diff options
| author | Joshua Hunt <johunt@akamai.com> | 2016-03-17 14:17:23 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-12 09:08:54 -0700 |
| commit | 5f4a82d5e3492c26fb0263ca7f007180612e8b54 (patch) | |
| tree | f7f466ba519f41a5c76dd3dc6948e79412e5d969 /kernel | |
| parent | ee52f62c636c0c151ea92ffbf5ef940be51b0d22 (diff) | |
watchdog: don't run proc_watchdog_update if new value is same as old
commit a1ee1932aa6bea0bb074f5e3ced112664e4637ed upstream.
While working on a script to restore all sysctl params before a series of
tests I found that writing any value into the
/proc/sys/kernel/{nmi_watchdog,soft_watchdog,watchdog,watchdog_thresh}
causes them to call proc_watchdog_update().
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
There doesn't appear to be a reason for doing this work every time a write
occurs, so only do it when the values change.
Signed-off-by: Josh Hunt <johunt@akamai.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/watchdog.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 18f34cf75f74..198137b1cadc 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -907,6 +907,9 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write, * both lockup detectors are disabled if proc_watchdog_update() * returns an error. */ + if (old == new) + goto out; + err = proc_watchdog_update(); } out: @@ -951,7 +954,7 @@ int proc_soft_watchdog(struct ctl_table *table, int write, int proc_watchdog_thresh(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { - int err, old; + int err, old, new; get_online_cpus(); mutex_lock(&watchdog_proc_mutex); @@ -971,6 +974,10 @@ int proc_watchdog_thresh(struct ctl_table *table, int write, /* * Update the sample period. Restore on failure. */ + new = ACCESS_ONCE(watchdog_thresh); + if (old == new) + goto out; + set_sample_period(); err = proc_watchdog_update(); if (err) { |