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

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 8c00dc09a5d2cf41e0e0af5f6eb76577f4f0df09..2521f771f2f51be3f3035e09d8d181bccadf15bb 100644 (file)
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -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,
-                         "perf/x86/cqm:starting",
-                         intel_cqm_cpu_starting, NULL);
-       cpuhp_setup_state(CPUHP_AP_PERF_X86_CQM_ONLINE, "perf/x86/cqm:online",
-                         NULL, intel_cqm_cpu_exit);
-
+       cpuhp_setup_state_cpuslocked(CPUHP_AP_PERF_X86_CQM_STARTING,
+                                    "perf/x86/cqm:starting",
+                                    intel_cqm_cpu_starting, NULL);
+       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);