This is a note to let you know that I've just added the patch titled
tick-sched: Don't call update_wall_time() when delta is lesser than tick_period
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tick-sched-don-t-call-update_wall_time-when-delta-is-lesser-than-tick_period.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 03e6bdc5c4d0fc166bfd5d3cf749a5a0c1b5b1bd Mon Sep 17 00:00:00 2001
From: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Date: Tue, 15 Apr 2014 10:54:40 +0530
Subject: tick-sched: Don't call update_wall_time() when delta is lesser than tick_period
From: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
commit 03e6bdc5c4d0fc166bfd5d3cf749a5a0c1b5b1bd upstream.
In tick_do_update_jiffies64() we are processing ticks only if delta is
greater than tick_period. This is what we are supposed to do here and
it broke a bit with this patch:
commit 47a1b796 (tick/timekeeping: Call update_wall_time outside the
jiffies lock)
With above patch, we might end up calling update_wall_time() even if
delta is found to be smaller that tick_period. Fix this by returning
when the delta is less than tick period.
[ tglx: Made it a 3 liner and massaged changelog ]
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Cc: linaro-kernel@xxxxxxxxxxxxxxxx
Cc: fweisbec@xxxxxxxxx
Cc: Arvind.Chauhan@xxxxxxx
Cc: linaro-networking@xxxxxxxxxx
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/80afb18a494b0bd9710975bcc4de134ae323c74f.1397537987.git.viresh.kumar@xxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/tick-sched.c | 3 +++
1 file changed, 3 insertions(+)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -84,6 +84,9 @@ static void tick_do_update_jiffies64(kti
/* Keep the tick_next_period variable up to date */
tick_next_period = ktime_add(last_jiffies_update, tick_period);
+ } else {
+ write_sequnlock(&jiffies_lock);
+ return;
}
write_sequnlock(&jiffies_lock);
update_wall_time();
Patches currently in stable-queue which might be from viresh.kumar@xxxxxxxxxx are
queue-3.14/tick-common-fix-wrong-check-in-tick_check_replacement.patch
queue-3.14/tick-sched-check-tick_nohz_enabled-in-tick_nohz_switch_to_nohz.patch
queue-3.14/tick-sched-don-t-call-update_wall_time-when-delta-is-lesser-than-tick_period.patch
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