6.5-stable review patch. If anyone has any objections, please let me know.
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From: Paul E. McKenney paulmck@kernel.org
[ Upstream commit e40806e9bcf8aaa86dbf0d484e7cf3cfa09cb86c ]
The nanosecond-to-millisecond skew computation uses unsigned arithmetic, which produces user-unfriendly large positive numbers for negative skews. Therefore, use signed arithmetic for this computation in order to preserve the negativity.
Reported-by: Chris Bainbridge chris.bainbridge@gmail.com Reported-by: Feng Tang feng.tang@intel.com Fixes: dd029269947a ("clocksource: Improve "skew is too large" messages") Reviewed-by: Feng Tang feng.tang@intel.com Tested-by: Chris Bainbridge chris.bainbridge@gmail.com Signed-off-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/time/clocksource.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 88cbc1181b239..c108ed8a9804a 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -473,8 +473,8 @@ static void clocksource_watchdog(struct timer_list *unused) /* Check the deviation from the watchdog clocksource. */ md = cs->uncertainty_margin + watchdog->uncertainty_margin; if (abs(cs_nsec - wd_nsec) > md) { - u64 cs_wd_msec; - u64 wd_msec; + s64 cs_wd_msec; + s64 wd_msec; u32 wd_rem;
pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", @@ -483,8 +483,8 @@ static void clocksource_watchdog(struct timer_list *unused) watchdog->name, wd_nsec, wdnow, wdlast, watchdog->mask); pr_warn(" '%s' cs_nsec: %lld cs_now: %llx cs_last: %llx mask: %llx\n", cs->name, cs_nsec, csnow, cslast, cs->mask); - cs_wd_msec = div_u64_rem(cs_nsec - wd_nsec, 1000U * 1000U, &wd_rem); - wd_msec = div_u64_rem(wd_nsec, 1000U * 1000U, &wd_rem); + cs_wd_msec = div_s64_rem(cs_nsec - wd_nsec, 1000 * 1000, &wd_rem); + wd_msec = div_s64_rem(wd_nsec, 1000 * 1000, &wd_rem); pr_warn(" Clocksource '%s' skewed %lld ns (%lld ms) over watchdog '%s' interval of %lld ns (%lld ms)\n", cs->name, cs_nsec - wd_nsec, cs_wd_msec, watchdog->name, wd_nsec, wd_msec); if (curr_clocksource == cs)