perf/x86/intel/cstate: Convert Intel CSTATE to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153334.184061086@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 17 insertions, 36 deletions

diff --git a/arch/x86/events/intel/cstate.c b/arch/x86/events/intel/cstate.c
index 9ba4e4136a15..d6d7be0b3495 100644
--- a/arch/x86/events/intel/cstate.c
+++ b/arch/x86/events/intel/cstate.c
@@ -365,7 +365,7 @@ static int cstate_pmu_event_add(struct perf_event *event, int mode)
  * Check if exiting cpu is the designated reader. If so migrate the
  * events when there is a valid target available
  */
-static void cstate_cpu_exit(int cpu)
+static int cstate_cpu_exit(unsigned int cpu)
 {
         unsigned int target;
 
@@ -390,9 +390,10 @@ static void cstate_cpu_exit(int cpu)
                         perf_pmu_migrate_context(&cstate_pkg_pmu, cpu, target);
                 }
         }
+        return 0;
 }
 
-static void cstate_cpu_init(int cpu)
+static int cstate_cpu_init(unsigned int cpu)
 {
         unsigned int target;
 
@@ -414,31 +415,10 @@ static void cstate_cpu_init(int cpu)
                                  topology_core_cpumask(cpu));
         if (has_cstate_pkg && target >= nr_cpu_ids)
                 cpumask_set_cpu(cpu, &cstate_pkg_cpu_mask);
-}
 
-static int cstate_cpu_notifier(struct notifier_block *self,
-                               unsigned long action, void *hcpu)
-{
-        unsigned int cpu = (long)hcpu;
-
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_STARTING:
-                cstate_cpu_init(cpu);
-                break;
-        case CPU_DOWN_PREPARE:
-                cstate_cpu_exit(cpu);
-                break;
-        default:
-                break;
-        }
-        return NOTIFY_OK;
+        return 0;
 }
 
-static struct notifier_block cstate_cpu_nb = {
-        .notifier_call  = cstate_cpu_notifier,
-        .priority       = CPU_PRI_PERF + 1,
-};
-
 static struct pmu cstate_core_pmu = {
         .attr_groups    = core_attr_groups,
         .name           = "cstate_core",
@@ -599,18 +579,20 @@ static inline void cstate_cleanup(void)
 
 static int __init cstate_init(void)
 {
-        int cpu, err;
+        int err;
 
-        cpu_notifier_register_begin();
-        for_each_online_cpu(cpu)
-                cstate_cpu_init(cpu);
+        cpuhp_setup_state(CPUHP_AP_PERF_X86_CSTATE_STARTING,
+                          "AP_PERF_X86_CSTATE_STARTING", cstate_cpu_init,
+                          NULL);
+        cpuhp_setup_state(CPUHP_AP_PERF_X86_CSTATE_ONLINE,
+                          "AP_PERF_X86_CSTATE_ONLINE", NULL, cstate_cpu_exit);
 
         if (has_cstate_core) {
                 err = perf_pmu_register(&cstate_core_pmu, cstate_core_pmu.name, -1);
                 if (err) {
                         has_cstate_core = false;
                         pr_info("Failed to register cstate core pmu\n");
-                        goto out;
+                        return err;
                 }
         }
 
@@ -620,12 +602,10 @@ static int __init cstate_init(void)
                         has_cstate_pkg = false;
                         pr_info("Failed to register cstate pkg pmu\n");
                         cstate_cleanup();
-                        goto out;
+                        return err;
                 }
         }
-        __register_cpu_notifier(&cstate_cpu_nb);
-out:
-        cpu_notifier_register_done();
+
         return err;
 }
 
@@ -651,9 +631,8 @@ module_init(cstate_pmu_init);
 
 static void __exit cstate_pmu_exit(void)
 {
-        cpu_notifier_register_begin();
-        __unregister_cpu_notifier(&cstate_cpu_nb);
+        cpuhp_remove_state_nocalls(CPUHP_AP_PERF_X86_CSTATE_ONLINE);
+        cpuhp_remove_state_nocalls(CPUHP_AP_PERF_X86_CSTATE_STARTING);
         cstate_cleanup();
-        cpu_notifier_register_done();
 }
 module_exit(cstate_pmu_exit);
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f9399eeba263..68f4495f4988 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -26,6 +26,7 @@ enum cpuhp_state {
         CPUHP_AP_PERF_X86_STARTING,
         CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
         CPUHP_AP_PERF_X86_CQM_STARTING,
+        CPUHP_AP_PERF_X86_CSTATE_STARTING,
         CPUHP_AP_NOTIFY_STARTING,
         CPUHP_AP_ONLINE,
         CPUHP_TEARDOWN_CPU,
@@ -38,6 +39,7 @@ enum cpuhp_state {
         CPUHP_AP_PERF_X86_AMD_UNCORE_ONLINE,
         CPUHP_AP_PERF_X86_RAPL_ONLINE,
         CPUHP_AP_PERF_X86_CQM_ONLINE,
+        CPUHP_AP_PERF_X86_CSTATE_ONLINE,
         CPUHP_AP_NOTIFY_ONLINE,
         CPUHP_AP_ONLINE_DYN,
         CPUHP_AP_ONLINE_DYN_END         = CPUHP_AP_ONLINE_DYN + 30,