linux.git/kernel, branch v3.9-rc4

poweroff: change orderly_poweroff() to use schedule_work()

2013-03-22T23:41:20+00:00

David said:

    Commit 6c0c0d4d1080 ("poweroff: fix bug in orderly_poweroff()")
    apparently fixes one bug in orderly_poweroff(), but introduces
    another.  The comments on orderly_poweroff() claim it can be called
    from any context - and indeed we call it from interrupt context in
    arch/powerpc/platforms/pseries/ras.c for example.  But since that
    commit this is no longer safe, since call_usermodehelper_fns() is not
    safe in interrupt context without the UMH_NO_WAIT option.

orderly_poweroff() can be used from any context but UMH_WAIT_EXEC is
sleepable.  Move the "force" logic into __orderly_poweroff() and change
orderly_poweroff() to use the global poweroff_work which simply calls
__orderly_poweroff().

While at it, remove the unneeded "int argc" and change argv_split() to
use GFP_KERNEL.

We use the global "bool poweroff_force" to pass the argument, this can
obviously affect the previous request if it is pending/running.  So we
only allow the "false => true" transition assuming that the pending
"true" should succeed anyway.  If schedule_work() fails after that we
know that work->func() was not called yet, it must see the new value.

This means that orderly_poweroff() becomes async even if we do not run
the command and always succeeds, schedule_work() can only fail if the
work is already pending.  We can export __orderly_poweroff() and change
the non-atomic callers which want the old semantics.

Signed-off-by: Oleg Nesterov 
Reported-by: Benjamin Herrenschmidt 
Reported-by: David Gibson 
Cc: Lucas De Marchi 
Cc: Feng Hong 
Cc: Kees Cook 
Cc: Serge Hallyn 
Cc: "Eric W. Biederman" 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

printk: Provide a wake_up_klogd() off-case

2013-03-22T23:41:20+00:00

wake_up_klogd() is useless when CONFIG_PRINTK=n because neither printk()
nor printk_sched() are in use and there are actually no waiter on
log_wait waitqueue.  It should be a stub in this case for users like
bust_spinlocks().

Otherwise this results in this warning when CONFIG_PRINTK=n and
CONFIG_IRQ_WORK=n:

	kernel/built-in.o In function `wake_up_klogd':
	(.text.wake_up_klogd+0xb4): undefined reference to `irq_work_queue'

To fix this, provide an off-case for wake_up_klogd() when
CONFIG_PRINTK=n.

There is much more from console_unlock() and other console related code
in printk.c that should be moved under CONFIG_PRINTK.  But for now,
focus on a minimal fix as we passed the merged window already.

[akpm@linux-foundation.org: include printk.h in bust_spinlocks.c]
Signed-off-by: Frederic Weisbecker 
Reported-by: James Hogan 
Cc: James Hogan 
Cc: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-03-21T15:29:11+00:00

Pull perf fixes from Ingo Molnar:
 "A fair chunk of the linecount comes from a fix for a tracing bug that
  corrupts latency tracing buffers when the overwrite mode is changed on
  the fly - the rest is mostly assorted fewliner fixlets."

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86: Add SNB/SNB-EP scheduling constraints for cycle_activity event
  kprobes/x86: Check Interrupt Flag modifier when registering probe
  kprobes: Make hash_64() as always inlined
  perf: Generate EXIT event only once per task context
  perf: Reset hwc->last_period on sw clock events
  tracing: Prevent buffer overwrite disabled for latency tracers
  tracing: Keep overwrite in sync between regular and snapshot buffers
  tracing: Protect tracer flags with trace_types_lock
  perf tools: Fix LIBNUMA build with glibc 2.12 and older.
  tracing: Fix free of probe entry by calling call_rcu_sched()
  perf/POWER7: Create a sysfs format entry for Power7 events
  perf probe: Fix segfault
  libtraceevent: Remove hard coded include to /usr/local/include in Makefile
  perf record: Fix -C option
  perf tools: check if -DFORTIFY_SOURCE=2 is allowed
  perf report: Fix build with NO_NEWT=1
  perf annotate: Fix build with NO_NEWT=1
  tracing: Fix race in snapshot swapping

Merge branch 'for-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2013-03-19T01:47:07+00:00

Pull workqueue fix from Tejun Heo:
 "Lai's patch to fix highly unlikely but still possible workqueue stall
  during CPU hotunplug."

* 'for-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: fix possible pool stall bug in wq_unbind_fn()

Merge branch 'tip/perf/urgent-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/urgent

2013-03-18T08:48:29+00:00

Pull tracing fixes from Steven Rostedt.

Signed-off-by: Ingo Molnar

perf: Generate EXIT event only once per task context

2013-03-18T08:47:33+00:00

perf_event_task_event() iterates pmu list and generate events
for each eligible pmu context.  But if task_event has task_ctx
like in EXIT it'll generate events even though the pmu doesn't
have an eligible one. Fix it by moving the code to proper
places.

Before this patch:

  $ perf record -n true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.006 MB perf.data (~248 samples) ]

  $ perf report -D | tail
  Aggregated stats:
             TOTAL events:         73
              MMAP events:         67
              COMM events:          2
              EXIT events:          4
  cycles stats:
             TOTAL events:         73
              MMAP events:         67
              COMM events:          2
              EXIT events:          4

After this patch:

  $ perf report -D | tail
  Aggregated stats:
             TOTAL events:         70
              MMAP events:         67
              COMM events:          2
              EXIT events:          1
  cycles stats:
             TOTAL events:         70
              MMAP events:         67
              COMM events:          2
              EXIT events:          1

Signed-off-by: Namhyung Kim 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1363332433-7637-1-git-send-email-namhyung@kernel.org
Signed-off-by: Ingo Molnar

perf: Reset hwc->last_period on sw clock events

2013-03-18T08:15:18+00:00

When cpu/task clock events are initialized, their sampling
frequencies are converted to have a fixed value.  However it
missed to update the hwc->last_period which was set to 1 for
initial sampling frequency calibration.

Because this hwc->last_period value is used as a period in
perf_swevent_ hrtime(), every recorded sample will have an
incorrected period of 1.

  $ perf record -e task-clock noploop 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.158 MB perf.data (~6919 samples) ]

  $ perf report -n --show-total-period  --stdio
  # Samples: 4K of event 'task-clock'
  # Event count (approx.): 4000
  #
  # Overhead       Samples        Period  Command  Shared Object              Symbol
  # ........  ............  ............  .......  .............  ..................
  #
      99.95%          3998          3998  noploop  noploop        [.] main
       0.03%             1             1  noploop  libc-2.15.so   [.] init_cacheinfo
       0.03%             1             1  noploop  ld-2.15.so     [.] open_verify

Note that it doesn't affect the non-sampling event so that the
perf stat still gets correct value with or without this patch.

  $ perf stat -e task-clock noploop 1

   Performance counter stats for 'noploop 1':

         1000.272525 task-clock                #    1.000 CPUs utilized

         1.000560605 seconds time elapsed

Signed-off-by: Namhyung Kim 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1363574507-18808-1-git-send-email-namhyung@kernel.org
Signed-off-by: Ingo Molnar

tracing: Prevent buffer overwrite disabled for latency tracers

2013-03-15T03:40:21+00:00

The latency tracers require the buffers to be in overwrite mode,
otherwise they get screwed up. Force the buffers to stay in overwrite
mode when latency tracers are enabled.

Added a flag_changed() method to the tracer structure to allow
the tracers to see what flags are being changed, and also be able
to prevent the change from happing.

Cc: stable@vger.kernel.org
Signed-off-by: Steven Rostedt

tracing: Keep overwrite in sync between regular and snapshot buffers

2013-03-15T03:40:15+00:00

Changing the overwrite mode for the ring buffer via the trace
option only sets the normal buffer. But the snapshot buffer could
swap with it, and then the snapshot would be in non overwrite mode
and the normal buffer would be in overwrite mode, even though the
option flag states otherwise.

Keep the two buffers overwrite modes in sync.

Cc: stable@vger.kernel.org
Signed-off-by: Steven Rostedt

tracing: Protect tracer flags with trace_types_lock

2013-03-14T17:50:56+00:00

Seems that the tracer flags have never been protected from
synchronous writes. Luckily, admins don't usually modify the
tracing flags via two different tasks. But if scripts were to
be used to modify them, then they could get corrupted.

Move the trace_types_lock that protects against tracers changing
to also protect the flags being set.

Cc: stable@vger.kernel.org
Signed-off-by: Steven Rostedt