This is a note to let you know that I've just added the patch titled
timer: Fix wheel index calculation on last level
to the 5.7-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:
timer-fix-wheel-index-calculation-on-last-level.patch
and it can be found in the queue-5.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e2a71bdea81690b6ef11f4368261ec6f5b6891aa Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <frederic@xxxxxxxxxx>
Date: Fri, 17 Jul 2020 16:05:40 +0200
Subject: timer: Fix wheel index calculation on last level
From: Frederic Weisbecker <frederic@xxxxxxxxxx>
commit e2a71bdea81690b6ef11f4368261ec6f5b6891aa upstream.
When an expiration delta falls into the last level of the wheel, that delta
has be compared against the maximum possible delay and reduced to fit in if
necessary.
However instead of comparing the delta against the maximum, the code
compares the actual expiry against the maximum. Then instead of fixing the
delta to fit in, it sets the maximum delta as the expiry value.
This can result in various undesired outcomes, the worst possible one
being a timer expiring 15 days ahead to fire immediately.
Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel")
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20200717140551.29076-2-frederic@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/timer.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -522,8 +522,8 @@ static int calc_wheel_index(unsigned lon
* Force expire obscene large timeouts to expire at the
* capacity limit of the wheel.
*/
- if (expires >= WHEEL_TIMEOUT_CUTOFF)
- expires = WHEEL_TIMEOUT_MAX;
+ if (delta >= WHEEL_TIMEOUT_CUTOFF)
+ expires = clk + WHEEL_TIMEOUT_MAX;
idx = calc_index(expires, LVL_DEPTH - 1);
}
Patches currently in stable-queue which might be from frederic@xxxxxxxxxx are
queue-5.7/timer-fix-wheel-index-calculation-on-last-level.patch
queue-5.7/timer-prevent-base-clk-from-moving-backward.patch
