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Commit b377c2a0 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
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stop_machine: Don't do for_each_cpu() twice in queue_stop_cpus_work() 



queue_stop_cpus_work() can do everything in one for_each_cpu() loop.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: der.herr@hofr.at
Cc: paulmck@linux.vnet.ibm.com
Cc: riel@redhat.com
Cc: viro@ZenIV.linux.org.uk
Link: http://lkml.kernel.org/r/20150630012948.GA23927@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 02cb7aa9

kernel/stop_machine.c

+7 −10
Original line number Diff line number Diff line
@@ -303,22 +303,19 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask, 
	struct cpu_stop_work *work;

	unsigned int cpu;



	/* initialize works and done */

	for_each_cpu(cpu, cpumask) {

		work = &per_cpu(cpu_stopper.stop_work, cpu);

		work->fn = fn;

		work->arg = arg;

		work->done = done;

	}



	/*

	 * Disable preemption while queueing to avoid getting

	 * preempted by a stopper which might wait for other stoppers

	 * to enter @fn which can lead to deadlock.

	 */

	lg_global_lock(&stop_cpus_lock);

	for_each_cpu(cpu, cpumask)

		cpu_stop_queue_work(cpu, &per_cpu(cpu_stopper.stop_work, cpu));

	for_each_cpu(cpu, cpumask) {

		work = &per_cpu(cpu_stopper.stop_work, cpu);

		work->fn = fn;

		work->arg = arg;

		work->done = done;

		cpu_stop_queue_work(cpu, work);

	}

	lg_global_unlock(&stop_cpus_lock);

}