diff options
| author | Ulrich Obergfell | 2014-10-13 15:55:35 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2014-10-14 02:18:27 +0200 |
| commit | 6e7458a6f074c71e74cda31c483114e65ea0f570 (patch) | |
| tree | d942b6b9ec308d66f64649b94d088b02bf2e6309 /include/linux | |
| parent | 8a1db92830d0a71e1429725992eb91470214c820 (diff) | |
kernel/watchdog.c: control hard lockup detection default
In some cases we don't want hard lockup detection enabled by default.
An example is when running as a guest. Introduce
watchdog_enable_hardlockup_detector(bool)
allowing those cases to disable hard lockup detection. This must be
executed early by the boot processor from e.g. smp_prepare_boot_cpu, in
order to allow kernel command line arguments to override it, as well as
to avoid hard lockup detection being enabled before we've had a chance
to indicate that it's unwanted. In summary,
initial boot: default=enabled
smp_prepare_boot_cpu
watchdog_enable_hardlockup_detector(false): default=disabled
cmdline has 'nmi_watchdog=1': default=enabled
The running kernel still has the ability to enable/disable at any time
with /proc/sys/kernel/nmi_watchdog us usual. However even when the
default has been overridden /proc/sys/kernel/nmi_watchdog will initially
show '1'. To truly turn it on one must disable/enable it, i.e.
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /proc/sys/kernel/nmi_watchdog
This patch will be immediately useful for KVM with the next patch of this
series. Other hypervisor guest types may find it useful as well.
[akpm@linux-foundation.org: fix build]
[dzickus@redhat.com: fix compile issues on sparc]
Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/nmi.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 1d2a6ab6b8bb..9b2022ab4d85 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -24,6 +24,19 @@ static inline void touch_nmi_watchdog(void) } #endif +#if defined(CONFIG_HARDLOCKUP_DETECTOR) +extern void watchdog_enable_hardlockup_detector(bool val); +extern bool watchdog_hardlockup_detector_is_enabled(void); +#else +static inline void watchdog_enable_hardlockup_detector(bool val) +{ +} +static inline bool watchdog_hardlockup_detector_is_enabled(void) +{ + return true; +} +#endif + /* * Create trigger_all_cpu_backtrace() out of the arch-provided * base function. Return whether such support was available, |