[PATCH v2 1/2] Fix robust mutex daedlock [BZ #20263]

[Jiyoung Yun]

In Linux/ARM environment, a robust mutex can't catch the timeout result
when it is already owned by other thread and requests to try lock with
a specific time value(pthread_mutex_timedlock). The futex already returns
the ETIMEDOUT result but there is no check the return value and it makes
a deadlock.

* nptl/lowlevelrobustlock.c: Implement ETIMEDOUT logic.
---
 ChangeLog                 | 5 +++++
 nptl/lowlevelrobustlock.c | 9 +++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 3da2eca..97461f6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-06-28  Jiyoung Yun  <t2wish@gmail.com>
+
+	[BZ #20263]
+	* nptl/lowlevelrobustlock.c: Implement ETIMEDOUT logic.
+
 2016-06-28  Richard Henderson  <rth@redhat.com>
 
 	* elf/elf.h (EM_BPF): New.
diff --git a/nptl/lowlevelrobustlock.c b/nptl/lowlevelrobustlock.c
index 3b988b2..e5d3758 100644
--- a/nptl/lowlevelrobustlock.c
+++ b/nptl/lowlevelrobustlock.c
@@ -113,15 +113,20 @@ __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime,
 	  && atomic_compare_and_exchange_bool_acq (futex, newval, oldval))
 	continue;
 
+      int err;
       /* If *futex == 2, wait until woken or timeout.  */
 #if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
      || !defined lll_futex_timed_wait_bitset)
-      lll_futex_timed_wait (futex, newval, &rt, private);
+      err = lll_futex_timed_wait (futex, newval, &rt, private);
 #else
-      lll_futex_timed_wait_bitset (futex, newval, abstime,
+      err = lll_futex_timed_wait_bitset (futex, newval, abstime,
 				   FUTEX_CLOCK_REALTIME, private);
 #endif
 
+      /* the futex call time out */
+      if (err == -ETIMEDOUT)
+         return -err;
+
     try:
       ;
     }
-- 
1.9.1