Commit Graph

147 Commits

Author SHA1 Message Date
Thomas Gleixner
6ff7041dbf hrtimer: Fix migration expiry check
The timer migration expiry check should prevent the migration of a
timer to another CPU when the timer expires before the next event is
scheduled on the other CPU. Migrating the timer might delay it because
we can not reprogram the clock event device on the other CPU. But the
code implementing that check has two flaws:

- for !HIGHRES the check compares the expiry value with the clock
  events device expiry value which is wrong for CLOCK_REALTIME based
  timers.

- the check is racy. It holds the hrtimer base lock of the target CPU,
  but the clock event device expiry value can be modified
  nevertheless, e.g. by an timer interrupt firing.

The !HIGHRES case is easy to fix as we can enqueue the timer on the
cpu which was selected by the load balancer. It runs the idle
balancing code once per jiffy anyway. So the maximum delay for the
timer is the same as when we keep the tick on the current cpu going.

In the HIGHRES case we can get the next expiry value from the hrtimer
cpu_base of the target CPU and serialize the update with the cpu_base
lock. This moves the lock section in hrtimer_interrupt() so we can set
next_event to KTIME_MAX while we are handling the expired timers and
set it to the next expiry value after we handled the timers under the
base lock. While the expired timers are processed timer migration is
blocked because the expiry time of the timer is always <= KTIME_MAX.

Also remove the now useless clockevents_get_next_event() function.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-07-10 17:32:55 +02:00
Thomas Gleixner
7e0c5086c1 hrtimer: migration: do not check expiry time on current CPU
The timer migration code needs to check whether the expiry time of the
timer is before the programmed clock event expiry time when the timer
is enqueued on another CPU because we can not reprogram the timer
device on the other CPU. The current logic checks the expiry time even
if we enqueue on the current CPU when nohz_get_load_balancer() returns
current CPU. This might lead to an endless loop in the expiry check
code when the expiry time of the timer is before the current
programmed next event.

Check whether nohz_get_load_balancer() returns current CPU and skip
the expiry check if this is the case.

The bug was triggered from the networking code. The patch fixes the
regression http://bugzilla.kernel.org/show_bug.cgi?id=13738
(Soft-Lockup/Race in networking in 2.6.31-rc1+195)

Cc: Arun Bharadwaj <arun@linux.vnet.ibm.com
Tested-by: Joao Correia <joaomiguelcorreia@gmail.com>
Tested-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-07-10 17:22:20 +02:00
Linus Torvalds
b7c142dbf1 Merge branch 'linux-next' of git://git.infradead.org/ubifs-2.6
* 'linux-next' of git://git.infradead.org/ubifs-2.6:
  UBIFS: start using hrtimers
  hrtimer: export ktime_add_safe
  UBIFS: do not forget to register BDI device
  UBIFS: allow sync option in rootflags
  UBIFS: remove dead code
  UBIFS: use anonymous device
  UBIFS: return proper error code if the compr is not present
  UBIFS: return error if link and unlink race
  UBIFS: reset no_space flag after inode deletion
2009-06-17 09:46:33 -07:00
Artem Bityutskiy
8daa21e61b hrtimer: export ktime_add_safe
We want to use hrtimers in UBIFS (for write-buffer write-back timer).
We need the 'hrtimer_set_expires_range_ns()', which is an in-line
function which uses 'ktime_add_safe()'.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
2009-06-08 11:14:58 +03:00
Arun R Bharadwaj
eea08f32ad timers: Logic to move non pinned timers
* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]:

This patch migrates all non pinned timers and hrtimers to the current
idle load balancer, from all the idle CPUs. Timers firing on busy CPUs
are not migrated.

While migrating hrtimers, care should be taken to check if migrating
a hrtimer would result in a latency or not. So we compare the expiry of the
hrtimer with the next timer interrupt on the target cpu and migrate the
hrtimer only if it expires *after* the next interrupt on the target cpu.
So, added a clockevents_get_next_event() helper function to return the
next_event on the target cpu's clock_event_device.

[ tglx: cleanups and simplifications ]

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-05-13 16:52:42 +02:00
Arun R Bharadwaj
597d027573 timers: Framework for identifying pinned timers
* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]:

This patch creates a new framework for identifying cpu-pinned timers
and hrtimers.

This framework is needed because pinned timers are expected to fire on
the same CPU on which they are queued. So it is essential to identify
these and not migrate them, in case there are any.

For regular timers, the currently existing add_timer_on() can be used
queue pinned timers and subsequently mod_timer_pinned() can be used
to modify the 'expires' field.

For hrtimers, new modes HRTIMER_ABS_PINNED and HRTIMER_REL_PINNED are
added to queue cpu-pinned hrtimer.

[ tglx: use .._PINNED mode argument instead of creating tons of new
functions ]

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-05-13 16:52:42 +02:00
Peter Zijlstra
7f1e2ca9f0 hrtimer: fix rq->lock inversion (again)
It appears I inadvertly introduced rq->lock recursion to the
hrtimer_start() path when I delegated running already expired
timers to softirq context.

This patch fixes it by introducing a __hrtimer_start_range_ns()
method that will not use raise_softirq_irqoff() but
__raise_softirq_irqoff() which avoids the wakeup.

It then also changes schedule() to check for pending softirqs and
do the wakeup then, I'm not quite sure I like this last bit, nor
am I convinced its really needed.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
LKML-Reference: <20090313112301.096138802@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-31 14:52:52 +02:00
Thomas Gleixner
b0a9b5111a hrtimer: prevent negative expiry value after clock_was_set()
Impact: prevent false positive WARN_ON() in clockevents_program_event()

clock_was_set() changes the base->offset of CLOCK_REALTIME and
enforces the reprogramming of the clockevent device to expire timers
which are based on CLOCK_REALTIME. If the clock change is large enough
then the subtraction of the timer expiry value and base->offset can
become negative which triggers the warning in
clockevents_program_event().

Check the subtraction result and set a negative value to 0.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-01-30 22:35:34 +01:00
Sebastien Dugue
94df7de028 hrtimers: allow the hot-unplugging of all cpus
Impact: fix CPU hotplug hang on Power6 testbox

On architectures that support offlining all cpus (at least powerpc/pseries),
hot-unpluging the tick_do_timer_cpu can result in a system hang.

This comes from the fact that if the cpu going down happens to be the
cpu doing the tick, then as the tick_do_timer_cpu handover happens after the
cpu is dead (via the CPU_DEAD notification), we're left without ticks,
jiffies are frozen and any task relying on timers (msleep, ...) is stuck.
That's particularly the case for the cpu looping in __cpu_die() waiting
for the dying cpu to be dead.

This patch addresses this by having the tick_do_timer_cpu handover happen
earlier during the CPU_DYING notification. For this, a new clockevent
notification type is introduced (CLOCK_EVT_NOTIFY_CPU_DYING) which is triggered
in hrtimer_cpu_notify().

Signed-off-by: Sebastien Dugue <sebastien.dugue@bull.net>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-30 22:35:29 +01:00
Frederic Weisbecker
7f22391cbe hrtimers: increase clock min delta threshold while interrupt hanging
Impact: avoid timer IRQ hanging slow systems

While using the function graph tracer on a virtualized system, the
hrtimer_interrupt can hang the system on an infinite loop.

This can be caused in several situations:

 - the hardware is very slow and HZ is set too high

 - something intrusive is slowing the system down (tracing under emulation)

... and the next clock events to program are always before the current time.

This patch implements a reasonable compromise: if such a situation is
detected, we share the CPUs time in 1/4 to process the hrtimer interrupts.
This is enough to let the system running without serious starvation.

It has been successfully tested under VirtualBox with 1000 HZ and 100 HZ
with function graph tracer launched. On both cases, the clock events were
increased until about 25 ms periodic ticks, which means 40 HZ.

So we change a hard to debug hang into a warning message and a system that
still manages to limp along.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-30 22:35:10 +01:00
Linus Torvalds
1e70c7f7a9 Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimers: fix inconsistent lock state on resume in hres_timers_resume
  time-sched.c: tick_nohz_update_jiffies should be static
  locking, hpet: annotate false positive warning
  kernel/fork.c: unused variable 'ret'
  itimers: remove the per-cpu-ish-ness
2009-01-26 09:47:43 -08:00
Peter Zijlstra
1d4a7f1c4f hrtimers: fix inconsistent lock state on resume in hres_timers_resume
Andrey Borzenkov reported this lockdep assert:

> [17854.688347] =================================
> [17854.688347] [ INFO: inconsistent lock state ]
> [17854.688347] 2.6.29-rc2-1avb #1
> [17854.688347] ---------------------------------
> [17854.688347] inconsistent {in-hardirq-W} -> {hardirq-on-W} usage.
> [17854.688347] pm-suspend/18240 [HC0[0]:SC0[0]:HE1:SE1] takes:
> [17854.688347]  (&cpu_base->lock){++..}, at: [<c0136fcc>] retrigger_next_event+0x5c/0xa0
> [17854.688347] {in-hardirq-W} state was registered at:
> [17854.688347]   [<c01443cd>] __lock_acquire+0x79d/0x1930
> [17854.688347]   [<c01455bc>] lock_acquire+0x5c/0x80
> [17854.688347]   [<c03092e5>] _spin_lock+0x35/0x70
> [17854.688347]   [<c0136e61>] hrtimer_run_queues+0x31/0x140
> [17854.688347]   [<c0128d98>] run_local_timers+0x8/0x20
> [17854.688347]   [<c0128dd3>] update_process_times+0x23/0x60
> [17854.688347]   [<c013e274>] tick_periodic+0x24/0x80
> [17854.688347]   [<c013e2e2>] tick_handle_periodic+0x12/0x70
> [17854.688347]   [<c0104e24>] timer_interrupt+0x14/0x20
> [17854.688347]   [<c01607b9>] handle_IRQ_event+0x29/0x60
> [17854.688347]   [<c0161c59>] handle_level_irq+0x69/0xe0
> [17854.688347]   [<ffffffff>] 0xffffffff
> [17854.688347] irq event stamp: 55771
> [17854.688347] hardirqs last  enabled at (55771): [<c0309125>] _spin_unlock_irqrestore+0x35/0x60
> [17854.688347] hardirqs last disabled at (55770): [<c0309419>] _spin_lock_irqsave+0x19/0x80
> [17854.688347] softirqs last  enabled at (54836): [<c0124f54>] __do_softirq+0xc4/0x110
> [17854.688347] softirqs last disabled at (54831): [<c01049ae>] do_softirq+0x8e/0xe0
> [17854.688347]
> [17854.688347] other info that might help us debug this:
> [17854.688347] 3 locks held by pm-suspend/18240:
> [17854.688347]  #0:  (&buffer->mutex){--..}, at: [<c01dd4c5>] sysfs_write_file+0x25/0x100
> [17854.688347]  #1:  (pm_mutex){--..}, at: [<c015056f>] enter_state+0x4f/0x140
> [17854.688347]  #2:  (dpm_list_mtx){--..}, at: [<c027880f>] device_pm_lock+0xf/0x20
> [17854.688347]
> [17854.688347] stack backtrace:
> [17854.688347] Pid: 18240, comm: pm-suspend Not tainted 2.6.29-rc2-1avb #1
> [17854.688347] Call Trace:
> [17854.688347]  [<c0306248>] ? printk+0x18/0x20
> [17854.688347]  [<c0141fac>] print_usage_bug+0x16c/0x1d0
> [17854.688347]  [<c0142bcf>] mark_lock+0x8bf/0xc90
> [17854.688347]  [<c0106b8f>] ? pit_next_event+0x2f/0x40
> [17854.688347]  [<c01441b0>] __lock_acquire+0x580/0x1930
> [17854.688347]  [<c030916d>] ? _spin_unlock+0x1d/0x20
> [17854.688347]  [<c0106b8f>] ? pit_next_event+0x2f/0x40
> [17854.688347]  [<c013dd38>] ? clockevents_program_event+0x98/0x160
> [17854.688347]  [<c0142fe8>] ? mark_held_locks+0x48/0x90
> [17854.688347]  [<c0309125>] ? _spin_unlock_irqrestore+0x35/0x60
> [17854.688347]  [<c0143229>] ? trace_hardirqs_on_caller+0x139/0x190
> [17854.688347]  [<c014328b>] ? trace_hardirqs_on+0xb/0x10
> [17854.688347]  [<c01455bc>] lock_acquire+0x5c/0x80
> [17854.688347]  [<c0136fcc>] ? retrigger_next_event+0x5c/0xa0
> [17854.688347]  [<c03092e5>] _spin_lock+0x35/0x70
> [17854.688347]  [<c0136fcc>] ? retrigger_next_event+0x5c/0xa0
> [17854.688347]  [<c0136fcc>] retrigger_next_event+0x5c/0xa0
> [17854.688347]  [<c013711a>] hres_timers_resume+0xa/0x10
> [17854.688347]  [<c013aa8e>] timekeeping_resume+0xee/0x150
> [17854.688347]  [<c0273384>] __sysdev_resume+0x14/0x50
> [17854.688347]  [<c0273407>] sysdev_resume+0x47/0x80
> [17854.688347]  [<c02791ab>] device_power_up+0xb/0x20
> [17854.688347]  [<c015043f>] suspend_devices_and_enter+0xcf/0x150
> [17854.688347]  [<c0150c2f>] ? freeze_processes+0x3f/0x90
> [17854.688347]  [<c0150614>] enter_state+0xf4/0x140
> [17854.688347]  [<c01506dd>] state_store+0x7d/0xc0
> [17854.688347]  [<c0150660>] ? state_store+0x0/0xc0
> [17854.688347]  [<c0202da4>] kobj_attr_store+0x24/0x30
> [17854.688347]  [<c01dd53c>] sysfs_write_file+0x9c/0x100
> [17854.688347]  [<c019916c>] vfs_write+0x9c/0x160
> [17854.688347]  [<c0103494>] ? restore_nocheck_notrace+0x0/0xe
> [17854.688347]  [<c01dd4a0>] ? sysfs_write_file+0x0/0x100
> [17854.688347]  [<c01992ed>] sys_write+0x3d/0x70
> [17854.688347]  [<c0103371>] sysenter_do_call+0x12/0x31

Andrey's analysis:

> timekeeping_resume() is called via class ->resume
> method; and according to comments in sysdev_resume() and
> device_power_up(), they are called with interrupts disabled.
>
> Looking at suspend_enter, irqs *are* disabled at this point.
>
> So it actually looks like something (may be some driver)
> unconditionally enabled irqs in resume path.

Add a debug check to test this theory. If it triggers then it
triggers because the resume code calls it with irqs enabled,
which is a no-no not just for timekeeping_resume(), but also
bad for a number of other resume handlers.

Reported-by: Andrey Borzenkov <arvidjaar@mail.ru>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-18 21:31:37 +01:00
Heiko Carstens
58fd3aa288 [CVE-2009-0029] System call wrappers part 01
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2009-01-14 14:15:18 +01:00
Ingo Molnar
82c5b7b527 hrtimer: splitout peek ahead functionality, fix
Impact: build fix on !CONFIG_HIGH_RES_TIMERS

Fix:

  kernel/hrtimer.c:1586: error: implicit declaration of function '__hrtimer_peek_ahead_timers'

Signen-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-05 14:11:10 +01:00
Thomas Gleixner
e3f1d88374 hrtimer: fixup comments
Clean up the comments

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-05 13:14:34 +01:00
Peter Zijlstra
a6037b61c2 hrtimer: fix recursion deadlock by re-introducing the softirq
Impact: fix rare runtime deadlock

There are a few sites that do:

  spin_lock_irq(&foo)
  hrtimer_start(&bar)
    __run_hrtimer(&bar)
      func()
        spin_lock(&foo)

which obviously deadlocks. In order to avoid this, never call __run_hrtimer()
from hrtimer_start*() context, but instead defer this to softirq context.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-05 13:14:33 +01:00
Thomas Gleixner
731a55ba0f hrtimer: simplify hotplug migration
Impact: cleanup

No need for a smp function call, which is likely to run on the same
CPU anyway. We can just call hrtimers_peek_ahead() in the interrupts
disabled section of migrate_hrtimers().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-05 13:14:33 +01:00
Thomas Gleixner
d5fd43c4ae hrtimer: fix HOTPLUG_CPU=n compile warning
Impact: cleanup

 kernel/hrtimer.c: In function 'hrtimer_cpu_notify':
 kernel/hrtimer.c:1574: warning: unused variable 'dcpu'

Introduced by commit 37810659ea
("hrtimer: removing all ur callback modes, fix hotplug") from the
timers.  dcpu is only used if CONFIG_HOTPLUG_CPU is set.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-05 13:14:32 +01:00
Thomas Gleixner
8bdec955b0 hrtimer: splitout peek ahead functionality
Impact: cleanup

Provide a peek ahead function that assumes irqs disabled, allows for micro
optimizations.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-05 13:14:32 +01:00
Linus Torvalds
db200df0b3 Merge branch 'irq-fixes-for-linus-4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'irq-fixes-for-linus-4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sparseirq: move __weak symbols into separate compilation unit
  sparseirq: work around __weak alias bug
  sparseirq: fix hang with !SPARSE_IRQ
  sparseirq: set lock_class for legacy irq when sparse_irq is selected
  sparseirq: work around compiler optimizing away __weak functions
  sparseirq: fix desc->lock init
  sparseirq: do not printk when migrating IRQ descriptors
  sparseirq: remove duplicated arch_early_irq_init()
  irq: simplify for_each_irq_desc() usage
  proc: remove ifdef CONFIG_SPARSE_IRQ from stat.c
  irq: for_each_irq_desc() move to irqnr.h
  hrtimer: remove #include <linux/irq.h>
2008-12-31 09:00:59 -08:00
KOSAKI Motohiro
51bc39f4ba hrtimer: remove #include <linux/irq.h>
Impact: cleanup

<linux/irq.h> can be removed and should be, because:

  - hrtimer doesn't use any irq feature.
  - <linux/irq.h> shouldn't be include from generic code.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-26 09:48:16 +01:00
Ingo Molnar
b2e3c0adec hrtimers: fix warning in kernel/hrtimer.c
this warning:

  kernel/hrtimer.c: In function ‘hrtimer_cpu_notify’:
  kernel/hrtimer.c:1574: warning: unused variable ‘dcpu’

is caused because 'dcpu' is only used in the CONFIG_HOTPLUG_CPU case.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-19 00:45:32 +01:00
Peter Zijlstra
a0a99b227d hrtimer: removing all ur callback modes, fix
> Ingo, this addition fixes the hotplug issue on my machine

And because we're all human...

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-08 17:20:38 +01:00
Peter Zijlstra
37810659ea hrtimer: removing all ur callback modes, fix hotplug
Impact: fix hrtimer locking (reported by lockdep) in the CPU hotplug case

This addition fixes the hotplug locking issue on my machine

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-04 11:31:25 +01:00
Peter Zijlstra
ca109491f6 hrtimer: removing all ur callback modes
Impact: cleanup, move all hrtimer processing into hardirq context

This is an attempt at removing some of the hrtimer complexity by
reducing the number of callback modes to 1.

This means that all hrtimer callback functions will be ran from HARD-irq
context.

I went through all the 30 odd hrtimer callback functions in the kernel
and saw only one that I'm not quite sure of, which is the one in
net/can/bcm.c - hence I'm CC-ing the folks responsible for that code.

Furthermore, the hrtimer core now calls callbacks directly with IRQs
disabled in case you try to enqueue an expired timer. If this timer is a
periodic timer (which should use hrtimer_forward() to advance its time)
then it might be possible to end up in an inf. recursive loop due to the
fact that hrtimer_forward() doesn't round up to the next timer
granularity, and therefore keeps on calling the callback - obviously
this needs a fix.

Aside from that, this seems to compile and actually boot on my dual core
test box - although I'm sure there are some bugs in, me not hitting any
makes me certain :-)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-25 15:45:46 +01:00
Peter Zijlstra
621a0d5207 hrtimer: clean up unused callback modes
Impact: cleanup

git grep HRTIMER_CB_IRQSAFE revealed half the callback modes are actually
unused.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-12 09:54:40 +01:00
Gautham R Shenoy
5d5254f0d3 timers: handle HRTIMER_CB_IRQSAFE_UNLOCKED correctly from softirq context
Impact: fix incorrect locking triggered during hotplug-intense stress-tests

While migrating the the CB_IRQSAFE_UNLOCKED timers during a cpu-offline,
we queue them on the cb_pending list, so that they won't go
stale.

Thus, when the callbacks of the timers run from the softirq context,
they could run into potential deadlocks, since these callbacks
assume that they're running with irq's disabled, thereby annoying
lockdep!

Fix this by emulating hardirq context while running these callbacks from
the hrtimer softirq.

=================================
[ INFO: inconsistent lock state ]
2.6.27 #2
--------------------------------
inconsistent {in-hardirq-W} -> {hardirq-on-W} usage.
ksoftirqd/0/4 [HC0[0]:SC1[1]:HE1:SE0] takes:
 (&rq->lock){++..}, at: [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
{in-hardirq-W} state was registered at:
  [<c014103c>] __lock_acquire+0x549/0x121e
  [<c0107890>] native_sched_clock+0x88/0x99
  [<c013aa12>] clocksource_get_next+0x39/0x3f
  [<c0139abc>] update_wall_time+0x616/0x7df
  [<c0141d6b>] lock_acquire+0x5a/0x74
  [<c0121724>] scheduler_tick+0x3a/0x18d
  [<c047ed45>] _spin_lock+0x1c/0x45
  [<c0121724>] scheduler_tick+0x3a/0x18d
  [<c0121724>] scheduler_tick+0x3a/0x18d
  [<c012c436>] update_process_times+0x3a/0x44
  [<c013c044>] tick_periodic+0x63/0x6d
  [<c013c062>] tick_handle_periodic+0x14/0x5e
  [<c010568c>] timer_interrupt+0x44/0x4a
  [<c0150c9f>] handle_IRQ_event+0x13/0x3d
  [<c0151c14>] handle_level_irq+0x79/0xbd
  [<c0105634>] do_IRQ+0x69/0x7d
  [<c01041e4>] common_interrupt+0x28/0x30
  [<c047007b>] aac_probe_one+0x1a3/0x3f3
  [<c047ec2d>] _spin_unlock_irqrestore+0x36/0x39
  [<c01512b4>] setup_irq+0x1be/0x1f9
  [<c065d70b>] start_kernel+0x259/0x2c5
  [<ffffffff>] 0xffffffff
irq event stamp: 50102
hardirqs last  enabled at (50102): [<c047ebf4>] _spin_unlock_irq+0x20/0x23
hardirqs last disabled at (50101): [<c047edc2>] _spin_lock_irq+0xa/0x4b
softirqs last  enabled at (50088): [<c0128ba6>] do_softirq+0x37/0x4d
softirqs last disabled at (50099): [<c0128ba6>] do_softirq+0x37/0x4d

other info that might help us debug this:
no locks held by ksoftirqd/0/4.

stack backtrace:
Pid: 4, comm: ksoftirqd/0 Not tainted 2.6.27 #2
 [<c013f6cb>] print_usage_bug+0x13e/0x147
 [<c013fef5>] mark_lock+0x493/0x797
 [<c01410b1>] __lock_acquire+0x5be/0x121e
 [<c0141d6b>] lock_acquire+0x5a/0x74
 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
 [<c047ed45>] _spin_lock+0x1c/0x45
 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
 [<c01210fd>] finish_task_switch+0x41/0xbd
 [<c0107890>] native_sched_clock+0x88/0x99
 [<c011dae6>] sched_rt_period_timer+0x0/0x1fc
 [<c0136dda>] run_hrtimer_pending+0x54/0xe5
 [<c011dae6>] sched_rt_period_timer+0x0/0x1fc
 [<c0128afb>] __do_softirq+0x7b/0xef
 [<c0128ba6>] do_softirq+0x37/0x4d
 [<c0128c12>] ksoftirqd+0x56/0xc5
 [<c0128bbc>] ksoftirqd+0x0/0xc5
 [<c0134649>] kthread+0x38/0x5d
 [<c0134611>] kthread+0x0/0x5d
 [<c0104477>] kernel_thread_helper+0x7/0x10
 =======================

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-11 10:46:42 +01:00
Thomas Gleixner
268a3dcfea Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2
Conflicts:

	kernel/time/tick-sched.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-22 09:48:06 +02:00
Thomas Gleixner
643bdf68f9 hrtimers: simplify hrtimer_peek_ahead_timers()
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-20 13:38:11 +02:00
Thomas Gleixner
e1dd7bc585 hrtimers: fix docbook comments
hrtimer_start() and hrtimer_start_range_ns() handle relative and
absolute timers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-20 13:33:36 +02:00
Thomas Gleixner
c465a76af6 Merge branches 'timers/clocksource', 'timers/hrtimers', 'timers/nohz', 'timers/ntp', 'timers/posixtimers' and 'timers/debug' into v28-timers-for-linus 2008-10-20 13:14:06 +02:00
Arjan van de Ven
651dab4264 Merge commit 'linus/master' into merge-linus
Conflicts:

	arch/x86/kvm/i8254.c
2008-10-17 09:20:26 -07:00
Arjan van de Ven
dc4304f7de rangetimers: fix the bug reported by Ingo for real
and please hand me a brown paper bag

(thanks to Thomas for pointing out this very obvious bug)

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-10-13 11:08:34 -04:00
Arjan van de Ven
030aebd2e4 rangetimer: fix BUG_ON reported by Ingo
There's a small race/chance that, while hrtimers are enabled globally,
they're later not enabled when we're calling the hrtimer_interrupt() function,
which then BUG_ON()'s for that. This patch closes that race/gap.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-10-11 12:25:45 -07:00
Thomas Gleixner
ccc7dadf73 hrtimer: prevent migration of per CPU hrtimers
Impact: per CPU hrtimers can be migrated from a dead CPU

The hrtimer code has no knowledge about per CPU timers, but we need to
prevent the migration of such timers and warn when such a timer is
active at migration time.

Explicitely mark the timers as per CPU and use a more understandable
mode descriptor for the interrupts safe unlocked callback mode, which
is used by hrtimer_sleeper and the scheduler code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:14 +02:00
Thomas Gleixner
b00c1a99e7 hrtimer: mark migration state
Impact: during migration active hrtimers can be seen as inactive

The migration code removes the hrtimers from the queues of the dead
CPU and sets the state temporary to INACTIVE. The enqueue code sets it
to ACTIVE/PENDING again.

Prevent that the wrong state can be seen by using a separate migration
state bit.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:14 +02:00
Thomas Gleixner
41e1022eae hrtimer: fix migration of CB_IRQSAFE_NO_SOFTIRQ hrtimers
Impact: Stale timers after a CPU went offline.

commit 37bb6cb409
       hrtimer: unlock hrtimer_wakeup

changed the hrtimer sleeper callback mode to CB_IRQSAFE_NO_SOFTIRQ due
to locking problems. A result of this change is that when enqueue is
called for an already expired hrtimer the callback function is not
longer called directly from the enqueue code. The normal callers have
been fixed in the code, but the migration code which moves hrtimers
from a dead CPU to a live CPU was not made aware of this.

This can be fixed by checking the timer state after the call to
enqueue in the migration code.


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:14 +02:00
Thomas Gleixner
7659e34967 hrtimer: migrate pending list on cpu offline
Impact: hrtimers which are on the pending list are not migrated at cpu
	offline and can be stale forever

Add the pending list migration when CONFIG_HIGH_RES_TIMERS is enabled

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:13 +02:00
Mark McLoughlin
d7cfb60c5c hrtimer: remove hrtimer_clock_base::get_softirq_time()
Peter Zijlstra noticed this 8 months ago and I just noticed
it again.

hrtimer_clock_base::get_softirq_time() is currently unused
in the entire tree. In fact, looking at the logs, it appears
as if it was never used. Remove it.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-22 13:52:42 +02:00
Arjan van de Ven
2e94d1f71f hrtimer: peek at the timer queue just before going idle
As part of going idle, we already look at the time of the next timer event to determine
which C-state to select etc.

This patch adds functionality that causes the timers that are past their
soft expire time, to fire at this time, before we calculate the next wakeup
time. This functionality will thus avoid wakeups by running timers before
going idle rather than specially waking up for it.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-09-11 07:17:49 -07:00
Arjan van de Ven
3bd012060f hrtimer: make the nanosleep() syscall use the per process slack
This patch makes the nanosleep() system call use the per process
slack value; with this users are able to externally control existing
applications to reduce the wakeup rate.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-09-11 07:16:55 -07:00
Arjan van de Ven
da8f2e170e hrtimer: add a hrtimer_start_range() function
this patch adds a _range version of hrtimer_start() so that range timers
can be created; the hrtimer_start() function is just a wrapper around this.

In addition, hrtimer_start_expires() will now preserve existing ranges.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-09-07 10:58:01 -07:00
Arjan van de Ven
654c8e0b1c hrtimer: turn hrtimers into range timers
this patch turns hrtimers into range timers; they have 2 expire points
1) the soft expire point
2) the hard expire point

the kernel will do it's regular best effort attempt to get the timer run
at the hard expire point. However, if some other time fires after the soft
expire point, the kernel now has the freedom to fire this timer at this point,
and thus grouping the events and preventing a power-expensive wakeup in the
future.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-09-05 21:35:27 -07:00
Arjan van de Ven
cc584b213f hrtimer: convert kernel/* to the new hrtimer apis
In order to be able to do range hrtimers we need to use accessor functions
to the "expire" member of the hrtimer struct.
This patch converts kernel/* to these accessors.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-09-05 21:35:13 -07:00
Arjan van de Ven
7bb67439bf select: Introduce a hrtimeout function
This patch adds a schedule_hrtimeout() function, to be used by select() and
poll() in a later patch. This function works similar to schedule_timeout()
in most ways, but takes a timespec rather than jiffies.

With a lot of contributions/fixes from Thomas

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-05 21:34:53 -07:00
Oleg Nesterov
d82f0b0f6f migrate_timers: add comment, use spinlock_irq()
Add the comment to explain why the double lock in migrate_timers()
can't deadlock.

Change the code to use spinlock_irq() instead of local_irq_disable()
+ spin_lock().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-21 13:34:54 +02:00
Ingo Molnar
1a781a777b Merge branch 'generic-ipi' into generic-ipi-for-linus
Conflicts:

	arch/powerpc/Kconfig
	arch/s390/kernel/time.c
	arch/x86/kernel/apic_32.c
	arch/x86/kernel/cpu/perfctr-watchdog.c
	arch/x86/kernel/i8259_64.c
	arch/x86/kernel/ldt.c
	arch/x86/kernel/nmi_64.c
	arch/x86/kernel/smpboot.c
	arch/x86/xen/smp.c
	include/asm-x86/hw_irq_32.h
	include/asm-x86/hw_irq_64.h
	include/asm-x86/mach-default/irq_vectors.h
	include/asm-x86/mach-voyager/irq_vectors.h
	include/asm-x86/smp.h
	kernel/Makefile

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-15 21:55:59 +02:00
Linus Torvalds
da6e88f496 Merge branch 'timers/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: add PCI ID for 6300ESB force hpet
  x86: add another PCI ID for ICH6 force-hpet
  kernel-paramaters: document pmtmr= command line option
  acpi_pm clccksource: fix printk format warning
  nohz: don't stop idle tick if softirqs are pending.
  pmtmr: allow command line override of ioport
  nohz: reduce jiffies polling overhead
  hrtimer: Remove unused variables in ktime_divns()
  hrtimer: remove warning in hres_timers_resume
  posix-timers: print RT watchdog message
2008-07-15 10:39:57 -07:00
Linus Torvalds
85082fd7cb Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (241 commits)
  [ARM] 5171/1: ep93xx: fix compilation of modules using clocks
  [ARM] 5133/2: at91sam9g20 defconfig file
  [ARM] 5130/4: Support for the at91sam9g20
  [ARM] 5160/1: IOP3XX: gpio/gpiolib support
  [ARM] at91: Fix NAND FLASH timings for at91sam9x evaluation kits.
  [ARM] 5084/1: zylonite: Register AC97 device
  [ARM] 5085/2: PXA: Move AC97 over to the new central device declaration model
  [ARM] 5120/1: pxa: correct platform driver names for PXA25x and PXA27x UDC drivers
  [ARM] 5147/1: pxaficp_ir: drop pxa_gpio_mode calls, as pin setting
  [ARM] 5145/1: PXA2xx: provide api to control IrDA pins state
  [ARM] 5144/1: pxaficp_ir: cleanup includes
  [ARM] pxa: remove pxa_set_cken()
  [ARM] pxa: allow clk aliases
  [ARM] Feroceon: don't disable BPU on boot
  [ARM] Orion: LED support for HP mv2120
  [ARM] Orion: add RD88F5181L-FXO support
  [ARM] Orion: add RD88F5181L-GE support
  [ARM] Orion: add Netgear WNR854T support
  [ARM] s3c2410_defconfig: update for current build
  [ARM] Acer n30: Minor style and indentation fixes.
  ...
2008-07-14 16:06:58 -07:00
Linus Torvalds
666484f025 Merge branch 'core/softirq' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core/softirq' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  softirq: remove irqs_disabled warning from local_bh_enable
  softirq: remove initialization of static per-cpu variable
  Remove argument from open_softirq which is always NULL
2008-07-14 15:28:42 -07:00