Merge branch 'for-tip' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile into perf/urgent

1 files changed, 10 insertions, 4 deletions

diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index cf9750004a08..68894fdc034b 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -112,8 +112,10 @@ static void nmi_cpu_start(void *dummy)
 static int nmi_start(void)
 {
         get_online_cpus();
-        on_each_cpu(nmi_cpu_start, NULL, 1);
         ctr_running = 1;
+        /* make ctr_running visible to the nmi handler: */
+        smp_mb();
+        on_each_cpu(nmi_cpu_start, NULL, 1);
         put_online_cpus();
         return 0;
 }
@@ -504,15 +506,18 @@ static int nmi_setup(void)
 
         nmi_enabled = 0;
         ctr_running = 0;
-        barrier();
+        /* make variables visible to the nmi handler: */
+        smp_mb();
         err = register_die_notifier(&profile_exceptions_nb);
         if (err)
                 goto fail;
 
         get_online_cpus();
         register_cpu_notifier(&oprofile_cpu_nb);
-        on_each_cpu(nmi_cpu_setup, NULL, 1);
         nmi_enabled = 1;
+        /* make nmi_enabled visible to the nmi handler: */
+        smp_mb();
+        on_each_cpu(nmi_cpu_setup, NULL, 1);
         put_online_cpus();
 
         return 0;
@@ -531,7 +536,8 @@ static void nmi_shutdown(void)
         nmi_enabled = 0;
         ctr_running = 0;
         put_online_cpus();
-        barrier();
+        /* make variables visible to the nmi handler: */
+        smp_mb();
         unregister_die_notifier(&profile_exceptions_nb);
         msrs = &get_cpu_var(cpu_msrs);
         model->shutdown(msrs);