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From 45e80542dc4abd6e4267c25ce13925bd64aed41d Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 25 Jan 2012 11:08:40 +0100
Subject: [PATCH 120/254] timer-fd: Prevent live lock
If hrtimer_try_to_cancel() requires a retry, then depending on the
priority setting te retry loop might prevent timer callback completion
on RT. Prevent that by waiting for completion on RT, no change for a
non RT kernel.
Reported-by: Sankara Muthukrishnan <sankara.m@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
---
fs/timerfd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/timerfd.c b/fs/timerfd.c
index dffeb37..57f0e4e 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -313,7 +313,7 @@ SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
break;
spin_unlock_irq(&ctx->wqh.lock);
- cpu_relax();
+ hrtimer_wait_for_timer(&ctx->tmr);
}
/*
--
1.7.10.4
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