linux-toradex.git/kernel/smpboot.c, branch v5.3-rc6

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

smpboot: Remove cpumask from the API

2018-07-03T07:20:44+00:00

Now that the sole use of the whole smpboot_*cpumask() API is gone,
remove it.

Suggested-by: Oleg Nesterov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

watchdog/core, powerpc: Lock cpus across reconfiguration

2017-10-04T08:53:54+00:00

Instead of dropping the cpu hotplug lock after stopping NMI watchdog and
threads and reaquiring for restart, the code and the protection rules
become more obvious when holding cpu hotplug lock across the full
reconfiguration.

Suggested-by: Linus Torvalds 
Signed-off-by: Thomas Gleixner 
Acked-by: Michael Ellerman 
Cc: Peter Zijlstra 
Cc: Don Zickus 
Cc: Benjamin Herrenschmidt 
Cc: Nicholas Piggin 
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1710022105570.2114@nanos

smpboot/threads, watchdog/core: Avoid runtime allocation

2017-09-14T09:41:06+00:00

smpboot_update_cpumask_threads_percpu() allocates a temporary cpumask at
runtime. This is suboptimal because the call site needs more code size for
proper error handling than a statically allocated temporary mask requires
data size.

Add static temporary cpumask. The function is globaly serialized, so no
further protection required.

Remove the half baken error handling in the watchdog code and get rid of
the export as there are no in tree modular users of that function.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Don Zickus 
Cc: Andrew Morton 
Cc: Borislav Petkov 
Cc: Chris Metcalf 
Cc: Linus Torvalds 
Cc: Nicholas Piggin 
Cc: Peter Zijlstra 
Cc: Sebastian Siewior 
Cc: Ulrich Obergfell 
Link: http://lkml.kernel.org/r/20170912194147.297288838@linutronix.de
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

kthread/smpboot: do not park in kthread_create_on_cpu()

2016-10-11T22:06:33+00:00

kthread_create_on_cpu() was added by the commit 2a1d446019f9a5983e
("kthread: Implement park/unpark facility").  It is currently used only
when enabling new CPU.  For this purpose, the newly created kthread has to
be parked.

The CPU binding is a bit tricky.  The kthread is parked when the CPU has
not been allowed yet.  And the CPU is bound when the kthread is unparked.

The function would be useful for more per-CPU kthreads, e.g.
bnx2fc_thread, fcoethread.  For this purpose, the newly created kthread
should stay in the uninterruptible state.

This patch moves the parking into smpboot.  It binds the thread already
when created.  Then the function might be used universally.  Also the
behavior is consistent with kthread_create() and kthread_create_on_node().

Link: http://lkml.kernel.org/r/1470754545-17632-4-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek 
Reviewed-by: Thomas Gleixner 
Cc: Oleg Nesterov 
Cc: Tejun Heo 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: "Paul E. McKenney" 
Cc: Josh Triplett 
Cc: Jiri Kosina 
Cc: Borislav Petkov 
Cc: Michal Hocko 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Revert "sched/core: Do not use smp_processor_id() with preempt enabled in smpboot_thread_fn()"

2016-10-04T07:55:57+00:00

This reverts commit 4fa5cd5245b627db88c9ca08ae442373b02596b4.

The original change widens a preempt-off section, to avoid a seemingly unsafe
smp_processor_id() use.

During review I overlooked two facts:

 - The code to calls a non-trivial function callback:

                                ht->park(td->cpu);

   ... which might (and does occasionally) sleep, triggering the warning.

 - More importantly, as pointed out by Peter Zijlstra, using
   smp_processor_id() in that context is safe, if it's done from
   a kernel thread that is pinned to a single CPU - which is the
   case here.

So revert to the original code that enables preemption sooner.

Reported-by: kernel test robot 
Acked-by: Peter Zijlstra 
Cc: Con Kolivas 
Cc: Alfred Chen 
Link: http://lkml.kernel.org/r/20160930015102.GB20189@yexl-desktop
Signed-off-by: Ingo Molnar

sched/core: Do not use smp_processor_id() with preempt enabled in smpboot_thread_fn()

2016-09-22T10:28:00+00:00

We should not be using smp_processor_id() with preempt enabled.

Bug identified and fix provided by Alfred Chen.

Reported-by: Alfred Chen 
Signed-off-by: Con Kolivas 
Cc: Alfred Chen 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/2042051.3vvUWIM0vs@hex
Signed-off-by: Ingo Molnar

cpu/hotplug: Unpark smpboot threads from the state machine

2016-03-01T19:36:56+00:00

Handle the smpboot threads in the state machine.

Signed-off-by: Thomas Gleixner 
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel 
Cc: Rafael Wysocki 
Cc: "Srivatsa S. Bhat" 
Cc: Peter Zijlstra 
Cc: Arjan van de Ven 
Cc: Sebastian Siewior 
Cc: Rusty Russell 
Cc: Steven Rostedt 
Cc: Oleg Nesterov 
Cc: Tejun Heo 
Cc: Andrew Morton 
Cc: Paul McKenney 
Cc: Linus Torvalds 
Cc: Paul Turner 
Link: http://lkml.kernel.org/r/20160226182341.295777684@linutronix.de
Signed-off-by: Thomas Gleixner

stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()

2015-10-20T08:23:55+00:00

1. Change smpboot_unpark_thread() to check ->selfparking, just
   like smpboot_park_thread() does.

2. Introduce stop_machine_unpark() which sets ->enabled and calls
   kthread_unpark().

3. Change smpboot_thread_call() and cpu_stop_init() to call
   stop_machine_unpark() by hand.

This way:

    - IMO the ->selfparking logic becomes more consistent.

    - We can kill the smp_hotplug_thread->pre_unpark() method.

    - We can easily unpark the stopper thread earlier. Say, we
      can move stop_machine_unpark() from smpboot_thread_call()
      to sched_cpu_active() as Peter suggests.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: heiko.carstens@de.ibm.com
Link: http://lkml.kernel.org/r/20151009160049.GA10166@redhat.com
Signed-off-by: Ingo Molnar