perf: Fix perf_event_validate_size() lockdep splat

[linux-2.6-block.git] / kernel / events / core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c9d123e13b57958bc9532ebdc45f17b13830327a..9efd0d7775e7ce400a1c966ba09af73ec3887f3d 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1947,6 +1947,16 @@ static bool perf_event_validate_size(struct perf_event *event)
                                   group_leader->nr_siblings + 1) > 16*1024)
                return false;
 
+       /*
+        * When creating a new group leader, group_leader->ctx is initialized
+        * after the size has been validated, but we cannot safely use
+        * for_each_sibling_event() until group_leader->ctx is set. A new group
+        * leader cannot have any siblings yet, so we can safely skip checking
+        * the non-existent siblings.
+        */
+       if (event == group_leader)
+               return true;
+
        for_each_sibling_event(sibling, group_leader) {
                if (__perf_event_read_size(sibling->attr.read_format,
                                           group_leader->nr_siblings + 1) > 16*1024)