linux-toradex.git/drivers/cpuidle, branch v3.12.43

cpuidle: Check for dev before deregistering it.

2013-12-12T06:37:54+00:00

commit 813e8e3d6aaa0b511126cce15c16a931afffe768 upstream.

If not, we could end up in the unfortunate situation where
we dereference a NULL pointer b/c we have cpuidle disabled.

This is the case when booting under Xen (which uses the
ACPI P/C states but disables the CPU idle driver) - and can
be easily reproduced when booting with cpuidle.off=1.

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [] cpuidle_unregister_device+0x2a/0x90
.. snip..
Call Trace:
 [] acpi_processor_power_exit+0x3c/0x5c
 [] acpi_processor_stop+0x61/0xb6
 [] __device_release_driver+0fffff81421653>] device_release_driver+0x23/0x30
 [] bus_remove_device+0x108/0x180
 [] device_del+0x129/0x1c0
 [] ? unregister_xenbus_watch+0x1f0/0x1f0
 [] device_unregister+0x1e/0x60
 [] unregister_cpu+0x39/0x60
 [] arch_unregister_cpu+0x23/0x30
 [] handle_vcpu_hotplug_event+0xc1/0xe0
 [] xenwatch_thread+0x45/0x120
 [] ? abort_exclusive_wait+0xb0/0xb0
 [] kthread+0xd2/0xf0
 [] ? kthread_create_on_node+0x180/0x180
 [] ret_from_fork+0x7c/0xb0
 [] ? kthread_create_on_node+0x180/0x180

This problem also appears in 3.12 and could be a candidate for backport.

Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'pm+acpi-fixes-3.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2013-09-12T18:22:45+00:00

Pull ACPI and power management fixes from Rafael Wysocki:
 "All of these commits are fixes that have emerged recently and some of
  them fix bugs introduced during this merge window.

  Specifics:

   1) ACPI-based PCI hotplug (ACPIPHP) fixes related to spurious events

      After the recent ACPIPHP changes we've seen some interesting
      breakage on a system that triggers device check notifications
      during boot for non-existing devices.  Although those
      notifications are really spurious, we should be able to deal with
      them nevertheless and that shouldn't introduce too much overhead.
      Four commits to make that work properly.

   2) Memory hotplug and hibernation mutual exclusion rework

      This was maent to be a cleanup, but it happens to fix a classical
      ABBA deadlock between system suspend/hibernation and ACPI memory
      hotplug which is possible if they are started roughly at the same
      time.  Three commits rework memory hotplug so that it doesn't
      acquire pm_mutex and make hibernation use device_hotplug_lock
      which prevents it from racing with memory hotplug.

   3) ACPI Intel LPSS (Low-Power Subsystem) driver crash fix

      The ACPI LPSS driver crashes during boot on Apple Macbook Air with
      Haswell that has slightly unusual BIOS configuration in which one
      of the LPSS device's _CRS method doesn't return all of the
      information expected by the driver.  Fix from Mika Westerberg, for
      stable.

   4) ACPICA fix related to Store->ArgX operation

      AML interpreter fix for obscure breakage that causes AML to be
      executed incorrectly on some machines (observed in practice).
      From Bob Moore.

   5) ACPI core fix for PCI ACPI device objects lookup

      There still are cases in which there is more than one ACPI device
      object matching a given PCI device and we don't choose the one
      that the BIOS expects us to choose, so this makes the lookup take
      more criteria into account in those cases.

   6) Fix to prevent cpuidle from crashing in some rare cases

      If the result of cpuidle_get_driver() is NULL, which can happen on
      some systems, cpuidle_driver_ref() will crash trying to use that
      pointer and the Daniel Fu's fix prevents that from happening.

   7) cpufreq fixes related to CPU hotplug

      Stephen Boyd reported a number of concurrency problems with
      cpufreq related to CPU hotplug which are addressed by a series of
      fixes from Srivatsa S Bhat and Viresh Kumar.

   8) cpufreq fix for time conversion in time_in_state attribute

      Time conversion carried out by cpufreq when user space attempts to
      read /sys/devices/system/cpu/cpu*/cpufreq/stats/time_in_state
      won't work correcty if cputime_t doesn't map directly to jiffies.
      Fix from Andreas Schwab.

   9) Revert of a troublesome cpufreq commit

      Commit 7c30ed5 (cpufreq: make sure frequency transitions are
      serialized) was intended to address some known concurrency
      problems in cpufreq related to the ordering of transitions, but
      unfortunately it introduced several problems of its own, so I
      decided to revert it now and address the original problems later
      in a more robust way.

  10) Intel Haswell CPU models for intel_pstate from Nell Hardcastle.

  11) cpufreq fixes related to system suspend/resume

      The recent cpufreq changes that made it preserve CPU sysfs
      attributes over suspend/resume cycles introduced a possible NULL
      pointer dereference that caused it to crash during the second
      attempt to suspend.  Three commits from Srivatsa S Bhat fix that
      problem and a couple of related issues.

  12) cpufreq locking fix

      cpufreq_policy_restore() should acquire the lock for reading, but
      it acquires it for writing.  Fix from Lan Tianyu"

* tag 'pm+acpi-fixes-3.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (25 commits)
  cpufreq: Acquire the lock in cpufreq_policy_restore() for reading
  cpufreq: Prevent problems in update_policy_cpu() if last_cpu == new_cpu
  cpufreq: Restructure if/else block to avoid unintended behavior
  cpufreq: Fix crash in cpufreq-stats during suspend/resume
  intel_pstate: Add Haswell CPU models
  Revert "cpufreq: make sure frequency transitions are serialized"
  cpufreq: Use signed type for 'ret' variable, to store negative error values
  cpufreq: Remove temporary fix for race between CPU hotplug and sysfs-writes
  cpufreq: Synchronize the cpufreq store_*() routines with CPU hotplug
  cpufreq: Invoke __cpufreq_remove_dev_finish() after releasing cpu_hotplug.lock
  cpufreq: Split __cpufreq_remove_dev() into two parts
  cpufreq: Fix wrong time unit conversion
  cpufreq: serialize calls to __cpufreq_governor()
  cpufreq: don't allow governor limits to be changed when it is disabled
  ACPI / bind: Prefer device objects with _STA to those without it
  ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device checks
  ACPI / hotplug / PCI: Use _OST to notify firmware about notify status
  ACPI / hotplug / PCI: Avoid doing too much for spurious notifies
  ACPICA: Fix for a Store->ArgX when ArgX contains a reference to a field.
  ACPI / hotplug / PCI: Don't trim devices before scanning the namespace
  ...

Merge tag 'drivers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

2013-09-09T23:08:13+00:00

Pull ARM SoC driver update from Kevin Hilman:
 "This contains the ARM SoC related driver updates for v3.12.  The only
  thing this cycle are core PM updates and CPUidle support for ARM's TC2
  big.LITTLE development platform"

* tag 'drivers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  cpuidle: big.LITTLE: vexpress-TC2 CPU idle driver
  ARM: vexpress: tc2: disable GIC CPU IF in tc2_pm_suspend
  drivers: irq-chip: irq-gic: introduce gic_cpu_if_down()

cpuidle: Check the result of cpuidle_get_driver() against NULL

2013-08-30T19:53:41+00:00

If the current CPU has no cpuidle driver, drv will be NULL in
cpuidle_driver_ref().  Check if that is the case before trying
to bump up the driver's refcount to prevent the kernel from
crashing.

[rjw: Subject and changelog]
Signed-off-by: Daniel Fu 
Signed-off-by: Rafael J. Wysocki

cpuidle: coupled: fix race condition between pokes and safe state

2013-08-29T20:15:34+00:00

The coupled cpuidle waiting loop clears pending pokes before
entering the safe state.  If a poke arrives just before the
pokes are cleared, but after the while loop condition checks,
the poke will be lost and the cpu will stay in the safe state
until another interrupt arrives.  This may cause the cpu that
sent the poke to spin in the ready loop with interrupts off
until another cpu receives an interrupt, and if no other cpus
have interrupts routed to them it can spin forever.

Change the return value of cpuidle_coupled_clear_pokes to
return if a poke was cleared, and move the need_resched()
checks into the callers.  In the waiting loop, if
a poke was cleared restart the loop to repeat the while
condition checks.

Reported-by: Neil Zhang 
Signed-off-by: Colin Cross 
Cc: 3.6+  # 3.6+
Signed-off-by: Rafael J. Wysocki

cpuidle: coupled: abort idle if pokes are pending

2013-08-29T20:15:04+00:00

Joseph Lo  reported a lockup on Tegra20 caused
by a race condition in coupled cpuidle.  When two or more cpus
enter idle at the same time, the first cpus to arrive may go to the
ready loop without processing pending pokes from the last cpu to
arrive.

This patch adds a check for pending pokes once all cpus have been
synchronized in the ready loop and resets the coupled state and
retries if any cpus failed to handle their pending poke.

Retrying on all cpus may trigger the same issue again, so this patch
also adds a check to ensure that each cpu has received at least one
poke between when it enters the waiting loop and when it moves on to
the ready loop.

Reported-and-tested-by: Joseph Lo 
Tested-by: Stephen Warren 
Signed-off-by: Colin Cross 
Cc: 3.6+  # 3.6+
Signed-off-by: Rafael J. Wysocki

cpuidle: coupled: disable interrupts after entering safe state

2013-08-29T20:11:38+00:00

Calling cpuidle_enter_state is expected to return with interrupts
enabled, but interrupts must be disabled before starting the
ready loop synchronization stage.  Call local_irq_disable after
each call to cpuidle_enter_state for the safe state.

Tested-by: Stephen Warren 
Signed-off-by: Colin Cross 
Signed-off-by: Rafael J. Wysocki

Merge branch 'cpuidle/biglittle' into next/drivers

2013-08-28T18:29:18+00:00

From Lorenzo Pieralisi:
This patch series contains:

- GIC driver update to add a method to disable the GIC CPU IF
- TC2 MCPM update to add GIC CPU disabling to suspend method
- TC2 CPU idle big.LITTLE driver

* cpuidle/biglittle:
  cpuidle: big.LITTLE: vexpress-TC2 CPU idle driver
  ARM: vexpress: tc2: disable GIC CPU IF in tc2_pm_suspend
  drivers: irq-chip: irq-gic: introduce gic_cpu_if_down()
  ARM: vexpress/TC2: implement PM suspend method
  ARM: vexpress/TC2: basic PM support
  ARM: vexpress: Add SCC to V2P-CA15_A7's device tree
  ARM: vexpress/TC2: add Serial Power Controller (SPC) support
  ARM: vexpress/dcscb: fix cache disabling sequences

Signed-off-by: Olof Johansson

cpuidle: big.LITTLE: vexpress-TC2 CPU idle driver

2013-08-28T18:28:51+00:00

The big.LITTLE architecture is composed of two clusters of cpus. One cluster
contains less powerful but more energy efficient processors and the other
cluster groups the powerful but energy-intensive cpus.

The TC2 testchip implements two clusters of CPUs (A7 and A15 clusters in
a big.LITTLE configuration) connected through a CCI interconnect that manages
coherency of their respective L2 caches and intercluster distributed
virtual memory messages (DVM).

TC2 testchip integrates a power controller that manages cores resets, wake-up
IRQs and cluster low-power states. Power states are managed at cluster
level, which means that voltage is removed from a cluster iff all cores
in a cluster are in a wfi state. Single cores can enter a reset state
which is identical to wfi in terms of power consumption but simplifies the
way cluster states are entered.

This patch provides a multiple driver CPU idle implementation for TC2
which paves the way for a generic big.LITTLE idle driver for all
upcoming big.LITTLE based systems on chip.

The driver relies on the MCPM infrastructure to coordinate and manage
core power states; in particular MCPM allows to suspend specific cores
and hides the CPUs coordination required to shut-down clusters of CPUs.

Power down sequences for the respective clusters are implemented in the
MCPM TC2 backend, with all code needed to clean caches and exit coherency.

The multiple driver CPU idle infrastructure allows to define different
C-states for big and little cores, determined at boot by checking the
part id of the possible CPUs and initializing the respective logical
masks in the big and little drivers.

Current big.little systems are composed of A7 and A15 clusters, as
implemented in TC2, but in the future that may change and the driver
will have evolve to retrieve what is a 'big' cpu and what is a 'little'
cpu in order to build the correct topology.

Cc: Kevin Hilman 
Cc: Amit Kucheria 
Cc: Olof Johansson 
Cc: Nicolas Pitre 
Cc: Rafael J. Wysocki 
Signed-off-by: Daniel Lezcano 
Signed-off-by: Lorenzo Pieralisi 
Signed-off-by: Olof Johansson

cpuidle: Change struct menu_device field types

2013-08-22T22:24:16+00:00

Field predicted_us value can never exceed expected_us value, but it has
a potentially larger type. As there is no need for additional 32 bits of
zeroes on 32 bit plaforms, change the type of predicted_us to match the
type of expected_us.

Field correction_factor is used to store a value that cannot exceed the
product of RESOLUTION and DECAY (default 1024*8 = 8192). The constants
cannot in practice be incremented to such values, that they'd overflow
unsigned int even on 32 bit systems, so the type is changed to avoid
unnecessary 64 bit arithmetic on 32 bit systems.

One multiplication of (now) 32 bit values needs an added cast to avoid
truncation of the result and has been added.

In order to avoid another multiplication from 32 bit domain to 64 bit
domain, the new correction_factor calculation has been changed from
new = old * (DECAY-1) / DECAY
to
new = old - old / DECAY,
which with infinite precision would yeild exactly the same result, but
now changes the direction of rounding. The impact is not significant as
the maximum accumulated difference cannot exceed the value of DECAY,
which is relatively small compared to product of RESOLUTION and DECAY
(8 / 8192).

Signed-off-by: Tuukka Tikkanen 
Signed-off-by: Rafael J. Wysocki