linux-stable.git/include/linux/cpu.h, branch v3.12.72

hotplug: Make register and unregister notifier API symmetric

2017-01-26T16:22:20+00:00

commit 777c6e0daebb3fcefbbd6f620410a946b07ef6d0 upstream.

Yu Zhao has noticed that __unregister_cpu_notifier only unregisters its
notifiers when HOTPLUG_CPU=y while the registration might succeed even
when HOTPLUG_CPU=n if MODULE is enabled. This means that e.g. zswap
might keep a stale notifier on the list on the manual clean up during
the pool tear down and thus corrupt the list. Resulting in the following

[  144.964346] BUG: unable to handle kernel paging request at ffff880658a2be78
[  144.971337] IP: [] raw_notifier_chain_register+0x1b/0x40

[  145.122628] Call Trace:
[  145.125086]  [] __register_cpu_notifier+0x18/0x20
[  145.131350]  [] zswap_pool_create+0x273/0x400
[  145.137268]  [] __zswap_param_set+0x1fc/0x300
[  145.143188]  [] ? trace_hardirqs_on+0xd/0x10
[  145.149018]  [] ? kernel_param_lock+0x28/0x30
[  145.154940]  [] ? __might_fault+0x4f/0xa0
[  145.160511]  [] zswap_compressor_param_set+0x17/0x20
[  145.167035]  [] param_attr_store+0x5c/0xb0
[  145.172694]  [] module_attr_store+0x1d/0x30
[  145.178443]  [] sysfs_kf_write+0x4f/0x70
[  145.183925]  [] kernfs_fop_write+0x149/0x180
[  145.189761]  [] __vfs_write+0x18/0x40
[  145.194982]  [] vfs_write+0xb2/0x1a0
[  145.200122]  [] SyS_write+0x52/0xa0
[  145.205177]  [] entry_SYSCALL_64_fastpath+0x12/0x17

This can be even triggered manually by changing
/sys/module/zswap/parameters/compressor multiple times.

Fix this issue by making unregister APIs symmetric to the register so
there are no surprises.

[js] backport to 3.12

Fixes: 47e627bc8c9a ("[PATCH] hotplug: Allow modules to use the cpu hotplug notifiers even if !CONFIG_HOTPLUG_CPU")
Reported-and-tested-by: Yu Zhao 
Signed-off-by: Michal Hocko 
Cc: linux-mm@kvack.org
Cc: Andrew Morton 
Cc: Dan Streetman 
Link: http://lkml.kernel.org/r/20161207135438.4310-1-mhocko@kernel.org
Signed-off-by: Thomas Gleixner 
Signed-off-by: Jiri Slaby

Merge branch 'pm-cpufreq'

2013-08-26T23:44:40+00:00

* pm-cpufreq: (60 commits)
  cpufreq: pmac32-cpufreq: remove device tree parsing for cpu nodes
  cpufreq: pmac64-cpufreq: remove device tree parsing for cpu nodes
  cpufreq: maple-cpufreq: remove device tree parsing for cpu nodes
  cpufreq: arm_big_little: remove device tree parsing for cpu nodes
  cpufreq: kirkwood-cpufreq: remove device tree parsing for cpu nodes
  cpufreq: spear-cpufreq: remove device tree parsing for cpu nodes
  cpufreq: highbank-cpufreq: remove device tree parsing for cpu nodes
  cpufreq: cpufreq-cpu0: remove device tree parsing for cpu nodes
  cpufreq: imx6q-cpufreq: remove device tree parsing for cpu nodes
  drivers/bus: arm-cci: avoid parsing DT for cpu device nodes
  ARM: mvebu: remove device tree parsing for cpu nodes
  ARM: topology: remove hwid/MPIDR dependency from cpu_capacity
  of/device: add helper to get cpu device node from logical cpu index
  driver/core: cpu: initialize of_node in cpu's device struture
  ARM: DT/kernel: define ARM specific arch_match_cpu_phys_id
  of: move of_get_cpu_node implementation to DT core library
  powerpc: refactor of_get_cpu_node to support other architectures
  openrisc: remove undefined of_get_cpu_node declaration
  microblaze: remove undefined of_get_cpu_node declaration
  cpufreq: fix bad unlock balance on !CONFIG_SMP
  ...

of: move of_get_cpu_node implementation to DT core library

2013-08-21T09:24:44+00:00

This patch moves the generalized implementation of of_get_cpu_node from
PowerPC to DT core library, thereby adding support for retrieving cpu
node for a given logical cpu index on any architecture.

The CPU subsystem can now use this function to assign of_node in the
cpu device while registering CPUs.

It is recommended to use these helper function only in pre-SMP/early
initialisation stages to retrieve CPU device node pointers in logical
ordering. Once the cpu devices are registered, it can be retrieved easily
from cpu device of_node which avoids unnecessary parsing and matching.

Cc: Benjamin Herrenschmidt 
Cc: Grant Likely 
Acked-by: Rob Herring 
Signed-off-by: Sudeep KarkadaNagesha

ACPI / processor: Acquire writer lock to update CPU maps

2013-08-13T10:20:16+00:00

CPU system maps are protected with reader/writer locks.  The reader
lock, get_online_cpus(), assures that the maps are not updated while
holding the lock.  The writer lock, cpu_hotplug_begin(), is used to
udpate the cpu maps along with cpu_maps_update_begin().

However, the ACPI processor handler updates the cpu maps without
holding the the writer lock.

acpi_map_lsapic() is called from acpi_processor_hotadd_init() to
update cpu_possible_mask and cpu_present_mask.  acpi_unmap_lsapic()
is called from acpi_processor_remove() to update cpu_possible_mask.
Currently, they are either unprotected or protected with the reader
lock, which is not correct.

For example, the get_online_cpus() below is supposed to assure that
cpu_possible_mask is not changed while the code is iterating with
for_each_possible_cpu().

        get_online_cpus();
        for_each_possible_cpu(cpu) {
		:
        }
        put_online_cpus();

However, this lock has no protection with CPU hotplug since the ACPI
processor handler does not use the writer lock when it updates
cpu_possible_mask.  The reader lock does not serialize within the
readers.

This patch protects them with the writer lock with cpu_hotplug_begin()
along with cpu_maps_update_begin(), which must be held before calling
cpu_hotplug_begin().  It also protects arch_register_cpu() /
arch_unregister_cpu(), which creates / deletes a sysfs cpu device
interface.  For this purpose it changes cpu_hotplug_begin() and
cpu_hotplug_done() to global and exports them in cpu.h.

Signed-off-by: Toshi Kani 
Signed-off-by: Rafael J. Wysocki

kernel: delete __cpuinit usage from all core kernel files

2013-07-14T23:36:59+00:00

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the uses of the __cpuinit macros from C files in
the core kernel directories (kernel, init, lib, mm, and include)
that don't really have a specific maintainer.

[1] https://lkml.org/lkml/2013/5/20/589

Signed-off-by: Paul Gortmaker

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2013-07-04T18:40:58+00:00

Pull trivial tree updates from Jiri Kosina:
 "The usual stuff from trivial tree"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (34 commits)
  treewide: relase -> release
  Documentation/cgroups/memory.txt: fix stat file documentation
  sysctl/net.txt: delete reference to obsolete 2.4.x kernel
  spinlock_api_smp.h: fix preprocessor comments
  treewide: Fix typo in printk
  doc: device tree: clarify stuff in usage-model.txt.
  open firmware: "/aliasas" -> "/aliases"
  md: bcache: Fixed a typo with the word 'arithmetic'
  irq/generic-chip: fix a few kernel-doc entries
  frv: Convert use of typedef ctl_table to struct ctl_table
  sgi: xpc: Convert use of typedef ctl_table to struct ctl_table
  doc: clk: Fix incorrect wording
  Documentation/arm/IXP4xx fix a typo
  Documentation/networking/ieee802154 fix a typo
  Documentation/DocBook/media/v4l fix a typo
  Documentation/video4linux/si476x.txt fix a typo
  Documentation/virtual/kvm/api.txt fix a typo
  Documentation/early-userspace/README fix a typo
  Documentation/video4linux/soc-camera.txt fix a typo
  lguest: fix CONFIG_PAE -> CONFIG_x86_PAE in comment
  ...

CPU hotplug: provide a generic helper to disable/enable CPU hotplug

2013-06-12T23:29:44+00:00

There are instances in the kernel where we would like to disable CPU
hotplug (from sysfs) during some important operation.  Today the freezer
code depends on this and the code to do it was kinda tailor-made for
that.

Restructure the code and make it generic enough to be useful for other
usecases too.

Signed-off-by: Srivatsa S. Bhat 
Signed-off-by: Robin Holt 
Cc: H. Peter Anvin 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Russ Anderson 
Cc: Robin Holt 
Cc: Russell King 
Cc: Guan Xuetao 
Cc: Shawn Guo 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

include/linux/cpu.h: Update comments to reflect reality

2013-05-28T10:02:11+00:00

Two minor changes to comments:

* Remove reference to drivers/base/sys.c, removed in 0a962657.
* CPUs are now exported by sysfs via devices/system/cpu.

Signed-off-by: Robert P. J. Day 
Signed-off-by: Jiri Kosina

idle: Implement generic idle function

2013-04-08T15:39:23+00:00

All idle functions in arch/* are more or less the same, plus minus a
few bugs and extra instrumentation, tickless support and other
optional items.

Implement a generic idle function which resembles the functionality
found in arch/. Provide weak arch_cpu_idle_* functions which can be
overridden by the architecture code if needed.

Signed-off-by: Thomas Gleixner 
Cc: Linus Torvalds 
Cc: Rusty Russell 
Cc: Paul McKenney 
Cc: Peter Zijlstra 
Reviewed-by: Cc: Srivatsa S. Bhat 
Cc: Magnus Damm 
Link: http://lkml.kernel.org/r/20130321215233.646635455@linutronix.de
Signed-off-by: Thomas Gleixner

idle: Provide a generic entry point for the idle code

2013-04-08T15:39:23+00:00

For now this calls cpu_idle(), but in the long run we want to move the
cpu bringup code to the core and therefor we add a state argument.

Signed-off-by: Thomas Gleixner 
Cc: Linus Torvalds 
Cc: Rusty Russell 
Cc: Paul McKenney 
Cc: Peter Zijlstra 
Reviewed-by: Cc: Srivatsa S. Bhat 
Cc: Magnus Damm 
Link: http://lkml.kernel.org/r/20130321215233.583190032@linutronix.de
Signed-off-by: Thomas Gleixner