linux-toradex.git/kernel/watchdog.c, branch v2.6.39-rc2

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

watchdog: Fix sysctl consistency

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

If it was not possible to enable watchdog for any cpu, switch
watchdog_enabled back to 0, because it's visible via
kernel.watchdog sysctl.

Signed-off-by: Marcin Slusarz 
Signed-off-by: Don Zickus 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Cc: 
LKML-Reference: <1296230433-6261-2-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar

watchdog: Fix broken nowatchdog logic

2011-01-31T12:22:42+00:00

Passing nowatchdog to kernel disables 2 things: creation of
watchdog threads AND initialization of percpu watchdog_hrtimer.
As hrtimers are initialized only at boot it's not possible to
enable watchdog later - for me all watchdog threads started to
eat 100% of CPU time, but they could just crash.

Additionally, even if these threads would start properly,
watchdog_disable_all_cpus was guarded by no_watchdog check, so
you couldn't disable watchdog.

To fix this, remove no_watchdog variable and use already
existing watchdog_enabled variable.

Signed-off-by: Marcin Slusarz 
[ removed another no_watchdog instance ]
Signed-off-by: Don Zickus 
Cc: Stephane Eranian 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Cc: 
LKML-Reference: <1296230433-6261-1-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar

Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2011-01-08T01:02:58+00:00

* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)
  gameport: use this_cpu_read instead of lookup
  x86: udelay: Use this_cpu_read to avoid address calculation
  x86: Use this_cpu_inc_return for nmi counter
  x86: Replace uses of current_cpu_data with this_cpu ops
  x86: Use this_cpu_ops to optimize code
  vmstat: User per cpu atomics to avoid interrupt disable / enable
  irq_work: Use per cpu atomics instead of regular atomics
  cpuops: Use cmpxchg for xchg to avoid lock semantics
  x86: this_cpu_cmpxchg and this_cpu_xchg operations
  percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support
  percpu,x86: relocate this_cpu_add_return() and friends
  connector: Use this_cpu operations
  xen: Use this_cpu_inc_return
  taskstats: Use this_cpu_ops
  random: Use this_cpu_inc_return
  fs: Use this_cpu_inc_return in buffer.c
  highmem: Use this_cpu_xx_return() operations
  vmstat: Use this_cpu_inc_return for vm statistics
  x86: Support for this_cpu_add, sub, dec, inc_return
  percpu: Generic support for this_cpu_add, sub, dec, inc_return
  ...

Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}
as per Tejun.

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2011-01-06T18:23:33+00:00

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (30 commits)
  sched: Change wait_for_completion_*_timeout() to return a signed long
  sched, autogroup: Fix reference leak
  sched, autogroup: Fix potential access to freed memory
  sched: Remove redundant CONFIG_CGROUP_SCHED ifdef
  sched: Fix interactivity bug by charging unaccounted run-time on entity re-weight
  sched: Move periodic share updates to entity_tick()
  printk: Use this_cpu_{read|write} api on printk_pending
  sched: Make pushable_tasks CONFIG_SMP dependant
  sched: Add 'autogroup' scheduling feature: automated per session task groups
  sched: Fix unregister_fair_sched_group()
  sched: Remove unused argument dest_cpu to migrate_task()
  mutexes, sched: Introduce arch_mutex_cpu_relax()
  sched: Add some clock info to sched_debug
  cpu: Remove incorrect BUG_ON
  cpu: Remove unused variable
  sched: Fix UP build breakage
  sched: Make task dump print all 15 chars of proc comm
  sched: Update tg->shares after cpu.shares write
  sched: Allow update_cfs_load() to update global load
  sched: Implement demand based update_cfs_load()
  ...

Merge commit 'v2.6.37' into perf/core

2011-01-05T13:22:10+00:00

Merge reason: Add the final .37 tree.

Signed-off-by: Ingo Molnar

Merge commit 'v2.6.37' into sched/core

2011-01-05T13:14:46+00:00

Merge reason: Merge the final .37 tree.

Signed-off-by: Ingo Molnar