The panic notifer in lockup_detector just set did_panic to 1.
But did_panic is not used anywhere so we can just remove it.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: peterz@infradead.org
Cc: gorcunov@gmail.com
Cc: fweisbec@gmail.com
LKML-Reference: <1283310009-22168-4-git-send-email-dzickus@redhat.com>
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

By the commit e6bde73b
("cpu-hotplug: return better errno on cpu hotplug failure"),
the cpu notifier can return encapsulate errno value, resulting
in more meaningful error codes for CPU hotplug failures.

This converts the cpu notifier to return encapsulate errno value
for the lockup_detector as well.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: peterz@infradead.org
Cc: gorcunov@gmail.com
Cc: fweisbec@gmail.com
LKML-Reference: <1283310009-22168-3-git-send-email-dzickus@redhat.com>
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Stephane reported that when the machine locks up, the regular ticks,
which are responsible to resetting the throttle count, stop too.

Hence the NMI watchdog can end up being throttled before it reports on
the locked up state, and we end up being sad..

Cure this by having the watchdog overflow reset its own throttle count.
Reported-by: NStephane Eranian <eranian@google.com>
Tested-by: NStephane Eranian <eranian@google.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1282215916.1926.4696.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Variable on the stack is not initialized to zero, do it
explicitly.

This bug was found by a compiler warning:

 kernel/watchdog.c:463: warning: 'result' may be used uninitialized in this function
Signed-off-by: NKulikov Vasiliy <segooon@gmail.com>
Acked-by: NDon Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1278316854-28442-1-git-send-email-segooon@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Just a bunch of conversions as suggested by Frederic W.
__get_cpu_var() provides preemption disabled checks.

Plus it gives more readability as it makes it obvious
we are dealing locally now with these vars.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
LKML-Reference: <1274133966-18415-2-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

Combining the softlockup and hardlockup code causes watchdog.c
to build even without the hardlockup detection support.

So if an arch, that has the previous and the new nmi watchdog
implementations cohabiting, wants to know if the generic one
is in use, CONFIG_LOCKUP_DETECTOR is not a reliable check.
We need to use CONFIG_HARDLOCKUP_DETECTOR instead.

Fixes:
	kernel/built-in.o: In function `touch_nmi_watchdog':
	(.text+0x449bc): multiple definition of `touch_nmi_watchdog'
	arch/sparc/kernel/built-in.o:(.text+0x11b28): first defined here
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
LKML-Reference: <20100514151121.GR15159@redhat.com>
[ use CONFIG_HARDLOCKUP_DETECTOR instead of CONFIG_PERF_EVENTS_NMI]
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

This new config is deemed to simplify even more the lockup detector
dependencies and can make it easier to bring a smooth sorting
between archs that support the new generic lockup detector and those
that still have their own, especially for those that are in the
middle of this migration.

Instead of checking whether we have CONFIG_LOCKUP_DETECTOR +
CONFIG_PERF_EVENTS_NMI each time an arch wants to know if it needs
to build its own lockup detector, take a shortcut with this new
config. It is enabled only if the hardlockup detection part of
the whole lockup detector is on.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>

There are modules that rely on it:

  ERROR: "touch_softlockup_watchdog" [drivers/video/nvidia/nvidiafb.ko] undefined!

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
LKML-Reference: <1273713674-8434-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When I combined the nmi_watchdog (hardlockup) and softlockup code, I
also combined the paths the touch_watchdog and touch_nmi_watchdog took.
This may not be the best idea as pointed out by Frederic W., that the
touch_watchdog case probably should not reset the hardlockup count.

Therefore the patch below falls back to the previous idea of keeping
the touch_nmi_watchdog a superset of the touch_watchdog case.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-9-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

Just some code cleanup to make touch_softlockup clearer and remove the
softlockup_tick function as it is no longer needed.

Also remove the /proc softlockup_thres call as it has been changed to
watchdog_thres.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-3-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

The new nmi_watchdog (which uses the perf event subsystem) is very
similar in structure to the softlockup detector.  Using Ingo's
suggestion, I combined the two functionalities into one file:
kernel/watchdog.c.

Now both the nmi_watchdog (or hardlockup detector) and softlockup
detector sit on top of the perf event subsystem, which is run every
60 seconds or so to see if there are any lockups.

To detect hardlockups, cpus not responding to interrupts, I
implemented an hrtimer that runs 5 times for every perf event
overflow event.  If that stops counting on a cpu, then the cpu is
most likely in trouble.

To detect softlockups, tasks not yielding to the scheduler, I used the
previous kthread idea that now gets kicked every time the hrtimer fires.
If the kthread isn't being scheduled neither is anyone else and the
warning is printed to the console.

I tested this on x86_64 and both the softlockup and hardlockup paths
work.

V2:
- cleaned up the Kconfig and softlockup combination
- surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI
- seperated out the softlockup case from perf event subsystem
- re-arranged the enabling/disabling nmi watchdog from proc space
- added cpumasks for hardlockup failure cases
- removed fallback to soft events if no PMU exists for hard events

V3:
- comment cleanups
- drop support for older softlockup code
- per_cpu cleanups
- completely remove software clock base hardlockup detector
- use per_cpu masking on hard/soft lockup detection
- #ifdef cleanups
- rename config option NMI_WATCHDOG to LOCKUP_DETECTOR
- documentation additions

V4:
- documentation fixes
- convert per_cpu to __get_cpu_var
- powerpc compile fixes

V5:
- split apart warn flags for hard and soft lockups

TODO:
- figure out how to make an arch-agnostic clock2cycles call
  (if possible) to feed into perf events as a sample period

[fweisbec: merged conflict patch]
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>