Application threads calling futex_wait_requeue_pi run in an infinite loop
in the kernel if the futex value changes during the call. The following
patch fixes the problem.
Signed-off-by: Dinakar Guniguntala <dino@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Darren Hart <dvhltc@xxxxxxxxxx>
---
kernel/futex.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
Index: linux-2.6.31.4-rt14-lbf-f1/kernel/futex.c
===================================================================
--- linux-2.6.31.4-rt14-lbf-f1.orig/kernel/futex.c
+++ linux-2.6.31.4-rt14-lbf-f1/kernel/futex.c
@@ -2188,6 +2188,12 @@ retry:
spin_lock(&hb->lock);
ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
spin_unlock(&hb->lock);
+ if (ret == -EAGAIN) {
+ /* Retry on spurious wakeup */
+ put_futex_key(fshared, &q.key);
+ put_futex_key(fshared, &key2);
+ goto retry;
+ }
if (ret)
goto out_put_keys;
@@ -2264,9 +2270,6 @@ out_put_keys:
out_key2:
put_futex_key(fshared, &key2);
- /* Spurious wakeup ? */
- if (ret == -EAGAIN)
- goto retry;
out:
if (to) {
hrtimer_cancel(&to->timer);
--
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