x86/oprofile/nmi: Convert 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>
Cc: Robert Richter <rric@kernel.org>
Cc: oprofile-list@lists.sf.net
Cc: rt@linuxtronix.de
Link: http://lkml.kernel.org/r/20161117183541.8588-20-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 18 insertions, 43 deletions

diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index c39172cd6c87..ffdbc4836b4f 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -339,10 +339,11 @@ fail:
         return 0;
 }
 
-static void nmi_cpu_setup(void *dummy)
+static void nmi_cpu_setup(void)
 {
         int cpu = smp_processor_id();
         struct op_msrs *msrs = &per_cpu(cpu_msrs, cpu);
+
         nmi_cpu_save_registers(msrs);
         raw_spin_lock(&oprofilefs_lock);
         model->setup_ctrs(model, msrs);
@@ -369,7 +370,7 @@ static void nmi_cpu_restore_registers(struct op_msrs *msrs)
         }
 }
 
-static void nmi_cpu_shutdown(void *dummy)
+static void nmi_cpu_shutdown(void)
 {
         unsigned int v;
         int cpu = smp_processor_id();
@@ -387,24 +388,26 @@ static void nmi_cpu_shutdown(void *dummy)
         nmi_cpu_restore_registers(msrs);
 }
 
-static void nmi_cpu_up(void)
+static int nmi_cpu_online(unsigned int cpu)
 {
         local_irq_disable();
         if (nmi_enabled)
-                nmi_cpu_setup(NULL);
+                nmi_cpu_setup();
         if (ctr_running)
                 nmi_cpu_start(NULL);
         local_irq_enable();
+        return 0;
 }
 
-static void nmi_cpu_down(void)
+static int nmi_cpu_down_prep(unsigned int cpu)
 {
         local_irq_disable();
         if (ctr_running)
                 nmi_cpu_stop(NULL);
         if (nmi_enabled)
-                nmi_cpu_shutdown(NULL);
+                nmi_cpu_shutdown();
         local_irq_enable();
+        return 0;
 }
 
 static int nmi_create_files(struct dentry *root)
@@ -437,24 +440,7 @@ static int nmi_create_files(struct dentry *root)
         return 0;
 }
 
-static int oprofile_cpu_notifier(struct notifier_block *b, unsigned long action,
-                                 void *data)
-{
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_DOWN_FAILED:
-        case CPU_ONLINE:
-                nmi_cpu_up();
-                break;
-        case CPU_DOWN_PREPARE:
-                nmi_cpu_down();
-                break;
-        }
-        return NOTIFY_DONE;
-}
-
-static struct notifier_block oprofile_cpu_nb = {
-        .notifier_call = oprofile_cpu_notifier
-};
+static enum cpuhp_state cpuhp_nmi_online;
 
 static int nmi_setup(void)
 {
@@ -497,20 +483,17 @@ static int nmi_setup(void)
         if (err)
                 goto fail;
 
-        cpu_notifier_register_begin();
-
-        /* Use get/put_online_cpus() to protect 'nmi_enabled' */
-        get_online_cpus();
         nmi_enabled = 1;
         /* make nmi_enabled visible to the nmi handler: */
         smp_mb();
-        on_each_cpu(nmi_cpu_setup, NULL, 1);
-        __register_cpu_notifier(&oprofile_cpu_nb);
-        put_online_cpus();
-
-        cpu_notifier_register_done();
-
+        err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/oprofile:online",
+                                nmi_cpu_online, nmi_cpu_down_prep);
+        if (err < 0)
+                goto fail_nmi;
+        cpuhp_nmi_online = err;
         return 0;
+fail_nmi:
+        unregister_nmi_handler(NMI_LOCAL, "oprofile");
 fail:
         free_msrs();
         return err;
@@ -520,17 +503,9 @@ static void nmi_shutdown(void)
 {
         struct op_msrs *msrs;
 
-        cpu_notifier_register_begin();
-
-        /* Use get/put_online_cpus() to protect 'nmi_enabled' & 'ctr_running' */
-        get_online_cpus();
-        on_each_cpu(nmi_cpu_shutdown, NULL, 1);
+        cpuhp_remove_state(cpuhp_nmi_online);
         nmi_enabled = 0;
         ctr_running = 0;
-        __unregister_cpu_notifier(&oprofile_cpu_nb);
-        put_online_cpus();
-
-        cpu_notifier_register_done();
 
         /* make variables visible to the nmi handler: */
         smp_mb();