perf_counter: initialize the per-cpu context earlier

percpu scheduling for perfcounters wants to take the context lock,
but that lock first needs to be initialized. Currently it is an
early_initcall() - but that is too late, the task tick runs much
sooner than that.

Call it explicitly from the scheduler init sequence instead.

[ Impact: fix access-before-init crash ]

LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 5 insertions, 5 deletions

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index b9679c36bcc2..fcdafa234a5d 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -3265,15 +3265,12 @@ static struct notifier_block __cpuinitdata perf_cpu_nb = {
         .notifier_call          = perf_cpu_notify,
 };
 
-static int __init perf_counter_init(void)
+void __init perf_counter_init(void)
 {
         perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
                         (void *)(long)smp_processor_id());
         register_cpu_notifier(&perf_cpu_nb);
-
-        return 0;
 }
-early_initcall(perf_counter_init);
 
 static ssize_t perf_show_reserve_percpu(struct sysdev_class *class, char *buf)
 {
diff --git a/kernel/sched.c b/kernel/sched.c
index 2f600e30dcf0..a728976a3a6c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -39,6 +39,7 @@
 #include <linux/completion.h>
 #include <linux/kernel_stat.h>
 #include <linux/debug_locks.h>
+#include <linux/perf_counter.h>
 #include <linux/security.h>
 #include <linux/notifier.h>
 #include <linux/profile.h>
@@ -8996,7 +8997,7 @@ void __init sched_init(void)
                  * 1024) and two child groups A0 and A1 (of weight 1024 each),
                  * then A0's share of the cpu resource is:
                  *
-                 *      A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
+                 *      A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
                  *
                  * We achieve this by letting init_task_group's tasks sit
                  * directly in rq->cfs (i.e init_task_group->se[] = NULL).
@@ -9097,6 +9098,8 @@ void __init sched_init(void)
         alloc_bootmem_cpumask_var(&cpu_isolated_map);
 #endif /* SMP */
 
+        perf_counter_init();
+
         scheduler_running = 1;
 }