This is a note to let you know that I have just added a patch titled
timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper
to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue
This patch is scheduled to be released in version 4.2.8-ckt4.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
---8<------------------------------------------------------------
From 29fa3c106967ccf964baa80b84eae2e4c4690d5d Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Thu, 14 Jan 2016 16:54:46 +0000
Subject: timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper
commit b62526ed11a1fe3861ab98d40b7fdab8981d788a upstream.
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@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: linux-m68k@xxxxxxxxxxxxxxxxxxxx
Cc: dhowells@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20160114164159.354500742@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
fs/timerfd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/timerfd.c b/fs/timerfd.c
index b94fa6c..053818d 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -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;
}
--
1.9.1
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