linux.git/kernel/cpu.c, branch v4.12-rc2

Merge branch 'linus' into locking/core, to pick up fixes

2017-04-14T08:29:40+00:00

Signed-off-by: Ingo Molnar

lockdep: Fix per-cpu static objects

2017-03-26T13:09:45+00:00

Since commit 383776fa7527 ("locking/lockdep: Handle statically initialized
PER_CPU locks properly") we try to collapse per-cpu locks into a single
class by giving them all the same key. For this key we choose the canonical
address of the per-cpu object, which would be the offset into the per-cpu
area.

This has two problems:

 - there is a case where we run !0 lock->key through static_obj() and
   expect this to pass; it doesn't for canonical pointers.

 - 0 is a valid canonical address.

Cure both issues by redefining the canonical address as the address of the
per-cpu variable on the boot CPU.

Since I didn't want to rely on CPU0 being the boot-cpu, or even existing at
all, track the boot CPU in a variable.

Fixes: 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly")
Reported-by: kernel test robot 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Borislav Petkov 
Cc: Sebastian Andrzej Siewior 
Cc: linux-mm@kvack.org
Cc: wfg@linux.intel.com
Cc: kernel test robot 
Cc: LKP 
Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner

cpu/hotplug: Serialize callback invocations proper

2017-03-14T18:19:27+00:00

The setup/remove_state/instance() functions in the hotplug core code are
serialized against concurrent CPU hotplug, but unfortunately not serialized
against themself.

As a consequence a concurrent invocation of these function results in
corruption of the callback machinery because two instances try to invoke
callbacks on remote cpus at the same time. This results in missing callback
invocations and initiator threads waiting forever on the completion.

The obvious solution to replace get_cpu_online() with cpu_hotplug_begin()
is not possible because at least one callsite calls into these functions
from a get_online_cpu() locked region.

Extend the protection scope of the cpuhp_state_mutex from solely protecting
the state arrays to cover the callback invocation machinery as well.

Fixes: 5b7aa87e0482 ("cpu/hotplug: Implement setup/removal interface")
Reported-and-tested-by: Bart Van Assche 
Signed-off-by: Sebastian Andrzej Siewior 
Cc: hpa@zytor.com
Cc: mingo@kernel.org
Cc: akpm@linux-foundation.org
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/20170314150645.g4tdyoszlcbajmna@linutronix.de
Signed-off-by: Thomas Gleixner

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:35+00:00

We are going to split  out of , which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:35+00:00

We are going to split  out of , which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:29+00:00

We are going to split  out of , which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

cpu/hotplug: Remove unused but set variable in _cpu_down()

2017-01-18T10:55:09+00:00

After the recent removal of the hotplug notifiers the variable 'hasdied' in
_cpu_down() is set but no longer read, leading to the following GCC warning
when building with 'make W=1':

  kernel/cpu.c:767:7: warning: variable ‘hasdied’ set but not used [-Wunused-but-set-variable]

Fix it by removing the variable.

Fixes: 530e9b76ae8f ("cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions")
Signed-off-by: Tobias Klauser 
Cc: Peter Zijlstra 
Cc: Sebastian Andrzej Siewior 
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20170117143501.20893-1-tklauser@distanz.ch
Signed-off-by: Thomas Gleixner

cpu/hotplug: Provide dynamic range for prepare stage

2017-01-16T12:20:05+00:00

Mathieu reported that the LTTNG modules are broken as of 4.10-rc1 due to
the removal of the cpu hotplug notifiers.

Usually I don't care much about out of tree modules, but LTTNG is widely
used in distros. There are two ways to solve that:

1) Reserve a hotplug state for LTTNG

2) Add a dynamic range for the prepare states.

While #1 is the simplest solution, #2 is the proper one as we can convert
in tree users, which do not care about ordering, to the dynamic range as
well.

Add a dynamic range which allows LTTNG to request states in the prepare
stage.

Reported-and-tested-by: Mathieu Desnoyers 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Mathieu Desnoyers 
Cc: Peter Zijlstra 
Cc: Sebastian Sewior 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701101353010.3401@nanos
Signed-off-by: Thomas Gleixner

smp/hotplug: Undo tglxs brainfart

2016-12-27T01:30:24+00:00

The attempt to prevent overwriting an active state resulted in a
disaster which effectively disables all dynamically allocated hotplug
states.

Cleanup the mess.

Fixes: dc280d936239 ("cpu/hotplug: Prevent overwriting of callbacks")
Reported-by: Markus Trippelsdorf 
Reported-by: Boris Ostrovsky 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Linus Torvalds

cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions

2016-12-25T09:47:43+00:00

hotcpu_notifier(), cpu_notifier(), __hotcpu_notifier(), __cpu_notifier(),
register_hotcpu_notifier(), register_cpu_notifier(),
__register_hotcpu_notifier(), __register_cpu_notifier(),
unregister_hotcpu_notifier(), unregister_cpu_notifier(),
__unregister_hotcpu_notifier(), __unregister_cpu_notifier()

are unused now. Remove them and all related code.

Remove also the now pointless cpu notifier error injection mechanism. The
states can be executed step by step and error rollback is the same as cpu
down, so any state transition can be tested w/o requiring the notifier
error injection.

Some CPU hotplug states are kept as they are (ab)used for hotplug state
tracking.

Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161221192112.005642358@linutronix.de
Signed-off-by: Thomas Gleixner