diff options
| author | Joshua Hunt <johunt@akamai.com> | 2016-03-17 14:17:23 -0700 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-04-18 08:51:01 -0400 |
| commit | 15207f3ca364563c590ba170ce40c1f90fd78268 (patch) | |
| tree | e7f181244f641f3b3628788f943e5a0cad0e3a31 /kernel | |
| parent | 3ec245e8591a183e276df89cd7f9e7a15645b9da (diff) | |
watchdog: don't run proc_watchdog_update if new value is same as old
[ Upstream commit a1ee1932aa6bea0bb074f5e3ced112664e4637ed ]
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>
Cc: <stable@vger.kernel.org> [4.1.x+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
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 581a68a04c64..f89ea713213f 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -812,6 +812,9 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write, * Update the run state of the lockup detectors. * Restore 'watchdog_enabled' on failure. */ + if (old == new) + goto out; + err = proc_watchdog_update(); if (err) watchdog_enabled = old; @@ -857,7 +860,7 @@ 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; mutex_lock(&watchdog_proc_mutex); @@ -871,6 +874,10 @@ int proc_watchdog_thresh(struct ctl_table *table, int write, * Update the sample period. * Restore 'watchdog_thresh' on failure. */ + new = ACCESS_ONCE(watchdog_thresh); + if (old == new) + goto out; + set_sample_period(); err = proc_watchdog_update(); if (err) |