linux-toradex.git/kernel/timer.c, branch v3.2.9-rt16 Linux kernel for Apalis and Colibri modules timer: Fix hotplug for -rt 2012-03-06T16:18:03+00:00 Steven Rostedt rostedt@goodmis.org 2012-03-01T18:55:28+00:00 c0fc248e5b9df595079b500246b3bd2f811db90d Revert the RT patch: Author: Ingo Molnar <mingo@elte.hu> Date: Fri Jul 3 08:30:32 2009 -0500 timers: fix timer hotplug on -rt Here we are in the CPU_DEAD notifier, and we must not sleep nor enable interrupts. There's no problem with sleeping in this notifier. But the get_cpu_var() had to be converted to a get_local_var(). Replace the previous fix with the get_local_var() convert. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Carsten Emde <C.Emde@osadl.org> Cc: John Kacur <jkacur@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Clark Williams <clark.williams@gmail.com> Cc: stable-rt@vger.kernel.org Link: http://lkml.kernel.org/r/20120301190344.948157137@goodmis.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Revert the RT patch:
    Author: Ingo Molnar <mingo@elte.hu>
    Date:   Fri Jul 3 08:30:32 2009 -0500
    timers: fix timer hotplug on -rt

    Here we are in the CPU_DEAD notifier, and we must not sleep nor
    enable interrupts.

There's no problem with sleeping in this notifier.

But the get_cpu_var() had to be converted to a get_local_var().

Replace the previous fix with the get_local_var() convert.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Carsten Emde <C.Emde@osadl.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Clark Williams <clark.williams@gmail.com>
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/20120301190344.948157137@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
x86-no-perf-irq-work-rt.patch 2012-03-06T16:17:59+00:00 Thomas Gleixner tglx@linutronix.de 2011-07-13T12:05:05+00:00 344f7abd61871d1ac393105e6be35f332ff3368f Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timer-handle-idle-trylock-in-get-next-timer-irq.patch 2012-03-06T16:17:55+00:00 Thomas Gleixner tglx@linutronix.de 2011-07-17T20:08:38+00:00 4f42cd87c827e4f544cb995f15eb3dcf07332ae7 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timers: Avoid the switch timers base set to NULL trick on RT 2012-03-06T16:17:46+00:00 Thomas Gleixner tglx@linutronix.de 2011-07-21T13:23:39+00:00 06b9d3b8771ae1b8ede63542a49f8ea5d9aceb95 On RT that code is preemptible, so we cannot assign NULL to timers base as a preempter would spin forever in lock_timer_base(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
On RT that code is preemptible, so we cannot assign NULL to timers
base as a preempter would spin forever in lock_timer_base().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timer: delay waking softirqs from the jiffy tick 2012-03-06T16:17:46+00:00 Peter Zijlstra peterz@infradead.org 2009-08-21T09:56:45+00:00 ca466f4e7f2203d224488d5cc0b1282c04cff287 People were complaining about broken balancing with the recent -rt series. A look at /proc/sched_debug yielded: cpu#0, 2393.874 MHz .nr_running : 0 .load : 0 .cpu_load[0] : 177522 .cpu_load[1] : 177522 .cpu_load[2] : 177522 .cpu_load[3] : 177522 .cpu_load[4] : 177522 cpu#1, 2393.874 MHz .nr_running : 4 .load : 4096 .cpu_load[0] : 181618 .cpu_load[1] : 180850 .cpu_load[2] : 180274 .cpu_load[3] : 179938 .cpu_load[4] : 179758 Which indicated the cpu_load computation was hosed, the 177522 value indicates that there is one RT task runnable. Initially I thought the old problem of calculating the cpu_load from a softirq had re-surfaced, however looking at the code shows its being done from scheduler_tick(). [ we really should fix this RT/cfs interaction some day... ] A few trace_printk()s later: sirq-timer/1-19 [001] 174.289744: 19: 50:S ==> [001] 0:140:R <idle> <idle>-0 [001] 174.290724: enqueue_task_rt: adding task: 19/sirq-timer/1 with load: 177522 <idle>-0 [001] 174.290725: 0:140:R + [001] 19: 50:S sirq-timer/1 <idle>-0 [001] 174.290730: scheduler_tick: current load: 177522 <idle>-0 [001] 174.290732: scheduler_tick: current: 0/swapper <idle>-0 [001] 174.290736: 0:140:R ==> [001] 19: 50:R sirq-timer/1 sirq-timer/1-19 [001] 174.290741: dequeue_task_rt: removing task: 19/sirq-timer/1 with load: 177522 sirq-timer/1-19 [001] 174.290743: 19: 50:S ==> [001] 0:140:R <idle> We see that we always raise the timer softirq before doing the load calculation. Avoid this by re-ordering the scheduler_tick() call in update_process_times() to occur before we deal with timers. This lowers the load back to sanity and restores regular load-balancing behaviour. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
People were complaining about broken balancing with the recent -rt
series.

A look at /proc/sched_debug yielded:

cpu#0, 2393.874 MHz
  .nr_running                    : 0
  .load                          : 0
  .cpu_load[0]                   : 177522
  .cpu_load[1]                   : 177522
  .cpu_load[2]                   : 177522
  .cpu_load[3]                   : 177522
  .cpu_load[4]                   : 177522
cpu#1, 2393.874 MHz
  .nr_running                    : 4
  .load                          : 4096
  .cpu_load[0]                   : 181618
  .cpu_load[1]                   : 180850
  .cpu_load[2]                   : 180274
  .cpu_load[3]                   : 179938
  .cpu_load[4]                   : 179758

Which indicated the cpu_load computation was hosed, the 177522 value
indicates that there is one RT task runnable. Initially I thought the
old problem of calculating the cpu_load from a softirq had re-surfaced,
however looking at the code shows its being done from scheduler_tick().

[ we really should fix this RT/cfs interaction some day... ]

A few trace_printk()s later:

    sirq-timer/1-19    [001]   174.289744:     19: 50:S ==> [001]     0:140:R <idle>
          <idle>-0     [001]   174.290724: enqueue_task_rt: adding task: 19/sirq-timer/1 with load: 177522
          <idle>-0     [001]   174.290725:      0:140:R   + [001]    19: 50:S sirq-timer/1
          <idle>-0     [001]   174.290730: scheduler_tick: current load: 177522
          <idle>-0     [001]   174.290732: scheduler_tick: current: 0/swapper
          <idle>-0     [001]   174.290736:      0:140:R ==> [001]    19: 50:R sirq-timer/1
    sirq-timer/1-19    [001]   174.290741: dequeue_task_rt: removing task: 19/sirq-timer/1 with load: 177522
    sirq-timer/1-19    [001]   174.290743:     19: 50:S ==> [001]     0:140:R <idle>

We see that we always raise the timer softirq before doing the load
calculation. Avoid this by re-ordering the scheduler_tick() call in
update_process_times() to occur before we deal with timers.

This lowers the load back to sanity and restores regular load-balancing
behaviour.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timers: mov printk_tick to soft interrupt 2012-03-06T16:17:46+00:00 Thomas Gleixner tglx@linutronix.de 2009-07-03T13:44:30+00:00 a231f25304d5c7d7a0f877e26a65e3a933af73f3 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
timers: fix timer hotplug on -rt 2012-03-06T16:17:45+00:00 Ingo Molnar mingo@elte.hu 2009-07-03T13:30:32+00:00 fc4f544f49dae6ae25c3872800e6255d3a5a72b6 Here we are in the CPU_DEAD notifier, and we must not sleep nor enable interrupts. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Here we are in the CPU_DEAD notifier, and we must not sleep nor
enable interrupts.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timers: preempt-rt support 2012-03-06T16:17:45+00:00 Ingo Molnar mingo@elte.hu 2009-07-03T13:30:20+00:00 c4c59e547fb4ce05cb15c36483917b2e12460b52 Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timers: prepare for full preemption 2012-03-06T16:17:45+00:00 Ingo Molnar mingo@elte.hu 2009-07-03T13:29:34+00:00 a41d597001569da24bf575e9878449abc6a8ab35 When softirqs can be preempted we need to make sure that cancelling the timer from the active thread can not deadlock vs. a running timer callback. Add a waitqueue to resolve that. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
When softirqs can be preempted we need to make sure that cancelling
the timer from the active thread can not deadlock vs. a running timer
callback. Add a waitqueue to resolve that.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
sys_getppid: add missing rcu_dereference 2011-12-09T15:50:29+00:00 Mandeep Singh Baines msb@chromium.org 2011-12-08T22:34:44+00:00 031af165b1cd295ef04d2bfbcae9bc3cb9180735 In order to safely dereference current->real_parent inside an rcu_read_lock, we need an rcu_dereference. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
In order to safely dereference current->real_parent inside an
rcu_read_lock, we need an rcu_dereference.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>