perf: Fix cgroup vs jump_label problem

Li Zefan reported that the jump label code sleeps and we're calling it
under a spinlock, *fail* ;-)

Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 13 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 193b1900e64f..ed253aa24ba4 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -820,16 +820,8 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx)
                 list_add_tail(&event->group_entry, list);
         }
 
-        if (is_cgroup_event(event)) {
+        if (is_cgroup_event(event))
                 ctx->nr_cgroups++;
-                /*
-                 * one more event:
-                 * - that has cgroup constraint on event->cpu
-                 * - that may need work on context switch
-                 */
-                atomic_inc(&per_cpu(perf_cgroup_events, event->cpu));
-                jump_label_inc(&perf_sched_events);
-        }
 
         list_add_rcu(&event->event_entry, &ctx->event_list);
         if (!ctx->nr_events)
@@ -957,11 +949,8 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
 
         event->attach_state &= ~PERF_ATTACH_CONTEXT;
 
-        if (is_cgroup_event(event)) {
+        if (is_cgroup_event(event))
                 ctx->nr_cgroups--;
-                atomic_dec(&per_cpu(perf_cgroup_events, event->cpu));
-                jump_label_dec(&perf_sched_events);
-        }
 
         ctx->nr_events--;
         if (event->attr.inherit_stat)
@@ -2903,6 +2892,10 @@ static void free_event(struct perf_event *event)
                         atomic_dec(&nr_task_events);
                 if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
                         put_callchain_buffers();
+                if (is_cgroup_event(event)) {
+                        atomic_dec(&per_cpu(perf_cgroup_events, event->cpu));
+                        jump_label_dec(&perf_sched_events);
+                }
         }
 
         if (event->buffer) {
@@ -6478,6 +6471,13 @@ SYSCALL_DEFINE5(perf_event_open,
                 err = perf_cgroup_connect(pid, event, &attr, group_leader);
                 if (err)
                         goto err_alloc;
+                /*
+                 * one more event:
+                 * - that has cgroup constraint on event->cpu
+                 * - that may need work on context switch
+                 */
+                atomic_inc(&per_cpu(perf_cgroup_events, event->cpu));
+                jump_label_inc(&perf_sched_events);
         }
 
         /*