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cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu()

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takedown_cpu() is a cpu hotplug function invoking stop_machine(). The cpu
hotplug machinery holds the hotplug lock for write.

stop_machine() invokes get_online_cpus() as well. This is correct, but
prevents the conversion of the hotplug locking to a percpu rwsem.

Use stop_machine_cpuslocked() to avoid the nested call.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081548.423292433@linutronix.de
This commit is contained in:
Sebastian Andrzej Siewior 2017-05-24 10:15:28 +02:00 committed by Thomas Gleixner
parent f9a69931c3
commit 210e21331f
1 changed files with 1 additions and 1 deletions
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2
kernel/cpu.c
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@ -701,7 +701,7 @@ static int takedown_cpu(unsigned int cpu)
/* /*
* So now all preempt/rcu users must observe !cpu_active(). * So now all preempt/rcu users must observe !cpu_active().
*/ */
err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu)); err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
if (err) { if (err) {
/* CPU refused to die */ /* CPU refused to die */
irq_unlock_sparse(); irq_unlock_sparse();