[PATCH V2] futex: set FLAGS_HAS_TIMEOUT during demux for FUTEX_WAIT

[Darren Hart <dvhart@linux.intel.com>]

The FLAGS_HAS_TIMEOUT flag was not getting set, causing the restart_block to
restart futex_wait() without a timeout after a signal.

Commit b41277dc7a18ee332d in 2.6.38 introduced the regression by accidentally
removing the the FLAGS_HAS_TIMEOUT assignment from futex_wait() during the setup
of the restart block. It makes more sense to set the flag earlier during
do_futex() where the other flags are set, although futex_wait is the only user
of FLAGS_HAS_TIMEOUT as it is the only op using a relative timeout (an
unfortunately preexisting condition).

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=32922

V2: Added references to commit message.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Reported-by: Tim Smith <tsmith201104@yahoo.com>
Reported-by: Torsten Hilbrich <torsten.hilbrich@secunet.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: John Kacur <jkacur@redhat.com>
---
 kernel/futex.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index bda4157..6eac6b6 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2589,6 +2589,9 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 			return -ENOSYS;
 	}
 
+	if (timeout)
+		flags |= FLAGS_HAS_TIMEOUT;
+
 	switch (cmd) {
 	case FUTEX_WAIT:
 		val3 = FUTEX_BITSET_MATCH_ANY;
-- 
1.7.1