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Two small fixes for the time(r) subsystem:

Browse Source 
- Handle a subtle race between the clocksource watchdog and a concurrent
     clocksource watchdog stop/start sequence correctly to prevent a timer
     double add bug.
 
   - Fix the file path for the core time namespace file.
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Merge tag 'timers-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fixes from Thomas Gleixner:
 "Two small fixes for the time(r) subsystem:

   - Handle a subtle race between the clocksource watchdog and a
     concurrent clocksource watchdog stop/start sequence correctly to
     prevent a timer double add bug.

   - Fix the file path for the core time namespace file"

* tag 'timers-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource: Prevent double add_timer_on() for watchdog_timer
  MAINTAINERS: Correct path to time namespace source file
This commit is contained in:
Linus Torvalds 2020-02-09 12:00:12 -08:00
commit 2fbc23c738
2 changed files with 10 additions and 3 deletions
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2
MAINTAINERS
View File

@ -13360,7 +13360,7 @@ S: Maintained
F: fs/timerfd.c
F: include/linux/timer*
F: include/linux/time_namespace.h
F: kernel/time_namespace.c
F: kernel/time/namespace.c
F: kernel/time/*timer*
POWER MANAGEMENT CORE

11
kernel/time/clocksource.c
View File

@ -293,8 +293,15 @@ static void clocksource_watchdog(struct timer_list *unused)
next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
if (next_cpu >= nr_cpu_ids)
next_cpu = cpumask_first(cpu_online_mask);
watchdog_timer.expires += WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer, next_cpu);
/*
* Arm timer if not already pending: could race with concurrent
* pair clocksource_stop_watchdog() clocksource_start_watchdog().
*/
if (!timer_pending(&watchdog_timer)) {
watchdog_timer.expires += WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer, next_cpu);
}
out:
spin_unlock(&watchdog_lock);
}