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  1. 14 5月, 2013 1 次提交
  3. 12 5月, 2013 1 次提交
  5. 05 5月, 2013 1 次提交
  7. 25 4月, 2013 1 次提交
    • T
      clockevents: Set dummy handler on CPU_DEAD shutdown · 6f7a05d7
      由 Thomas Gleixner 提交于 
      Vitaliy reported that a per cpu HPET timer interrupt crashes the
system during hibernation. What happens is that the per cpu HPET timer
gets shut down when the nonboot cpus are stopped. When the nonboot
cpus are onlined again the HPET code sets up the MSI interrupt which
fires before the clock event device is registered. The event handler
is still set to hrtimer_interrupt, which then crashes the machine due
to highres mode not being active.

See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=700333

There is no real good way to avoid that in the HPET code. The HPET
code alrady has a mechanism to detect spurious interrupts when event
handler == NULL for a similar reason.

We can handle that in the clockevent/tick layer and replace the
previous functional handler with a dummy handler like we do in
tick_setup_new_device().

The original clockevents code did this in clockevents_exchange_device(),
but that got removed by commit 7c1e7689 (clockevents: prevent
clockevent event_handler ending up handler_noop) which forgot to fix
it up in tick_shutdown(). Same issue with the broadcast device.
Reported-by: NVitaliy Fillipov <vitalif@yourcmc.ru>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Cc: 700333@bugs.debian.org
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      6f7a05d7
  9. 23 4月, 2013 1 次提交
  11. 18 4月, 2013 3 次提交
  13. 11 4月, 2013 1 次提交
  15. 05 4月, 2013 12 次提交
  17. 26 3月, 2013 1 次提交
  19. 25 3月, 2013 1 次提交
  21. 23 3月, 2013 7 次提交
  23. 16 3月, 2013 1 次提交
    • F
      timekeeping: utilize the suspend-nonstop clocksource to count suspended time · e445cf1c
      由 Feng Tang 提交于 
      There are some new processors whose TSC clocksource won't stop during
suspend. Currently, after system resumes, kernel will use persistent
clock or RTC to compensate the sleep time, but with these nonstop
clocksources, we could skip the special compensation from external
sources, and just use current clocksource for time recounting.

This can solve some time drift bugs caused by some not-so-accurate or
error-prone RTC devices.

The current way to count suspended time is first try to use the persistent
clock, and then try the RTC if persistent clock can't be used. This
patch will change the trying order to:
	suspend-nonstop clocksource -> persistent clock -> RTC

When counting the sleep time with nonstop clocksource, use an accurate way
suggested by Jason Gunthorpe to cover very large delta cycles.
Signed-off-by: NFeng Tang <feng.tang@intel.com>
[jstultz: Small optimization, avoiding re-reading the clocksource]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
      e445cf1c
  25. 13 3月, 2013 3 次提交
    • T
      tick: Provide a check for a forced broadcast pending · eaa907c5
      由 Thomas Gleixner 提交于 
      On the CPU which gets woken along with the target CPU of the broadcast
the following happens:

  deep_idle()
			<-- spurious wakeup
  broadcast_exit()
    set forced bit
  
  enable interrupts
    
			<-- Nothing happens

  disable interrupts

  broadcast_enter()
			<-- Here we observe the forced bit is set
  deep_idle()

Now after that the target CPU of the broadcast runs the broadcast
handler and finds the other CPU in both the broadcast and the forced
mask, sends the IPI and stuff gets back to normal.

So it's not actually harmful, just more evidence for the theory, that
hardware designers have access to very special drug supplies.

Now there is no point in going back to deep idle just to wake up again
right away via an IPI. Provide a check which allows the idle code to
avoid the deep idle transition.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Jason Liu <liu.h.jason@gmail.com>
Link: http://lkml.kernel.org/r/20130306111537.565418308@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      eaa907c5
    • T
      tick: Handle broadcast wakeup of multiple cpus · 989dcb64
      由 Thomas Gleixner 提交于 
      Some brilliant hardware implementations wake multiple cores when the
broadcast timer fires. This leads to the following interesting
problem:

CPU0				CPU1
wakeup from idle		wakeup from idle

leave broadcast mode		leave broadcast mode
 restart per cpu timer		 restart per cpu timer
 	     	 		go back to idle
handle broadcast
 (empty mask)			
				enter broadcast mode
				programm broadcast device
enter broadcast mode
programm broadcast device

So what happens is that due to the forced reprogramming of the cpu
local timer, we need to set a event in the future. Now if we manage to
go back to idle before the timer fires, we switch off the timer and
arm the broadcast device with an already expired time (covered by
forced mode). So in the worst case we repeat the above ping pong
forever.
					
Unfortunately we have no information about what caused the wakeup, but
we can check current time against the expiry time of the local cpu. If
the local event is already in the past, we know that the broadcast
timer is about to fire and send an IPI. So we mark ourself as an IPI
target even if we left broadcast mode and avoid the reprogramming of
the local cpu timer.

This still leaves the possibility that a CPU which is not handling the
broadcast interrupt is going to reach idle again before the IPI
arrives. This can't be solved in the core code and will be handled in
follow up patches.
Reported-by: NJason Liu <liu.h.jason@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Link: http://lkml.kernel.org/r/20130306111537.492045206@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      989dcb64
    • T
      tick: Avoid programming the local cpu timer if broadcast pending · 26517f3e
      由 Thomas Gleixner 提交于 
      If the local cpu timer stops in deep idle, we arm the broadcast device
and get woken by an IPI. Now when we return from deep idle we reenable
the local cpu timer unconditionally before handling the IPI. But
that's a pointless exercise: the timer is already expired and the IPI
is on the way. And it's an expensive exercise as we use the forced
reprogramming mode so that we do not lose a timer event. This forced
reprogramming will loop at least once in the retry.

To avoid this reprogramming, we mark the cpu in a pending bit mask
before we send the IPI. Now when the IPI target cpu wakes up, it will
see the pending bit set and skip the reprogramming. The reprogramming
of the cpu local timer will happen in the IPI handler which runs the
cpu local timer interrupt function.
Reported-by: NJason Liu <liu.h.jason@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Link: http://lkml.kernel.org/r/20130306111537.431082074@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      26517f3e
  27. 08 3月, 2013 1 次提交
    • M
      clockevents: Don't allow dummy broadcast timers · a7dc19b8
      由 Mark Rutland 提交于 
      Currently tick_check_broadcast_device doesn't reject clock_event_devices
with CLOCK_EVT_FEAT_DUMMY, and may select them in preference to real
hardware if they have a higher rating value. In this situation, the
dummy timer is responsible for broadcasting to itself, and the core
clockevents code may attempt to call non-existent callbacks for
programming the dummy, eventually leading to a panic.

This patch makes tick_check_broadcast_device always reject dummy timers,
preventing this problem.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jon Medhurst (Tixy) <tixy@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      a7dc19b8
  29. 07 3月, 2013 3 次提交
  31. 22 2月, 2013 2 次提交
    • T
      Revert "nohz: Make tick_nohz_irq_exit() irq safe" · af7bdbaf
      由 Thomas Gleixner 提交于 
      This reverts commit 351429b2e62b6545bb10c756686393f29ba268a1. The
extra local_irq_save() is not longer needed as the call site now
always calls with interrupts disabled.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
      af7bdbaf
    • F
      nohz: Make tick_nohz_irq_exit() irq safe · e5ab012c
      由 Frederic Weisbecker 提交于 
      As it stands, irq_exit() may or may not be called with
irqs disabled, depending on __ARCH_IRQ_EXIT_IRQS_DISABLED
that the arch can define.

It makes tick_nohz_irq_exit() unsafe. For example two
interrupts can race in tick_nohz_stop_sched_tick(): the inner
most one computes the expiring time on top of the timer list,
then it's interrupted right before reprogramming the
clock. The new interrupt enqueues a new timer list timer,
it reprogram the clock to take it into account and it exits.
The CPUs resumes the inner most interrupt and performs the clock
reprogramming without considering the new timer list timer.

This regression has been introduced by:
     280f0677
     ("nohz: Separate out irq exit and idle loop dyntick logic")

Let's fix it right now with the appropriate protections.

A saner long term solution will be to remove
__ARCH_IRQ_EXIT_IRQS_DISABLED and mandate that irq_exit() is called
with interrupts disabled.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: <stable@vger.kernel.org> #v3.2+
Link: http://lkml.kernel.org/r/1361373336-11337-1-git-send-email-fweisbec@gmail.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      e5ab012c