Commit 210e2133 authored May 24, 2017 by Sebastian Andrzej Siewior Committed by Thomas Gleixner May 26, 2017

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



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

parent f9a69931

kernel/cpu.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -701,7 +701,7 @@ static int takedown_cpu(unsigned int cpu)
		/*
		* 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) {
		/* CPU refused to die */
		irq_unlock_sparse();

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