linux-toradex.git/kernel/power/process.c, branch T30_LinuxImageV2.0Beta2_20130626

PM: wakelock: Don't dump unfrozen task list when aborting try_to_freeze_tasks after less than one second

2011-12-01T05:37:53+00:00

Change-Id: Ib2976e5b97a5ee4ec9abd4d4443584d9257d0941
Signed-off-by: Arve Hjønnevåg

PM: wakelock: Abort task freezing if a wake lock is held.

2011-12-01T05:37:52+00:00

Avoids a problem where the device sometimes hangs for 20 seconds
before the screen is turned on.

workqueue, freezer: unify spelling of 'freeze' + 'able' to 'freezable'

2011-02-16T16:48:59+00:00

There are two spellings in use for 'freeze' + 'able' - 'freezable' and
'freezeable'.  The former is the more prominent one.  The latter is
mostly used by workqueue and in a few other odd places.  Unify the
spelling to 'freezable'.

Signed-off-by: Tejun Heo 
Reported-by: Alan Stern 
Acked-by: "Rafael J. Wysocki" 
Acked-by: Greg Kroah-Hartman 
Acked-by: Dmitry Torokhov 
Cc: David Woodhouse 
Cc: Alex Dubov 
Cc: "David S. Miller" 
Cc: Steven Whitehouse

PM / Wakeup: Replace pm_check_wakeup_events() with pm_wakeup_pending()

2010-12-24T14:02:42+00:00

To avoid confusion with the meaning and return value of
pm_check_wakeup_events() replace it with pm_wakeup_pending() that
will work the other way around (ie. return true when system-wide
power transition should be aborted).

Signed-off-by: Rafael J. Wysocki

Freezer: Fix a race during freezing of TASK_STOPPED tasks

2010-12-24T14:02:40+00:00

After calling freeze_task(), try_to_freeze_tasks() see whether the
task is stopped or traced and if so, considers it to be frozen;
however, nothing guarantees that either the task being frozen sees
TIF_FREEZE or the freezer sees TASK_STOPPED -> TASK_RUNNING
transition.  The task being frozen may wake up and not see TIF_FREEZE
while the freezer fails to notice the transition and believes the task
is still stopped.

This patch fixes the race by making freeze_task() always go through
fake_signal_wake_up() for applicable tasks.  The function goes through
the target task's scheduler lock and thus guarantees that either the
target sees TIF_FREEZE or try_to_freeze_task() sees TASK_RUNNING.

Signed-off-by: Tejun Heo 
Signed-off-by: Rafael J. Wysocki

PM: Allow wakeup events to abort freezing of tasks

2010-10-16T23:57:49+00:00

If there is a wakeup event during the freezing of tasks, suspend or
hibernation will fail anyway.  Since try_to_freeze_tasks() can take
up to 20 seconds to complete or fail, aborting it as soon as a wakeup
event is detected improves the worst case wakeup latency.

Based on a patch from Arve Hjønnevåg.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Pavel Machek

workqueue: reimplement workqueue freeze using max_active

2010-06-29T08:07:12+00:00

Currently, workqueue freezing is implemented by marking the worker
freezeable and calling try_to_freeze() from dispatch loop.
Reimplement it using cwq->limit so that the workqueue is frozen
instead of the worker.

* workqueue_struct->saved_max_active is added which stores the
  specified max_active on initialization.

* On freeze, all cwq->max_active's are quenched to zero.  Freezing is
  complete when nr_active on all cwqs reach zero.

* On thaw, all cwq->max_active's are restored to wq->saved_max_active
  and the worklist is repopulated.

This new implementation allows having single shared pool of workers
per cpu.

Signed-off-by: Tejun Heo

Freezer: Fix buggy resume test for tasks frozen with cgroup freezer

2010-03-26T22:51:44+00:00

When the cgroup freezer is used to freeze tasks we do not want to thaw
those tasks during resume. Currently we test the cgroup freezer
state of the resuming tasks to see if the cgroup is FROZEN.  If so
then we don't thaw the task. However, the FREEZING state also indicates
that the task should remain frozen.

This also avoids a problem pointed out by Oren Ladaan: the freezer state
transition from FREEZING to FROZEN is updated lazily when userspace reads
or writes the freezer.state file in the cgroup filesystem. This means that
resume will thaw tasks in cgroups which should be in the FROZEN state if
there is no read/write of the freezer.state file to trigger this
transition before suspend.

NOTE: Another "simple" solution would be to always update the cgroup
freezer state during resume. However it's a bad choice for several reasons:
Updating the cgroup freezer state is somewhat expensive because it requires
walking all the tasks in the cgroup and checking if they are each frozen.
Worse, this could easily make resume run in N^2 time where N is the number
of tasks in the cgroup. Finally, updating the freezer state from this code
path requires trickier locking because of the way locks must be ordered.

Instead of updating the freezer state we rely on the fact that lazy
updates only manage the transition from FREEZING to FROZEN. We know that
a cgroup with the FREEZING state may actually be FROZEN so test for that
state too. This makes sense in the resume path even for partially-frozen
cgroups -- those that really are FREEZING but not FROZEN.

Reported-by: Oren Ladaan 
Signed-off-by: Matt Helsley 
Cc: stable@kernel.org
Signed-off-by: Rafael J. Wysocki

Freezer: Only show the state of tasks refusing to freeze

2010-03-26T22:51:13+00:00

show_state will dump all tasks state, so if freezer failed to freeze
any task, kernel will dump all tasks state and flood the dmesg log.
This patch makes freezer only show state of tasks refusing to freeze.

Signed-off-by: Xiaotian Feng 
Acked-by: Pavel Machek 
Acked-by: David Rientjes 
Signed-off-by: Rafael J. Wysocki

PM / freezer: Don't get over-anxious while waiting

2009-10-28T21:53:09+00:00

Freezing isn't exactly the most latency sensitive operation and
there's no reason to burn cpu cycles and power waiting for it to
complete.  msleep(10) instead of yield().  This should improve
reliability of emergency hibernation.

[rjw: Modified the comment next to the msleep(10).]

Signed-off-by: Tejun Heo 
Signed-off-by: Rafael J. Wysocki