| Date | Wed, 24 May 2017 10:15:28 +0200 | From | Thomas Gleixner <> | Subject | [patch V3 17/32] cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu() |
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org>
--- kernel/cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -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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