linux-toradex.git/kernel/watchdog.c, branch v3.0-rc3

watchdog: Fix non-standard prototype of get_softlockup_thresh()

2011-05-24T03:53:39+00:00

This build warning slipped through:

  kernel/watchdog.c:102: warning: function declaration isn't a prototype

As reported by Stephen Rothwell.

Also address an unused variable warning that GCC 4.6.0 reports:
we cannot do anything about failed watchdog ops during CPU hotplug
(it's not serious enough to return an error from the notifier),
so ignore them.

Reported-by: Stephen Rothwell 
Cc: Mandeep Singh Baines 
Cc: Marcin Slusarz 
Cc: Don Zickus 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/20110524134129.8da27016.sfr@canb.auug.org.au
Signed-off-by: Ingo Molnar 
LKML-Reference: <20110517071642.GF22305@elte.hu>

watchdog: Change the default timeout and configure nmi watchdog period based on watchdog_thresh

2011-05-23T09:58:59+00:00

Before the conversion of the NMI watchdog to perf event, the
watchdog timeout was 5 seconds. Now it is 60 seconds. For my
particular application, netbooks, 5 seconds was a better
timeout. With a short timeout, we catch faults earlier and are
able to send back a panic. With a 60 second timeout, the user is
unlikely to wait and will instead hit the power button, causing
us to lose the panic info.

This change configures the NMI period to watchdog_thresh and
sets the softlockup_thresh to watchdog_thresh * 2. In addition,
watchdog_thresh was reduced to 10 seconds as suggested by Ingo
Molnar.

Signed-off-by: Mandeep Singh Baines 
Cc: Marcin Slusarz 
Cc: Don Zickus 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/1306127423-3347-4-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar 
LKML-Reference: <20110517071642.GF22305@elte.hu>

watchdog: Disable watchdog when thresh is zero

2011-05-23T09:58:59+00:00

This restores the previous behavior of softlock_thresh.

Currently, setting watchdog_thresh to zero causes the watchdog
kthreads to consume a lot of CPU.

In addition, the logic of proc_dowatchdog_thresh and
proc_dowatchdog_enabled has been factored into proc_dowatchdog.

Signed-off-by: Mandeep Singh Baines 
Cc: Marcin Slusarz 
Cc: Don Zickus 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/1306127423-3347-3-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar 
LKML-Reference: <20110517071018.GE22305@elte.hu>

watchdog: Only disable/enable watchdog if neccessary

2011-05-23T09:58:58+00:00

Don't take any action on an unsuccessful write to /proc.

Signed-off-by: Mandeep Singh Baines 
Cc: Marcin Slusarz 
Cc: Don Zickus 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/1306127423-3347-2-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar

watchdog: Fix rounding bug in get_sample_period()

2011-05-23T09:58:58+00:00

In get_sample_period(), softlockup_thresh is integer divided by
5 before the multiplication by NSEC_PER_SEC. This results in
softlockup_thresh being rounded down to the nearest integer
multiple of 5.

For example, a softlockup_thresh of 4 rounds down to 0.

Signed-off-by: Mandeep Singh Baines 
Cc: Marcin Slusarz 
Cc: Don Zickus 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/1306127423-3347-1-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar

kernel/watchdog.c: disable nmi perf event in the error path of enabling watchdog

2011-04-28T18:28:21+00:00

In corner cases where softlockup watchdog is not setup successfully, the
relevant nmi perf event for hardlockup watchdog could be disabled, then
the status of the underlying hardware remains unchanged.

Also, if the kthread doesn't start then the hrtimer won't run and the
hardlockup detector will falsely fire.

Signed-off-by: Hillf Danton 
Signed-off-by: Don Zickus 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/watchdog.c: always return NOTIFY_OK during cpu up/down events

2011-03-23T00:44:12+00:00

This patch addresses a couple of problems.  One was the case when the
hardlockup failed to start, it also failed to start the softlockup.  There
were valid cases when the hardlockup shouldn't start and that shouldn't
block the softlockup (no lapic, bios controls perf counters).

The second problem was when the hardlockup failed to start on boxes (from
a no lapic or bios controlled perf counter case), it reported failure to
the cpu notifier chain.  This blocked the notifier from continuing to
start other more critical pieces of cpu bring-up (in our case based on a
2.6.32 fork, it was the mce).  As a result, during soft cpu online/offline
testing, the system would panic when a cpu was offlined because the cpu
notifier would succeed in processing a watchdog disable cpu event and
would panic in the mce case as a result of un-initialized variables from a
never executed cpu up event.

I realized the hardlockup/softlockup cases are really just debugging aids
and should never impede the progress of a cpu up/down event.  Therefore I
modified the code to always return NOTIFY_OK and instead rely on printks
to inform the user of problems.

Signed-off-by: Don Zickus 
Acked-by: Peter Zijlstra 
Reviewed-by: WANG Cong 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/watchdog.c: allow hardlockup to panic by default

2011-03-23T00:44:12+00:00

When a cpu is considered stuck, instead of limping along and just printing
a warning, it is sometimes preferred to just panic, let kdump capture the
vmcore and reboot.  This gets the machine back into a stable state quickly
while saving the info that got it into a stuck state to begin with.

Add a Kconfig option to allow users to set the hardlockup to panic
by default.  Also add in a 'nmi_watchdog=nopanic' to override this.

[akpm@linux-foundation.org: fix strncmp length]
Signed-off-by: Don Zickus 
Acked-by: Peter Zijlstra 
Reviewed-by: WANG Cong 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

watchdog, nmi: Lower the severity of error messages

2011-02-10T12:21:59+00:00

During boot if the hardlockup detector fails to initialize, it
complains very loudly.  Some failures should be expected under
certain situations, ie no lapics, or resource in-use.  Tone
those error messages down a bit.  Keep the rest at a high level.

Reported-by: Paul Bolle 
Tested-by: Paul Bolle 
Signed-off-by: Don Zickus 
Cc: Peter Zijlstra 
LKML-Reference: <1297278153-21111-1-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar

watchdog: Don't change watchdog state on read of sysctl

2011-01-31T12:22:43+00:00

Signed-off-by: Marcin Slusarz 
[ add {}'s to fix a warning ]
Signed-off-by: Don Zickus 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Cc: 
LKML-Reference: <1296230433-6261-3-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar