Commit 04b247c2 authored May 24, 2017 by Sebastian Andrzej Siewior Committed by Thomas Gleixner May 26, 2017

perf/x86/intel/cqm: Use cpuhp_setup_state_cpuslocked()



intel_cqm_init() holds get_online_cpus() while registerring the hotplug
callbacks.

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

Use cpuhp_setup_state_cpuslocked() to avoid the nested call. Convert
*_online_cpus() to the new interfaces while at it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081548.075604046@linutronix.de

parent e9f5d63f

arch/x86/events/intel/cqm.c

+8 −8

Original line number	Diff line number	Diff line
		@@ -1682,7 +1682,7 @@ static int __init intel_cqm_init(void)
		*
		* Also, check that the scales match on all cpus.
		*/
		get_online_cpus();
		cpus_read_lock();
		for_each_online_cpu(cpu) {
		struct cpuinfo_x86 *c = &cpu_data(cpu);

		@@ -1746,14 +1746,14 @@ static int __init intel_cqm_init(void)
		* Setup the hot cpu notifier once we are sure cqm
		* is enabled to avoid notifier leak.
		*/
		cpuhp_setup_state(CPUHP_AP_PERF_X86_CQM_STARTING,
		cpuhp_setup_state_cpuslocked(CPUHP_AP_PERF_X86_CQM_STARTING,
		"perf/x86/cqm:starting",
		intel_cqm_cpu_starting, NULL);
		cpuhp_setup_state(CPUHP_AP_PERF_X86_CQM_ONLINE, "perf/x86/cqm:online",
		cpuhp_setup_state_cpuslocked(CPUHP_AP_PERF_X86_CQM_ONLINE,
		"perf/x86/cqm:online",
		NULL, intel_cqm_cpu_exit);

		out:
		put_online_cpus();
		cpus_read_unlock();

		if (ret) {
		kfree(str);