When doing an nmi backtrace of many cores, most of which are idle, the
output is a little overwhelming and very uninformative. Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".
We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the interrupted
PC to see if it lies within that section.
This commit suitably tags x86 and tile idle routines, and only adds in
the minimal framework for other architectures.
Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org> [arm]
Tested-by: Petr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull CPU hotplug updates from Thomas Gleixner:
"Yet another batch of cpu hotplug core updates and conversions:
- Provide core infrastructure for multi instance drivers so the
drivers do not have to keep custom lists.
- Convert custom lists to the new infrastructure. The block-mq custom
list conversion comes through the block tree and makes the diffstat
tip over to more lines removed than added.
- Handle unbalanced hotplug enable/disable calls more gracefully.
- Remove the obsolete CPU_STARTING/DYING notifier support.
- Convert another batch of notifier users.
The relayfs changes which conflicted with the conversion have been
shipped to me by Andrew.
The remaining lot is targeted for 4.10 so that we finally can remove
the rest of the notifiers"
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
cpufreq: Fix up conversion to hotplug state machine
blk/mq: Reserve hotplug states for block multiqueue
x86/apic/uv: Convert to hotplug state machine
s390/mm/pfault: Convert to hotplug state machine
mips/loongson/smp: Convert to hotplug state machine
mips/octeon/smp: Convert to hotplug state machine
fault-injection/cpu: Convert to hotplug state machine
padata: Convert to hotplug state machine
cpufreq: Convert to hotplug state machine
ACPI/processor: Convert to hotplug state machine
virtio scsi: Convert to hotplug state machine
oprofile/timer: Convert to hotplug state machine
block/softirq: Convert to hotplug state machine
lib/irq_poll: Convert to hotplug state machine
x86/microcode: Convert to hotplug state machine
sh/SH-X3 SMP: Convert to hotplug state machine
ia64/mca: Convert to hotplug state machine
ARM/OMAP/wakeupgen: Convert to hotplug state machine
ARM/shmobile: Convert to hotplug state machine
arm64/FP/SIMD: Convert to hotplug state machine
...
All users are converted to state machine, remove CPU_STARTING and the
corresponding CPU_DYING.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-2-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
disable_nonboot_cpus() assumes that the lowest numbered online CPU is
the boot CPU, and that this is the correct CPU to run any power
management code on.
On x86 this is always correct, as CPU0 cannot (easily) by taken offline.
On arm64 CPU0 can be taken offline. For hibernate/resume this means we
may hibernate on a CPU other than CPU0. If the system is rebooted with
kexec 'CPU0' will be assigned to a different physical CPU. This
complicates hibernate/resume as now we can't trust the CPU numbers.
Arch code can find the correct physical CPU, and ensure it is online
before resume from hibernate begins, but also needs to influence
disable_nonboot_cpus()s choice of CPU.
Rename disable_nonboot_cpus() as freeze_secondary_cpus() and add an
argument indicating which CPU should be left standing. Follow the logic
in migrate_to_reboot_cpu() to use the lowest numbered online CPU if the
requested CPU is not online.
Add disable_nonboot_cpus() as an inline function that has the existing
behaviour.
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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. ]
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>
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>
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>
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.
/
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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
...
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>
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>
- 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.
/
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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
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>
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>
* 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
...
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>
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>
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>
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
...
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>
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>
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>
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>
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>
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>
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>
"[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.
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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)
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>
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>
* '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
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>
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>
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>
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>
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>
Chris Metcalf