Install the callbacks via the state machine.

This is just a temporary vehicle to keep the interface working for now,
It'll be replaced by the sysfs interface which allows to step through the
hotplug state machine step by step.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-15-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine. CPU-hotplug multinstance support
is used with the nocalls() version. Maybe parts of padata_alloc() could be
moved into the online callback so that we could invoke ->startup callback for
instance and drop get_online_cpus().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-crypto@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-14-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.or
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-13-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-acpi@vger.kernel.org
Cc: rt@linutronix.de
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/20160906170457.32393-12-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine. It uses the multi instance
infrastructure of the hotplug code to handle each interface.

virtscsi_set_affinity() is removed from virtscsi_init() because
virtscsi_cpu_notif_add() (the function which registers the instance) is invoked
right after it and the cpuhp_state_add_instance() functions invokes the startup
callback on all online CPUs.

The same thing can not be applied virtscsi_cpu_notif_remove() because
virtscsi_remove_vqs() invokes virtscsi_set_affinity() with affinity = false as
argument but the old CPU_DEAD state invoked the function with affinity = true
(which does not match the DEAD callback).
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: virtualization@lists.linux-foundation.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-11-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.
Since the online target runs always on the target CPU we can drop
smp_call_function_single(). The functions is invoked with interrupts off to
keep the old calling convention. If the maintainer things that this function
can be called with interrupts enabled then it can be removed :)
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Robert Richter <rric@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: oprofile-list@lists.sf.net
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-10-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-9-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-8-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine. 
CPU_UP_CANCELED_FROZEN() is not preserved: It is only there to free memory in an
error case because it is assumed if the CPU does show up on resume it won't be
seen ever again. As per Borislav:
|IOW, you don't need mc_cpu_dead().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160907164523.46a2xnffha4bv63g@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-sh@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-6-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-5-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Tony Lindgren <tony@atomide.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Cc: linux-omap@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20160906170457.32393-4-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine so the old notifier based
cpuhotplug infrastructure can be removed.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-sh@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: rt@linutronix.de
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20160906170457.32393-3-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: rt@linutronix.de
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20160906170457.32393-2-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: rt@linutronix.de
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20160818125731.27256-17-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
I assume here that the powermac has two CPUs and so only one can go up
or down at a time. The variable smp_core99_host_open is here to ensure
that we do not try to open or close the i2c host twice if something goes
wrong and we invoke the prepare or online callback twice due to
rollback.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: rt@linutronix.de
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20160818125731.27256-16-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine. The online & down callbacks are
invoked on the target CPU so we can avoid using smp_call_function_single().
local_irq_disable() is used because smp_call_function_single() used to invoke
the function with interrupts disabled.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-15-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-14-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160824091444.brdr5zpbxjvh6n3f@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.

v1…v2: - Use only CPUHP_CPUIDLE_DEAD (requested by Daniel Lezcano)
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160824091259.ozyslcopxvbfdqzy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-11-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Neil Brown <neilb@suse.com>
Cc: linux-raid@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-10-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: netdev@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-9-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
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/20160818125731.27256-7-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: linux-mm@kvack.org
Cc: rt@linutronix.de
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20160818125731.27256-6-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: rt@linutronix.de
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: http://lkml.kernel.org/r/20160818125731.27256-5-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: rt@linutronix.de
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Link: http://lkml.kernel.org/r/20160823125319.abeapfjapf2kfezp@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine. They are installed at run time but
relay_prepare_cpu() does not need to be invoked by the boot CPU because
relay_open() was not yet invoked and there are no pools that need to be created.
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20160818125731.27256-3-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

relay essentially needs to maintain a per CPU array of channel buffer
pointers but it manually creates that array.  Instead its better to use
the per CPU constructs, provided by the kernel, to allocate & access the
array of pointer to channel buffers.
Signed-off-by: Akash Goel <akash.goel@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://lkml.kernel.org/r/1470909140-25919-1-git-send-email-akash.goel@intel.comSigned-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

We should have all names in the scheme "[subsys/]facility:state]". Fix the
core to comply.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Some compilers are unhappy with the anon union in the state array. Replace
it with a named union.

While at it align the state array initializers proper and add the missing
name tags.

Fixes: cf392d10 "cpu/hotplug: Add multi instance support"
Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: Fenguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de

When cpu_hotplug_enable() is called unbalanced w/o a preceeding
cpu_hotplug_disable() the code emits a warning, but happily decrements the
disabled counter. This causes the next operations to malfunction.

Prevent the decrement and just emit a warning.
Signed-off-by: Lianwei Wang <lianwei.wang@gmail.com>
Cc: peterz@infradead.org
Cc: linux-pm@vger.kernel.org
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/1465541008-12476-1-git-send-email-lianwei.wang@gmail.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Install the callbacks via the state machine.

The driver supports multiple instances and therefore the new
cpuhp_state_add_instance_nocalls() infrastrucure is used. The driver
currently uses get_online_cpus() to avoid missing a CPU hotplug event while
invoking virtnet_set_affinity(). This could be avoided by using
cpuhp_state_add_instance() variant which holds the hotplug lock and invokes
callback during registration. This is more or less a 1:1 conversion of the
current code.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: netdev@vger.kernel.org
Cc: Will Deacon <will.deacon@arm.com>
Cc: virtualization@lists.linux-foundation.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/1471024183-12666-7-git-send-email-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/1471024183-12666-6-git-send-email-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: rt@linutronix.de
Cc: Olof Johansson <olof@lixom.net>
Link: http://lkml.kernel.org/r/1471024183-12666-5-git-send-email-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160817171420.sdwk2qivxunzryz4@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

This patch adds the ability for a given state to have multiple
instances. Until now all states have a single instance and the startup /
teardown callback use global variables.
A few drivers need to perform a the same callbacks on multiple
"instances". Currently we have three drivers in tree which all have a
global list which they iterate over. With multi instance they support
don't need their private list and the functionality has been moved into
core code. Plus we hold the hotplug lock in core so no cpus comes/goes
while instances are registered and we do rollback in error case :)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/1471024183-12666-3-git-send-email-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

This is preparation for the following patch.
This rework here changes the arguments of cpuhp_invoke_callback(). It
passes now `state' and whether `startup' or `teardown' callback should
be invoked. The callback then is looked up by the function.

The following is a clanup of callers:
- cpuhp_issue_call() has one argument less
- struct cpuhp_cpu_state (which is used by the hotplug thread) gets also
  its callback removed. The decision if it is a single callback
  invocation moved to the `single' variable. Also a `bringup' variable
  has been added to distinguish between startup and teardown callback.
- take_cpu_down() needs to start one step earlier. We always get here
  via CPUHP_TEARDOWN_CPU callback. Before that change cpuhp_ap_states +
  CPUHP_TEARDOWN_CPU pointed to an empty entry because TEARDOWN is saved
  in bp_states for this reason. Now that we use cpuhp_get_step() to
  lookup the state we must explicitly skip it in order not to invoke it
  twice.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/1471024183-12666-2-git-send-email-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Apply upstream changes to avoid conflicts with pending patches.