1 files changed, 20 insertions, 1 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 733c61636f0d..15e58d4ea035 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3587,6 +3587,19 @@ static int perf_event_read_one(struct perf_event *event,
         return n * sizeof(u64);
 }
 
+static bool is_event_hup(struct perf_event *event)
+{
+        bool no_children;
+
+        if (event->state != PERF_EVENT_STATE_EXIT)
+                return false;
+
+        mutex_lock(&event->child_mutex);
+        no_children = list_empty(&event->child_list);
+        mutex_unlock(&event->child_mutex);
+        return no_children;
+}
+
 /*
  * Read the performance event - simple non blocking version for now
  */
@@ -3632,7 +3645,7 @@ static unsigned int perf_poll(struct file *file, poll_table *wait)
 
         poll_wait(file, &event->waitq, wait);
 
-        if (event->state == PERF_EVENT_STATE_EXIT)
+        if (is_event_hup(event))
                 return events;
 
         /*
@@ -7580,6 +7593,12 @@ static void sync_child_event(struct perf_event *child_event,
         mutex_unlock(&parent_event->child_mutex);
 
         /*
+         * Make sure user/parent get notified, that we just
+         * lost one event.
+         */
+        perf_event_wakeup(parent_event);
+
+        /*
          * Release the parent event, if this was the last
          * reference to it.
          */