nhu/kernel_a52xq
Watch
1
Fork
You've already forked kernel_a52xq
 0
mirror of https://github.com/a52xq-dev/kernel.git synced 2026-10-20 14:48:14 +07:00
Code Issues Projects Releases Wiki Activity
616,023 commits 1 branch 0 tags 1.6 GiB
Commit graph kernel_a52xq/include/linux/cpu.h
Message SHA1
workqueue: Convert to state machine callbacks 
Get rid of the prio ordering of the separate notifiers and use a proper state
callback pair.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153335.197083890@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Thomas Gleixner   authored and   Ingo Molnar   commited 2016-07-14 09:34:43 +02:00
7ee681b252
perf/core: Remove perf CPU notifier code 
All users converted to state machine callbacks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153335.115333381@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Thomas Gleixner   authored and   Ingo Molnar   commited 2016-07-14 09:34:42 +02:00
89ab9cb169
sched/hotplug: Move migration CPU_DYING to sched_cpu_dying() 
Remove the hotplug notifier and make it an explicit state.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160310120025.502222097@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-05-06 14:58:25 +02:00
f2785ddb53
sched/hotplug: Convert cpu_[in]active notifiers to state machine 
Now that we reduced everything into single notifiers, it's simple to move them
into the hotplug state machine space.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-05-06 14:58:24 +02:00
40190a78f8
sched: Consolidate the notifier maze 
We can maintain the ordering of the scheduler cpu hotplug functionality nicely
in one notifer. Get rid of the maze.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-05-06 14:58:23 +02:00
135fb3e197
rcu: Make CPU_DYING_IDLE an explicit call 
Make the RCU CPU_DYING_IDLE callback an explicit function call, so it gets
invoked at the proper place.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.870167933@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-03-01 20:36:58 +01:00
27d50c7eeb
cpu/hotplug: Make wait for dead cpu completion based 
Kill the busy spinning on the control side and just wait for the hotplugged
cpu to tell that it reached the dead state.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.776157858@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-03-01 20:36:58 +01:00
e69aab1311
cpu/hotplug: Unpark smpboot threads from the state machine 
Handle the smpboot threads in the state machine.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.295777684@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-03-01 20:36:56 +01:00
931ef16330
cpu/hotplug: Convert to a state machine for the control processor 
Move the split out steps into a callback array and let the cpu_up/down
code iterate through the array functions. For now most of the
callbacks are asymmetric to resemble the current hotplug maze.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182340.671816690@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-03-01 20:36:54 +01:00
cff7d378d3
cpu/hotplug: Restructure FROZEN state handling 
There are only a few callbacks which really care about FROZEN
vs. !FROZEN. No need to have extra states for this.

Publish the frozen state in an extra variable which is updated under
the hotplug lock and let the users interested deal with it w/o
imposing that extra state checks on everyone.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182340.334912357@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2016-03-01 20:36:53 +01:00
090e77c391
cpu: Remove try_get_online_cpus() 
Now that synchronize_sched_expedited() no longer uses it, there are
no users of try_get_online_cpus() in mainline.  This commit therefore
removes it.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

Paul E. McKenney   commited 2015-10-07 16:02:49 -07:00
02ef3c4a2a
include, lib: add __printf attributes to several function prototypes 
Using __printf attributes helps to detect several format string issues
at compile time (even though -Wformat-security is currently disabled in
Makefile).  For example it can detect when formatting a pointer as a
number, like the issue fixed in commit a3fa71c40f ("wl18xx: show
rx_frames_per_rates as an array as it really is"), or when the arguments
do not match the format string, c.f.  for example commit 5ce1aca814
("reiserfs: fix __RASSERT format string").

To prevent similar bugs in the future, add a __printf attribute to every
function prototype which needs one in include/linux/ and lib/.  These
functions were mostly found by using gcc's -Wsuggest-attribute=format
flag.

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Nicolas Iooss   authored and   Linus Torvalds   commited 2015-07-17 16:39:53 -07:00
8db1486065
cpu: Provide smpboot_thread_init() on !CONFIG_SMP kernels as well 
Now that we are using smpboot_thread_init() in init/main.c as well,
provide it for !CONFIG_SMP as well.

This addresses a !CONFIG_SMP build failure.

Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Ingo Molnar   commited 2015-04-13 10:19:30 +02:00
590ee7dbd5
cpu: Defer smpboot kthread unparking until CPU known to scheduler 
Currently, smpboot_unpark_threads() is invoked before the incoming CPU
has been added to the scheduler's runqueue structures.  This might
potentially cause the unparked kthread to run on the wrong CPU, since the
correct CPU isn't fully set up yet.

That causes a sporadic, hard to debug boot crash triggering on some
systems, reported by Borislav Petkov, and bisected down to:

  2a442c9c64 ("x86: Use common outgoing-CPU-notification code")

This patch places smpboot_unpark_threads() in a CPU hotplug
notifier with priority set so that these kthreads are unparked just after
the CPU has been added to the runqueues.

Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Paul E. McKenney   authored and   Ingo Molnar   commited 2015-04-13 08:25:16 +02:00
00df35f991
rcu: Handle outgoing CPUs on exit from idle loop 
This commit informs RCU of an outgoing CPU just before that CPU invokes
arch_cpu_idle_dead() during its last pass through the idle loop (via a
new CPU_DYING_IDLE notifier value).  This change means that RCU need not
deal with outgoing CPUs passing through the scheduler after informing
RCU that they are no longer online.  Note that removing the CPU from
the rcu_node ->qsmaskinit bit masks is done at CPU_DYING_IDLE time,
and orphaning callbacks is still done at CPU_DEAD time, the reason being
that at CPU_DEAD time we have another CPU that can adopt them.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Paul E. McKenney   commited 2015-03-12 15:19:38 -07:00
88428cc5c2
smpboot: Add common code for notification from dying CPU 
RCU ignores offlined CPUs, so they cannot safely run RCU read-side code.
(They -can- use SRCU, but not RCU.)  This means that any use of RCU
during or after the call to arch_cpu_idle_dead().  Unfortunately,
commit 2ed53c0d6c added a complete() call, which will contain RCU
read-side critical sections if there is a task waiting to be awakened.

Which, as it turns out, there almost never is.  In my qemu/KVM testing,
the to-be-awakened task is not yet asleep more than 99.5% of the time.
In current mainline, failure is even harder to reproduce, requiring a
virtualized environment that delays the outgoing CPU by at least three
jiffies between the time it exits its stop_machine() task at CPU_DYING
time and the time it calls arch_cpu_idle_dead() from the idle loop.
However, this problem really can occur, especially in virtualized
environments, and therefore really does need to be fixed

This suggests moving back to the polling loop, but using a much shorter
wait, with gentle exponential backoff instead of the old 100-millisecond
wait.  Most of the time, the loop will exit without waiting at all,
and almost all of the remaining uses will wait only five microseconds.
If the outgoing CPU is preempted, a loop will wait one jiffy, then
increase the wait by a factor of 11/10ths, rounding up.  As before, there
is a five-second timeout.

This commit therefore provides common-code infrastructure to do the
dying-to-surviving CPU handoff in a safe manner.  This code also
provides an indication at CPU-online of whether the CPU to be onlined
previously timed out on offline.  The new cpu_check_up_prepare() function
returns -EBUSY if this CPU previously took more than five seconds to
go offline, or -EAGAIN if it has not yet managed to go offline.  The
rationale for -EAGAIN is that it might still be preempted, so an additional
wait might well find it correctly offlined.  Architecture-specific code
can decide how to handle these conditions.  Systems in which CPUs take
themselves completely offline might respond to an -EBUSY return as if
it was a zero (success) return.  Systems in which the surviving CPU must
take some action might take it at this time, or might simply mark the
other CPU as unusable.

Note that architectures that take the easy way out and simply pass the
-EBUSY and -EAGAIN upwards will change the sysfs API.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <linux-api@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
[ paulmck: Fixed state machine for architectures that don't check earlier
  CPU-hotplug results as suggested by James Hogan. ]

Paul E. McKenney   commited 2015-03-11 13:20:25 -07:00
8038dad7e8
drivers: base: add cpu_device_create to support per-cpu devices 
This patch adds a new function to create per-cpu devices.
This helps in:
1. reusing the device infrastructure to create any cpu related
   attributes and corresponding sysfs instead of creating and
   dealing with raw kobjects directly
2. retaining the legacy path(/sys/devices/system/cpu/..) to support
   existing sysfs ABI
3. avoiding to create links in the bus directory pointing to the
   device as there would be per-cpu instance of these devices with
   the same name since dev->bus is not populated to cpu_sysbus on
   purpose

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Sudeep Holla   authored and   Greg Kroah-Hartman   commited 2014-11-07 11:45:00 -08:00
3d52943b3a
rcu: Eliminate deadlock between CPU hotplug and expedited grace periods 
Currently, the expedited grace-period primitives do get_online_cpus().
This greatly simplifies their implementation, but means that calls
to them holding locks that are acquired by CPU-hotplug notifiers (to
say nothing of calls to these primitives from CPU-hotplug notifiers)
can deadlock.  But this is starting to become inconvenient, as can be
seen here: https://lkml.org/lkml/2014/8/5/754.  The problem in this
case is that some developers need to acquire a mutex from a CPU-hotplug
notifier, but also need to hold it across a synchronize_rcu_expedited().
As noted above, this currently results in deadlock.

This commit avoids the deadlock and retains the simplicity by creating
a try_get_online_cpus(), which returns false if the get_online_cpus()
reference count could not immediately be incremented.  If a call to
try_get_online_cpus() returns true, the expedited primitives operate as
before.  If a call returns false, the expedited primitives fall back to
normal grace-period operations.  This falling back of course results in
increased grace-period latency, but only during times when CPU hotplug
operations are actually in flight.  The effect should therefore be
negligible during normal operation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Tested-by: Lan Tianyu <tianyu.lan@intel.com>

Paul E. McKenney   commited 2014-09-18 16:22:27 -07:00
dd56af42bd
idle: remove cpu_idle() forward declarations 
After all architectures were converted to the generic idle framework,
commit d190e8195b ("idle: Remove GENERIC_IDLE_LOOP config switch")
removed the last caller of cpu_idle().  The forward declarations in
header files were forgotten.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Geert Uytterhoeven   authored and   Linus Torvalds   commited 2014-06-06 16:08:18 -07:00
ae022622ae
CPU hotplug notifiers registration fixes for 3.15-rc1 
The purpose of this single series of commits from Srivatsa S Bhat (with
 a small piece from Gautham R Shenoy) touching multiple subsystems that use
 CPU hotplug notifiers is to provide a way to register them that will not
 lead to deadlocks with CPU online/offline operations as described in the
 changelog of commit 93ae4f978c (CPU hotplug: Provide lockless versions
 of callback registration functions).
 
 The first three commits in the series introduce the API and document it
 and the rest simply goes through the users of CPU hotplug notifiers and
 converts them to using the new method.
 
 /
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.22 (GNU/Linux)
 
 iQIcBAABCAAGBQJTQow2AAoJEILEb/54YlRxW4QQAJlYRDUzwFJzJzYhltQYuVR+
 4D74XMtvXgoJfg3cwdSWvMKKpJZnA9BVN0f7Hcx9wYmgdexYUuHeZJmMNyc3S2+g
 KjKBIsugvgmZhHbbLd6TJ6GBbhGT5JLt9VmSfL9zIkveInU1YHFUUqL/mxdHm4J0
 BSGKjk2rN3waRJgmY+xfliFLtQjDKFwJpMuvrgtoUyfas3f4sIV43UNbqdvA/weJ
 rzedxXOlKH/id4b56lj/4iIzcoL3mwvJJ7r6n0CEMsKv87z09kqR0O+69Tsq/cgs
 j17CsvoJOmZGk3QTeKVMQWBsvk6aPoDu3zK83gLbQMt+qjOpSTbJLz/3HZw4/TrW
 ss4nuZne1DLMGS+6hoxYbTP+6Ni//Kn+l/LrHc5jb7m1X3lMO4W2aV3IROtIE1rv
 lEP1IG01NU4u9YwkVj1dyhrkSp8tLPul4SrUK8W+oNweOC5crjJV7vJbIPJgmYiM
 IZN55wln0yVRtR4TX+rmvN0PixsInE8MeaVCmReApyF9pdzul/StxlBze5BKLSJD
 cqo1kNPpsmdxoDucqUpQ/gSvy+IOl2qnlisB5PpV93sk7De6TFDYrGHxjYIW7jMf
 StXwdCDDQhzd2Q8Kfpp895A1dbIl8rKtwA6bTU2eX+BfMVFzuMdT44cvosx1+UdQ
 sWl//rg76nb13dFjvF+q
 =SW7Q
 -----END PGP SIGNATURE-----

Merge tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull CPU hotplug notifiers registration fixes from Rafael Wysocki:
 "The purpose of this single series of commits from Srivatsa S Bhat
  (with a small piece from Gautham R Shenoy) touching multiple
  subsystems that use CPU hotplug notifiers is to provide a way to
  register them that will not lead to deadlocks with CPU online/offline
  operations as described in the changelog of commit 93ae4f978c ("CPU
  hotplug: Provide lockless versions of callback registration
  functions").

  The first three commits in the series introduce the API and document
  it and the rest simply goes through the users of CPU hotplug notifiers
  and converts them to using the new method"

* tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (52 commits)
  net/iucv/iucv.c: Fix CPU hotplug callback registration
  net/core/flow.c: Fix CPU hotplug callback registration
  mm, zswap: Fix CPU hotplug callback registration
  mm, vmstat: Fix CPU hotplug callback registration
  profile: Fix CPU hotplug callback registration
  trace, ring-buffer: Fix CPU hotplug callback registration
  xen, balloon: Fix CPU hotplug callback registration
  hwmon, via-cputemp: Fix CPU hotplug callback registration
  hwmon, coretemp: Fix CPU hotplug callback registration
  thermal, x86-pkg-temp: Fix CPU hotplug callback registration
  octeon, watchdog: Fix CPU hotplug callback registration
  oprofile, nmi-timer: Fix CPU hotplug callback registration
  intel-idle: Fix CPU hotplug callback registration
  clocksource, dummy-timer: Fix CPU hotplug callback registration
  drivers/base/topology.c: Fix CPU hotplug callback registration
  acpi-cpufreq: Fix CPU hotplug callback registration
  zsmalloc: Fix CPU hotplug callback registration
  scsi, fcoe: Fix CPU hotplug callback registration
  scsi, bnx2fc: Fix CPU hotplug callback registration
  scsi, bnx2i: Fix CPU hotplug callback registration
  ...

Linus Torvalds   commited 2014-04-07 14:55:46 -07:00
467a9e1633
CPU hotplug: Provide lockless versions of callback registration functions 
The following method of CPU hotplug callback registration is not safe
due to the possibility of an ABBA deadlock involving the cpu_add_remove_lock
and the cpu_hotplug.lock.

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

The deadlock is shown below:

          CPU 0                                         CPU 1
          -----                                         -----

   Acquire cpu_hotplug.lock
   [via get_online_cpus()]

                                              CPU online/offline operation
                                              takes cpu_add_remove_lock
                                              [via cpu_maps_update_begin()]

   Try to acquire
   cpu_add_remove_lock
   [via register_cpu_notifier()]

                                              CPU online/offline operation
                                              tries to acquire cpu_hotplug.lock
                                              [via cpu_hotplug_begin()]

                            *** DEADLOCK! ***

The problem here is that callback registration takes the locks in one order
whereas the CPU hotplug operations take the same locks in the opposite order.
To avoid this issue and to provide a race-free method to register CPU hotplug
callbacks (along with initialization of already online CPUs), introduce new
variants of the callback registration APIs that simply register the callbacks
without holding the cpu_add_remove_lock during the registration. That way,
we can avoid the ABBA scenario. However, we will need to hold the
cpu_add_remove_lock throughout the entire critical section, to protect updates
to the callback/notifier chain.

This can be achieved by writing the callback registration code as follows:

	cpu_maps_update_begin(); [ or cpu_notifier_register_begin(); see below ]

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	/* This doesn't take the cpu_add_remove_lock */
	__register_cpu_notifier(&foobar_cpu_notifier);

	cpu_maps_update_done();  [ or cpu_notifier_register_done(); see below ]

Note that we can't use get_online_cpus() here instead of cpu_maps_update_begin()
because the cpu_hotplug.lock is dropped during the invocation of CPU_POST_DEAD
notifiers, and hence get_online_cpus() cannot provide the necessary
synchronization to protect the callback/notifier chains against concurrent
reads and writes. On the other hand, since the cpu_add_remove_lock protects
the entire hotplug operation (including CPU_POST_DEAD), we can use
cpu_maps_update_begin/done() to guarantee proper synchronization.

Also, since cpu_maps_update_begin/done() is like a super-set of
get/put_online_cpus(), the former naturally protects the critical sections
from concurrent hotplug operations.

Since the names cpu_maps_update_begin/done() don't make much sense in CPU
hotplug callback registration scenarios, we'll introduce new APIs named
cpu_notifier_register_begin/done() and map them to cpu_maps_update_begin/done().

In summary, introduce the lockless variants of un/register_cpu_notifier() and
also export the cpu_notifier_register_begin/done() APIs for use by modules.
This way, we provide a race-free way to register hotplug callbacks as well as
perform initialization for the CPUs that are already online.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Srivatsa S. Bhat   authored and   Rafael J. Wysocki   commited 2014-03-20 13:43:40 +01:00
93ae4f978c
x86: align x86 arch with generic CPU modalias handling 
The x86 CPU feature modalias handling existed before it was reimplemented
generically. This patch aligns the x86 handling so that it
(a) reuses some more code that is now generic;
(b) uses the generic format for the modalias module metadata entry, i.e., it
    now uses 'cpu:type:x86,venVVVVfamFFFFmodMMMM:feature:,XXXX,YYYY' instead of
    the 'x86cpu:vendor:VVVV👪FFFF:model:MMMM:feature:,XXXX,YYYY' that was
    used before.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Ard Biesheuvel   authored and   Greg Kroah-Hartman   commited 2014-02-18 12:45:38 -08:00
2b9c1f0327
ACPI and power management updates for 3.13-rc1 
- New power capping framework and the the Intel Running Average Power
    Limit (RAPL) driver using it from Srinivas Pandruvada and Jacob Pan.
 
  - Addition of the in-kernel switching feature to the arm_big_little
    cpufreq driver from Viresh Kumar and Nicolas Pitre.
 
  - cpufreq support for iMac G5 from Aaro Koskinen.
 
  - Baytrail processors support for intel_pstate from Dirk Brandewie.
 
  - cpufreq support for Midway/ECX-2000 from Mark Langsdorf.
 
  - ARM vexpress/TC2 cpufreq support from Sudeep KarkadaNagesha.
 
  - ACPI power management support for the I2C and SPI bus types from
    Mika Westerberg and Lv Zheng.
 
  - cpufreq core fixes and cleanups from Viresh Kumar, Srivatsa S Bhat,
    Stratos Karafotis, Xiaoguang Chen, Lan Tianyu.
 
  - cpufreq drivers updates (mostly fixes and cleanups) from Viresh Kumar,
    Aaro Koskinen, Jungseok Lee, Sudeep KarkadaNagesha, Lukasz Majewski,
    Manish Badarkhe, Hans-Christian Egtvedt, Evgeny Kapaev.
 
  - intel_pstate updates from Dirk Brandewie and Adrian Huang.
 
  - ACPICA update to version 20130927 includig fixes and cleanups and
    some reduction of divergences between the ACPICA code in the kernel
    and ACPICA upstream in order to improve the automatic ACPICA patch
    generation process.  From Bob Moore, Lv Zheng, Tomasz Nowicki,
    Naresh Bhat, Bjorn Helgaas, David E Box.
 
  - ACPI IPMI driver fixes and cleanups from Lv Zheng.
 
  - ACPI hotplug fixes and cleanups from Bjorn Helgaas, Toshi Kani,
    Zhang Yanfei, Rafael J Wysocki.
 
  - Conversion of the ACPI AC driver to the platform bus type and
    multiple driver fixes and cleanups related to ACPI from Zhang Rui.
 
  - ACPI processor driver fixes and cleanups from Hanjun Guo, Jiang Liu,
    Bartlomiej Zolnierkiewicz, Mathieu Rhéaume, Rafael J Wysocki.
 
  - Fixes and cleanups and new blacklist entries related to the ACPI
    video support from Aaron Lu, Felipe Contreras, Lennart Poettering,
    Kirill Tkhai.
 
  - cpuidle core cleanups from Viresh Kumar and Lorenzo Pieralisi.
 
  - cpuidle drivers fixes and cleanups from Daniel Lezcano, Jingoo Han,
    Bartlomiej Zolnierkiewicz, Prarit Bhargava.
 
  - devfreq updates from Sachin Kamat, Dan Carpenter, Manish Badarkhe.
 
  - Operation Performance Points (OPP) core updates from Nishanth Menon.
 
  - Runtime power management core fix from Rafael J Wysocki and update
    from Ulf Hansson.
 
  - Hibernation fixes from Aaron Lu and Rafael J Wysocki.
 
  - Device suspend/resume lockup detection mechanism from Benoit Goby.
 
  - Removal of unused proc directories created for various ACPI drivers
    from Lan Tianyu.
 
  - ACPI LPSS driver fix and new device IDs for the ACPI platform scan
    handler from Heikki Krogerus and Jarkko Nikula.
 
  - New ACPI _OSI blacklist entry for Toshiba NB100 from Levente Kurusa.
 
  - Assorted fixes and cleanups related to ACPI from Andy Shevchenko,
    Al Stone, Bartlomiej Zolnierkiewicz, Colin Ian King, Dan Carpenter,
    Felipe Contreras, Jianguo Wu, Lan Tianyu, Yinghai Lu, Mathias Krause,
    Liu Chuansheng.
 
  - Assorted PM fixes and cleanups from Andy Shevchenko, Thierry Reding,
    Jean-Christophe Plagniol-Villard.
 
 /
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.19 (GNU/Linux)
 
 iQIcBAABCAAGBQJSfPKLAAoJEILEb/54YlRxH6YQAJwDKi25RCZziFSIenXuqzC/
 c6JxoH/tSnDHJHhcTgqh7H7Raa+zmatMDf0m2oEv2Wjfx4Lt4BQK4iefhe/zY4lX
 yJ8uXDg+U8DYhDX2XwbwnFpd1M1k/A+s2gIHDTHHGnE0kDngXdd8RAFFktBmooTZ
 l5LBQvOrTlgX/ZfqI/MNmQ6lfY6kbCABGSHV1tUUsDA6Kkvk/LAUTOMSmptv1q22
 hcs6k55vR34qADPkUX5GghjmcYJv+gNtvbDEJUjcmCwVoPWouF415m7R5lJ8w3/M
 49Q8Tbu5HELWLwca64OorS8qh/P7sgUOf1BX5IDzHnJT+TGeDfvcYbMv2Z275/WZ
 /bqhuLuKBpsHQ2wvEeT+lYV3FlifKeTf1FBxER3ApjzI3GfpmVVQ+dpEu8e9hcTh
 ZTPGzziGtoIsHQ0unxb+zQOyt1PmIk+cU4IsKazs5U20zsVDMcKzPrb19Od49vMX
 gCHvRzNyOTqKWpE83Ss4NGOVPAG02AXiXi/BpuYBHKDy6fTH/liKiCw5xlCDEtmt
 lQrEbupKpc/dhCLo5ws6w7MZzjWJs2eSEQcNR4DlR++pxIpYOOeoPTXXrghgZt2X
 mmxZI2qsJ7GAvPzII8OBeF3CRO3fabZ6Nez+M+oEZjGe05ZtpB3ccw410HwieqBn
 dYpJFt/BHK189odhV9CM
 =JCxk
 -----END PGP SIGNATURE-----

Merge tag 'pm+acpi-3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI and power management updates from Rafael J Wysocki:

 - New power capping framework and the the Intel Running Average Power
   Limit (RAPL) driver using it from Srinivas Pandruvada and Jacob Pan.

 - Addition of the in-kernel switching feature to the arm_big_little
   cpufreq driver from Viresh Kumar and Nicolas Pitre.

 - cpufreq support for iMac G5 from Aaro Koskinen.

 - Baytrail processors support for intel_pstate from Dirk Brandewie.

 - cpufreq support for Midway/ECX-2000 from Mark Langsdorf.

 - ARM vexpress/TC2 cpufreq support from Sudeep KarkadaNagesha.

 - ACPI power management support for the I2C and SPI bus types from Mika
   Westerberg and Lv Zheng.

 - cpufreq core fixes and cleanups from Viresh Kumar, Srivatsa S Bhat,
   Stratos Karafotis, Xiaoguang Chen, Lan Tianyu.

 - cpufreq drivers updates (mostly fixes and cleanups) from Viresh
   Kumar, Aaro Koskinen, Jungseok Lee, Sudeep KarkadaNagesha, Lukasz
   Majewski, Manish Badarkhe, Hans-Christian Egtvedt, Evgeny Kapaev.

 - intel_pstate updates from Dirk Brandewie and Adrian Huang.

 - ACPICA update to version 20130927 includig fixes and cleanups and
   some reduction of divergences between the ACPICA code in the kernel
   and ACPICA upstream in order to improve the automatic ACPICA patch
   generation process.  From Bob Moore, Lv Zheng, Tomasz Nowicki, Naresh
   Bhat, Bjorn Helgaas, David E Box.

 - ACPI IPMI driver fixes and cleanups from Lv Zheng.

 - ACPI hotplug fixes and cleanups from Bjorn Helgaas, Toshi Kani, Zhang
   Yanfei, Rafael J Wysocki.

 - Conversion of the ACPI AC driver to the platform bus type and
   multiple driver fixes and cleanups related to ACPI from Zhang Rui.

 - ACPI processor driver fixes and cleanups from Hanjun Guo, Jiang Liu,
   Bartlomiej Zolnierkiewicz, Mathieu Rhéaume, Rafael J Wysocki.

 - Fixes and cleanups and new blacklist entries related to the ACPI
   video support from Aaron Lu, Felipe Contreras, Lennart Poettering,
   Kirill Tkhai.

 - cpuidle core cleanups from Viresh Kumar and Lorenzo Pieralisi.

 - cpuidle drivers fixes and cleanups from Daniel Lezcano, Jingoo Han,
   Bartlomiej Zolnierkiewicz, Prarit Bhargava.

 - devfreq updates from Sachin Kamat, Dan Carpenter, Manish Badarkhe.

 - Operation Performance Points (OPP) core updates from Nishanth Menon.

 - Runtime power management core fix from Rafael J Wysocki and update
   from Ulf Hansson.

 - Hibernation fixes from Aaron Lu and Rafael J Wysocki.

 - Device suspend/resume lockup detection mechanism from Benoit Goby.

 - Removal of unused proc directories created for various ACPI drivers
   from Lan Tianyu.

 - ACPI LPSS driver fix and new device IDs for the ACPI platform scan
   handler from Heikki Krogerus and Jarkko Nikula.

 - New ACPI _OSI blacklist entry for Toshiba NB100 from Levente Kurusa.

 - Assorted fixes and cleanups related to ACPI from Andy Shevchenko, Al
   Stone, Bartlomiej Zolnierkiewicz, Colin Ian King, Dan Carpenter,
   Felipe Contreras, Jianguo Wu, Lan Tianyu, Yinghai Lu, Mathias Krause,
   Liu Chuansheng.

 - Assorted PM fixes and cleanups from Andy Shevchenko, Thierry Reding,
   Jean-Christophe Plagniol-Villard.

* tag 'pm+acpi-3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (386 commits)
  cpufreq: conservative: fix requested_freq reduction issue
  ACPI / hotplug: Consolidate deferred execution of ACPI hotplug routines
  PM / runtime: Use pm_runtime_put_sync() in __device_release_driver()
  ACPI / event: remove unneeded NULL pointer check
  Revert "ACPI / video: Ignore BIOS initial backlight value for HP 250 G1"
  ACPI / video: Quirk initial backlight level 0
  ACPI / video: Fix initial level validity test
  intel_pstate: skip the driver if ACPI has power mgmt option
  PM / hibernate: Avoid overflow in hibernate_preallocate_memory()
  ACPI / hotplug: Do not execute "insert in progress" _OST
  ACPI / hotplug: Carry out PCI root eject directly
  ACPI / hotplug: Merge device hot-removal routines
  ACPI / hotplug: Make acpi_bus_hot_remove_device() internal
  ACPI / hotplug: Simplify device ejection routines
  ACPI / hotplug: Fix handle_root_bridge_removal()
  ACPI / hotplug: Refuse to hot-remove all objects with disabled hotplug
  ACPI / scan: Start matching drivers after trying scan handlers
  ACPI: Remove acpi_pci_slot_init() headers from internal.h
  ACPI / blacklist: fix name of ThinkPad Edge E530
  PowerCap: Fix build error with option -Werror=format-security
  ...

Conflicts:
	arch/arm/mach-omap2/opp.c
	drivers/Kconfig
	drivers/spi/spi.c

Linus Torvalds   commited 2013-11-14 13:41:48 +09:00
f9300eaaac
of: Make cpu node handling more portable. 
Use for_each_node_by_type() to iterate all cpu nodes in the
system.

Provide and overridable function arch_find_n_match_cpu_physical_id,
which sees if the given device node matches 'cpu' and if so sets
'*thread' when non-NULL to the cpu thread number within the core.

The default implementation behaves the same as the existing code.

Add a sparc64 implementation.

Signed-off-by: David S. Miller <davem@davemloft.net>
Tested-by: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@arm.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

David Miller   authored and   Grant Likely   commited 2013-10-15 20:09:10 +01:00
d1cb9d1af0
hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock() 
cpu_hotplug_driver_lock() serializes CPU online/offline operations
when ARCH_CPU_PROBE_RELEASE is set.  This lock interface is no longer
necessary with the following reason:

 - lock_device_hotplug() now protects CPU online/offline operations,
   including the probe & release interfaces enabled by
   ARCH_CPU_PROBE_RELEASE.  The use of cpu_hotplug_driver_lock() is
   redundant.
 - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE
   is defined, which is misleading and is only enabled on powerpc.

This patch removes the cpu_hotplug_driver_lock() interface.  As
a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu
probe & release interface as intended.  There is no functional change
in this patch.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Toshi Kani   authored and   Rafael J. Wysocki   commited 2013-09-30 19:55:51 +02:00
6dedcca610
Merge branch 'pm-cpufreq' 
* 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
  ...

Rafael J. Wysocki   commited 2013-08-27 01:44:40 +02:00
7a330a5416
of: move of_get_cpu_node implementation to DT core library 
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 <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

Sudeep KarkadaNagesha   commited 2013-08-21 10:24:44 +01:00
183912d352
ACPI / processor: Acquire writer lock to update CPU maps 
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 <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Toshi Kani   authored and   Rafael J. Wysocki   commited 2013-08-13 12:20:16 +02:00
b9d10be7a8
kernel: delete __cpuinit usage from all core kernel files 
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 <paul.gortmaker@windriver.com>

Paul Gortmaker   commited 2013-07-14 19:36:59 -04:00
0db0628d90
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 
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
  ...

Linus Torvalds   commited 2013-07-04 11:40:58 -07:00
80cc38b163
CPU hotplug: provide a generic helper to disable/enable CPU hotplug 
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 <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Robin Holt <holt@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Srivatsa S. Bhat   authored and   Linus Torvalds   commited 2013-06-12 16:29:44 -07:00
16e53dbf10
include/linux/cpu.h: Update comments to reflect reality 
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 <rpjday@crashcourse.ca>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Robert P. J. Day   authored and   Jiri Kosina   commited 2013-05-28 12:02:11 +02:00
611a75e187
idle: Implement generic idle function 
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 <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130321215233.646635455@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2013-04-08 17:39:23 +02:00
d166991234
idle: Provide a generic entry point for the idle code 
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 <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130321215233.583190032@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Thomas Gleixner   commited 2013-04-08 17:39:23 +02:00
a1a04ec3c7
workqueue: perform cpu down operations from low priority cpu_notifier() 
Currently, all workqueue cpu hotplug operations run off
CPU_PRI_WORKQUEUE which is higher than normal notifiers.  This is to
ensure that workqueue is up and running while bringing up a CPU before
other notifiers try to use workqueue on the CPU.

Per-cpu workqueues are supposed to remain working and bound to the CPU
for normal CPU_DOWN_PREPARE notifiers.  This holds mostly true even
with workqueue offlining running with higher priority because
workqueue CPU_DOWN_PREPARE only creates a bound trustee thread which
runs the per-cpu workqueue without concurrency management without
explicitly detaching the existing workers.

However, if the trustee needs to create new workers, it creates
unbound workers which may wander off to other CPUs while
CPU_DOWN_PREPARE notifiers are in progress.  Furthermore, if the CPU
down is cancelled, the per-CPU workqueue may end up with workers which
aren't bound to the CPU.

While reliably reproducible with a convoluted artificial test-case
involving scheduling and flushing CPU burning work items from CPU down
notifiers, this isn't very likely to happen in the wild, and, even
when it happens, the effects are likely to be hidden by the following
successful CPU down.

Fix it by using different priorities for up and down notifiers - high
priority for up operations and low priority for down operations.

Workqueue cpu hotplug operations will soon go through further cleanup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>

Tejun Heo   commited 2012-07-17 12:39:26 -07:00
6575820221
cpu: introduce clear_tasks_mm_cpumask() helper 
Many architectures clear tasks' mm_cpumask like this:

	read_lock(&tasklist_lock);
	for_each_process(p) {
		if (p->mm)
			cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
	}
	read_unlock(&tasklist_lock);

Depending on the context, the code above may have several problems,
such as:

1. Working with task->mm w/o getting mm or grabing the task lock is
   dangerous as ->mm might disappear (exit_mm() assigns NULL under
   task_lock(), so tasklist lock is not enough).

2. Checking for process->mm is not enough because process' main
   thread may exit or detach its mm via use_mm(), but other threads
   may still have a valid mm.

This patch implements a small helper function that does things
correctly, i.e.:

1. We take the task's lock while whe handle its mm (we can't use
   get_task_mm()/mmput() pair as mmput() might sleep);

2. To catch exited main thread case, we use find_lock_task_mm(),
   which walks up all threads and returns an appropriate task
   (with task lock held).

Also, Per Peter Zijlstra's idea, now we don't grab tasklist_lock in
the new helper, instead we take the rcu read lock. We can do this
because the function is called after the cpu is taken down and marked
offline, so no new tasks will get this cpu set in their mm mask.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Anton Vorontsov   authored and   Linus Torvalds   commited 2012-05-31 17:49:29 -07:00
cb79295e20
sched: Remove stale power aware scheduling remnants and dysfunctional knobs 
It's been broken forever (i.e. it's not scheduling in a power
aware fashion), as reported by Suresh and others sending
patches, and nobody cares enough to fix it properly ...
so remove it to make space free for something better.

There's various problems with the code as it stands today, first
and foremost the user interface which is bound to topology
levels and has multiple values per level. This results in a
state explosion which the administrator or distro needs to
master and almost nobody does.

Furthermore large configuration state spaces aren't good, it
means the thing doesn't just work right because it's either
under so many impossibe to meet constraints, or even if
there's an achievable state workloads have to be aware of
it precisely and can never meet it for dynamic workloads.

So pushing this kind of decision to user-space was a bad idea
even with a single knob - it's exponentially worse with knobs
on every node of the topology.

There is a proposal to replace the user interface with a single
3 state knob:

 sched_balance_policy := { performance, power, auto }

where 'auto' would be the preferred default which looks at things
like Battery/AC mode and possible cpufreq state or whatever the hw
exposes to show us power use expectations - but there's been no
progress on it in the past many months.

Aside from that, the actual implementation of the various knobs
is known to be broken. There have been sporadic attempts at
fixing things but these always stop short of reaching a mergable
state.

Therefore this wholesale removal with the hopes of spurring
people who care to come forward once again and work on a
coherent replacement.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1326104915.2442.53.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Peter Zijlstra   authored and   Ingo Molnar   commited 2012-05-17 13:48:56 +02:00
8e7fbcbc22
The following text was taken from the original review request: 
"[RFC PATCH 0/2] audit of linux/device.h users in include/*"
 		https://lkml.org/lkml/2012/3/4/159
 --
 
 Nearly every subsystem has some kind of header with a proto like:
 
 	void foo(struct device *dev);
 
 and yet there is no reason for most of these guys to care about the
 sub fields within the device struct.  This allows us to significantly
 reduce the scope of headers including headers.  For this instance, a
 reduction of about 40% is achieved by replacing the include with the
 simple fact that the device is some kind of a struct.
 
 Unlike the much larger module.h cleanup, this one is simply two
 commits.  One to fix the implicit <linux/device.h> users, and then
 one to delete the device.h includes from the linux/include/ dir
 wherever possible.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1.4.11 (GNU/Linux)
 
 iQIcBAABAgAGBQJPbNxLAAoJEOvOhAQsB9HWR6QQAMRUZ94O2069/nW9h4TO/xTr
 Hq/80lo/TBBiRmob3iWBP76lzgeeMPPVEX1I6N7YYlhL3IL7HsaJH1DvpIPPHXQP
 GFKcBsZ5ZLV8c4CBDSr+/HFNdhXc0bw0awBjBvR7gAsWuZpNFn4WbhizJi4vWAoE
 4ydhPu55G1G8TkBtYLJQ8xavxsmiNBSDhd2i+0vn6EVpgmXynjOMG8qXyaS97Jvg
 pZLwnN5Wu21coj6+xH3QUKCl1mJ+KGyamWX5gFBVIfsDB3k5H4neijVm7t1en4b0
 cWxmXeR/JE3VLEl/17yN2dodD8qw1QzmTWzz1vmwJl2zK+rRRAByBrL0DP7QCwCZ
 ppeJbdhkMBwqjtknwrmMwsuAzUdJd79GXA+6Vm+xSEkr6FEPK1M0kGbvaqV9Usgd
 ohMewewbO6ddgR9eF7Kw2FAwo0hwkPNEplXIym9rZzFG1h+T0STGSHvkn7LV765E
 ul1FapSV3GCxEVRwWTwD28FLU2+0zlkOZ5sxXwNPTT96cNmW+R7TGuslZKNaMNjX
 q7eBZxo8DtVt/jqJTntR8bs8052c8g1Ac1IKmlW8VSmFwT1M6VBGRn1/JWAhuUgv
 dBK/FF+I1GJTAJWIhaFcKXLHvmV9uhS6JaIhLMDOetoOkpqSptJ42hDG+89WkFRk
 o55GQ5TFdoOpqxVzGbvE
 =3j4+
 -----END PGP SIGNATURE-----

Merge tag 'device-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

Pull <linux/device.h> avoidance patches from Paul Gortmaker:
 "Nearly every subsystem has some kind of header with a proto like:

	void foo(struct device *dev);

  and yet there is no reason for most of these guys to care about the
  sub fields within the device struct.  This allows us to significantly
  reduce the scope of headers including headers.  For this instance, a
  reduction of about 40% is achieved by replacing the include with the
  simple fact that the device is some kind of a struct.

  Unlike the much larger module.h cleanup, this one is simply two
  commits.  One to fix the implicit <linux/device.h> users, and then one
  to delete the device.h includes from the linux/include/ dir wherever
  possible."

* tag 'device-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
  device.h: audit and cleanup users in main include dir
  device.h: cleanup users outside of linux/include (C files)

Linus Torvalds   commited 2012-03-24 10:41:37 -07:00
250f6715a4
device.h: audit and cleanup users in main include dir 
The <linux/device.h> header includes a lot of stuff, and
it in turn gets a lot of use just for the basic "struct device"
which appears so often.

Clean up the users as follows:

1) For those headers only needing "struct device" as a pointer
in fcn args, replace the include with exactly that.

2) For headers not really using anything from device.h, simply
delete the include altogether.

3) For headers relying on getting device.h implicitly before
being included themselves, now explicitly include device.h

4) For files in which doing #1 or #2 uncovers an implicit
dependency on some other header, fix by explicitly adding
the required header(s).

Any C files that were implicitly relying on device.h to be
present have already been dealt with in advance.

Total removals from #1 and #2: 51.  Total additions coming
from #3: 9.  Total other implicit dependencies from #4: 7.

As of 3.3-rc1, there were 110, so a net removal of 42 gives
about a 38% reduction in device.h presence in include/*

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

Paul Gortmaker   commited 2012-03-16 10:38:24 -04:00
313162d0b8
CPU: Introduce ARCH_HAS_CPU_AUTOPROBE and X86 parts 
This patch is based on Andi Kleen's work:
Implement autoprobing/loading of modules serving CPU
specific features (x86cpu autoloading).

And Kay Siever's work to get rid of sysdev cpu structures
and making use of struct device instead.

Before, the cpuid driver had to be loaded to get the x86cpu
autoloading feature. With this patch autoloading works through
the /sys/devices/system/cpu object

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Thomas Renninger   authored and   Greg Kroah-Hartman   commited 2012-01-26 16:49:08 -08:00
fad12ac8c8
Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core 
* 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (73 commits)
  arm: fix up some samsung merge sysdev conversion problems
  firmware: Fix an oops on reading fw_priv->fw in sysfs loading file
  Drivers:hv: Fix a bug in vmbus_driver_unregister()
  driver core: remove __must_check from device_create_file
  debugfs: add missing #ifdef HAS_IOMEM
  arm: time.h: remove device.h #include
  driver-core: remove sysdev.h usage.
  clockevents: remove sysdev.h
  arm: convert sysdev_class to a regular subsystem
  arm: leds: convert sysdev_class to a regular subsystem
  kobject: remove kset_find_obj_hinted()
  m86k: gpio - convert sysdev_class to a regular subsystem
  mips: txx9_sram - convert sysdev_class to a regular subsystem
  mips: 7segled - convert sysdev_class to a regular subsystem
  sh: dma - convert sysdev_class to a regular subsystem
  sh: intc - convert sysdev_class to a regular subsystem
  power: suspend - convert sysdev_class to a regular subsystem
  power: qe_ic - convert sysdev_class to a regular subsystem
  power: cmm - convert sysdev_class to a regular subsystem
  s390: time - convert sysdev_class to a regular subsystem
  ...

Fix up conflicts with 'struct sysdev' removal from various platform
drivers that got changed:
 - arch/arm/mach-exynos/cpu.c
 - arch/arm/mach-exynos/irq-eint.c
 - arch/arm/mach-s3c64xx/common.c
 - arch/arm/mach-s3c64xx/cpu.c
 - arch/arm/mach-s5p64x0/cpu.c
 - arch/arm/mach-s5pv210/common.c
 - arch/arm/plat-samsung/include/plat/cpu.h
 - arch/powerpc/kernel/sysfs.c
and fix up cpu_is_hotpluggable() as per Greg in include/linux/cpu.h

Linus Torvalds   commited 2012-01-07 12:03:30 -08:00
7affca3537
cpu: convert 'cpu' and 'machinecheck' sysdev_class to a regular subsystem 
This moves the 'cpu sysdev_class' over to a regular 'cpu' subsystem
and converts the devices to regular devices. The sysdev drivers are
implemented as subsystem interfaces now.

After all sysdev classes are ported to regular driver core entities, the
sysdev implementation will be entirely removed from the kernel.

Userspace relies on events and generic sysfs subsystem infrastructure
from sysdev devices, which are made available with this conversion.

Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <bp@amd64.org>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Cc: Len Brown <lenb@kernel.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Kay Sievers   authored and   Greg Kroah-Hartman   commited 2011-12-21 14:29:42 -08:00
8a25a2fd12
driver-core/cpu: Expose hotpluggability to the rest of the kernel 
When architectures register CPUs, they indicate whether the CPU allows
hotplugging; notably, x86 and ARM don't allow hotplugging CPU 0.
Userspace can easily query the hotpluggability of a CPU via sysfs;
however, the kernel has no convenient way of accessing that property in
an architecture-independent way.  While the kernel can simply try it and
see, some code needs to distinguish between "hotplug failed" and
"hotplug has no hope of working on this CPU"; for example, rcutorture's
CPU hotplug tests want to avoid drowning out real hotplug failures with
expected failures.

Expose this property via a new cpu_is_hotpluggable function, so that the
rest of the kernel can access it in an architecture-independent way.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Josh Triplett   authored and   Paul E. McKenney   commited 2011-12-11 10:32:20 -08:00
2987557f52
PM / Sleep: Remove unused symbol 'suspend_cpu_hotplug' 
Remove the suspend_cpu_hotplug declaration, which doesn't correspond
to an existing variable.

[rjw: Added the changelog.]

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

Srivatsa S. Bhat   authored and   Rafael J. Wysocki   commited 2011-11-04 22:28:09 +01:00
4e71c9545b
notifiers: cpu: move cpu notifiers into cpu.h 
We presently define all kinds of notifiers in notifier.h.  This is not
necessary at all, since different subsystems use different notifiers, they
are almost non-related with each other.

This can also save much build time.  Suppose I add a new netdevice event,
really I don't have to recompile all the source, just network related.
Without this patch, all the source will be recompiled.

I move the notify events near to their subsystem notifier registers, so
that they can be found more easily.

This patch:

It is not necessary to share the same notifier.h.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: David Miller <davem@davemloft.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Amerigo Wang   authored and   Linus Torvalds   commited 2011-07-25 20:57:14 -07:00
80f1ff97d0
driver core: prune docs about device_interface 
drivers/base/intf.c was removed before the beginning of (git) time but
its Documentation stuck around.  Remove it.

Signed-off-by: Brandon Philips <brandon@ifup.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Brandon Philips   authored and   Greg Kroah-Hartman   commited 2010-11-10 16:57:11 -08:00
b17cd8d69a
workqueue: reimplement CPU hotplugging support using trustee 
Reimplement CPU hotplugging support using trustee thread.  On CPU
down, a trustee thread is created and each step of CPU down is
executed by the trustee and workqueue_cpu_callback() simply drives and
waits for trustee state transitions.

CPU down operation no longer waits for works to be drained but trustee
sticks around till all pending works have been completed.  If CPU is
brought back up while works are still draining,
workqueue_cpu_callback() tells trustee to step down and tell workers
to rebind to the cpu.

As it's difficult to tell whether cwqs are empty if it's freezing or
frozen, trustee doesn't consider draining to be complete while a gcwq
is freezing or frozen (tracked by new GCWQ_FREEZING flag).  Also,
workers which get unbound from their cpu are marked with WORKER_ROGUE.

Trustee based implementation doesn't bring any new feature at this
point but it will be used to manage worker pool when dynamic shared
worker pool is implemented.

Signed-off-by: Tejun Heo <tj@kernel.org>

Tejun Heo   commited 2010-06-29 10:07:12 +02:00
db7bccf45c
sched: adjust when cpu_active and cpuset configurations are updated during cpu on/offlining 
Currently, when a cpu goes down, cpu_active is cleared before
CPU_DOWN_PREPARE starts and cpuset configuration is updated from a
default priority cpu notifier.  When a cpu is coming up, it's set
before CPU_ONLINE but cpuset configuration again is updated from the
same cpu notifier.

For cpu notifiers, this presents an inconsistent state.  Threads which
a CPU_DOWN_PREPARE notifier expects to be bound to the CPU can be
migrated to other cpus because the cpu is no more inactive.

Fix it by updating cpu_active in the highest priority cpu notifier and
cpuset configuration in the second highest when a cpu is coming up.
Down path is updated similarly.  This guarantees that all other cpu
notifiers see consistent cpu_active and cpuset configuration.

cpuset_track_online_cpus() notifier is converted to
cpuset_update_active_cpus() which just updates the configuration and
now called from cpuset_cpu_[in]active() notifiers registered from
sched_init_smp().  If cpuset is disabled, cpuset_update_active_cpus()
degenerates into partition_sched_domains() making separate notifier
for !CONFIG_CPUSETS unnecessary.

This problem is triggered by cmwq.  During CPU_DOWN_PREPARE, hotplug
callback creates a kthread and kthread_bind()s it to the target cpu,
and the thread is expected to run on that cpu.

* Ingo's test discovered __cpuinit/exit markups were incorrect.
  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Menage <menage@google.com>

Tejun Heo   commited 2010-06-08 21:40:36 +02:00
3a101d0548
sched: define and use CPU_PRI_* enums for cpu notifier priorities 
Instead of hardcoding priority 10 and 20 in sched and perf, collect
them into CPU_PRI_* enums.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>

Tejun Heo   commited 2010-06-08 21:40:36 +02:00
50a323b730
powerpc/pseries: Serialize cpu hotplug operations during deactivate Vs deallocate 
Currently the cpu-allocation/deallocation process comprises of two steps:
- Set the indicators and to update the device tree with DLPAR node
  information.

- Online/offline the allocated/deallocated CPU.

This is achieved by writing to the sysfs tunables "probe" during allocation
and "release" during deallocation.

At the sametime, the userspace can independently online/offline the CPUs of
the system using the sysfs tunable "online".

It is quite possible that when a userspace tool offlines a CPU
for the purpose of deallocation and is in the process of updating the device
tree, some other userspace tool could bring the CPU back online by writing to
the "online" sysfs tunable thereby causing the deallocate process to fail.

The solution to this is to serialize writes to the "probe/release" sysfs
tunable with the writes to the "online" sysfs tunable.

This patch employs a mutex to provide this serialization, which is a no-op on
all architectures except PPC_PSERIES

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Acked-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Gautham R Shenoy   authored and   Benjamin Herrenschmidt   commited 2009-12-09 17:09:36 +11:00
51badebdcf