The patch titled
Subject: kernel/watchdog.c: remove {get|put}_online_cpus() from watchdog_{park|unpark}_threads()
has been added to the -mm tree. Its filename is
watchdog-remove-getput_online_cpus-from-watchdog_parkunpark_threads.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/watchdog-remove-getput_online_cpus-from-watchdog_parkunpark_threads.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/watchdog-remove-getput_online_cpus-from-watchdog_parkunpark_threads.patch
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------------------------------------------------------
From: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Subject: kernel/watchdog.c: remove {get|put}_online_cpus() from watchdog_{park|unpark}_threads()
watchdog_{park|unpark}_threads() are now called in code paths that protect
themselves against CPU hotplug, so {get|put}_online_cpus() calls are
redundant and can be removed.
Signed-off-by: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Aaron Tomlin <atomlin@xxxxxxxxxx>
Cc: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/watchdog.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff -puN kernel/watchdog.c~watchdog-remove-getput_online_cpus-from-watchdog_parkunpark_threads kernel/watchdog.c
--- a/kernel/watchdog.c~watchdog-remove-getput_online_cpus-from-watchdog_parkunpark_threads
+++ a/kernel/watchdog.c
@@ -683,33 +683,35 @@ static struct smp_hotplug_thread watchdo
* be parked and the watchdog threads of other CPUs can still be runnable.
* Callers are expected to handle this special condition as appropriate in
* their context.
+ *
+ * This function may only be called in a context that is protected against
+ * races with CPU hotplug - for example, via get_online_cpus().
*/
static int watchdog_park_threads(void)
{
int cpu, ret = 0;
- get_online_cpus();
for_each_watchdog_cpu(cpu) {
ret = kthread_park(per_cpu(softlockup_watchdog, cpu));
if (ret)
break;
}
- put_online_cpus();
return ret;
}
/*
* unpark all watchdog threads that are specified in 'watchdog_cpumask'
+ *
+ * This function may only be called in a context that is protected against
+ * races with CPU hotplug - for example, via get_online_cpus().
*/
static void watchdog_unpark_threads(void)
{
int cpu;
- get_online_cpus();
for_each_watchdog_cpu(cpu)
kthread_unpark(per_cpu(softlockup_watchdog, cpu));
- put_online_cpus();
}
/*
_
Patches currently in -mm which might be from uobergfe@xxxxxxxxxx are
watchdog-fix-error-handling-in-proc_watchdog_thresh.patch
watchdog-move-watchdog_disable_all_cpus-outside-of-ifdef.patch
watchdog-implement-error-handling-in-update_watchdog_all_cpus-and-callers.patch
watchdog-implement-error-handling-in-lockup_detector_suspend.patch
watchdog-do-not-unpark-threads-in-watchdog_park_threads-on-error.patch
watchdog-avoid-race-between-lockup-detector-suspend-resume-and-cpu-hotplug.patch
watchdog-avoid-races-between-proc-handlers-and-cpu-hotplug.patch
watchdog-remove-getput_online_cpus-from-watchdog_parkunpark_threads.patch
watchdog-fix-race-between-proc_watchdog_thresh-and-watchdog_timer_fn.patch
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