Commit b62526ed authored Jan 14, 2016 by Thomas Gleixner

timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper



Helge reported that a relative timer can return a remaining time larger than
the programmed relative time on parisc and other architectures which have
CONFIG_TIME_LOW_RES set. This happens because we add a jiffie to the resulting
expiry time to prevent short timeouts.

Use the new function hrtimer_expires_remaining_adjusted() to calculate the
remaining time. It takes that extra added time into account for relative
timers.

Reported-and-tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: dhowells@redhat.com
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160114164159.354500742@linutronix.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent 203cbf77

fs/timerfd.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -153,7 +153,7 @@ static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
		if (isalarm(ctx))
		remaining = alarm_expires_remaining(&ctx->t.alarm);
		else
		remaining = hrtimer_expires_remaining(&ctx->t.tmr);
		remaining = hrtimer_expires_remaining_adjusted(&ctx->t.tmr);

		return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
		}

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