.ibm.com>2009-03-12 00:56:06 -0700
committerIngo Molnar <mingo@elte.hu>2009-03-12 11:20:57 +0100
commite8f6386c01a5699c115bdad10271a24076364c97 (patch)
tree7375a9b8961c0e0fd8e25176c7912375aaaa4d1e /kernel
parent16f4993f4e9860715918efd4eeac928f8de1218b (diff)
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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 <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312075606.9856.88729.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/futex.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 6579912ee70..c980a556f82 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);