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-rw-r--r--fs/eventpoll.c25
1 files changed, 16 insertions, 9 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 10b81e69db74..935c66c809ba 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1817,23 +1817,30 @@ fetch_events:
}
write_unlock_irq(&ep->lock);
- if (eavail || res)
- break;
+ if (!eavail && !res)
+ timed_out = !schedule_hrtimeout_range(to, slack,
+ HRTIMER_MODE_ABS);
- if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) {
- timed_out = 1;
- break;
- }
-
- /* We were woken up, thus go and try to harvest some events */
+ /*
+ * We were woken up, thus go and try to harvest some events.
+ * If timed out and still on the wait queue, recheck eavail
+ * carefully under lock, below.
+ */
eavail = 1;
-
} while (0);
__set_current_state(TASK_RUNNING);
if (!list_empty_careful(&wait.entry)) {
write_lock_irq(&ep->lock);
+ /*
+ * If the thread timed out and is not on the wait queue, it
+ * means that the thread was woken up after its timeout expired
+ * before it could reacquire the lock. Thus, when wait.entry is
+ * empty, it needs to harvest events.
+ */
+ if (timed_out)
+ eavail = list_empty(&wait.entry);
__remove_wait_queue(&ep->wq, &wait);
write_unlock_irq(&ep->lock);
}