lkml.org 
[lkml]   [2024]   [Feb]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: timers/core] timekeeping: Fix cross-timestamp interpolation on counter wrap
The following commit has been merged into the timers/core branch of tip:

Commit-ID: 84dccadd3e2a3f1a373826ad71e5ced5e76b0c00
Gitweb: https://git.kernel.org/tip/84dccadd3e2a3f1a373826ad71e5ced5e76b0c00
Author: Peter Hilber <peter.hilber@opensynergy.com>
AuthorDate: Mon, 18 Dec 2023 08:38:39 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 19 Feb 2024 12:18:51 +01:00

timekeeping: Fix cross-timestamp interpolation on counter wrap

cycle_between() decides whether get_device_system_crosststamp() will
interpolate for older counter readings.

cycle_between() yields wrong results for a counter wrap-around where after
< before < test, and for the case after < test < before.

Fix the comparison logic.

Fixes: 2c756feb18d9 ("time: Add history to cross timestamp interface supporting slower devices")
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/r/20231218073849.35294-2-peter.hilber@opensynergy.com

---
kernel/time/timekeeping.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 266d028..8f35455 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1186,7 +1186,7 @@ static bool cycle_between(u64 before, u64 test, u64 after)
{
if (test > before && test < after)
return true;
- if (test < before && before > after)
+ if (before > after && (test > before || test < after))
return true;
return false;
}
\
 
 \ /
  Last update: 2024-05-27 15:10    [W:0.186 / U:0.356 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site