Merge tag 'sunxi-dt-for-3.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git...

[firefly-linux-kernel-4.4.55.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 925f629658d64df9ba398482986423560db1d3d3..afb04b9b818a473f8b38e0aa94ee12ad84c44d1a 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1968,7 +1968,7 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta)
 
 /**
  * rb_update_event - update event type and data
- * @event: the even to update
+ * @event: the event to update
  * @type: the type of event
  * @length: the size of the event field in the ring buffer
  *
@@ -3341,21 +3341,16 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
        struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
 
        /* Iterator usage is expected to have record disabled */
-       if (list_empty(&cpu_buffer->reader_page->list)) {
-               iter->head_page = rb_set_head_page(cpu_buffer);
-               if (unlikely(!iter->head_page))
-                       return;
-               iter->head = iter->head_page->read;
-       } else {
-               iter->head_page = cpu_buffer->reader_page;
-               iter->head = cpu_buffer->reader_page->read;
-       }
+       iter->head_page = cpu_buffer->reader_page;
+       iter->head = cpu_buffer->reader_page->read;
+
+       iter->cache_reader_page = iter->head_page;
+       iter->cache_read = iter->head;
+
        if (iter->head)
                iter->read_stamp = cpu_buffer->read_stamp;
        else
                iter->read_stamp = iter->head_page->page->time_stamp;
-       iter->cache_reader_page = cpu_buffer->reader_page;
-       iter->cache_read = cpu_buffer->read;
 }
 
 /**
@@ -3748,12 +3743,14 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
                return NULL;
 
        /*
-        * We repeat when a time extend is encountered.
-        * Since the time extend is always attached to a data event,
-        * we should never loop more than once.
-        * (We never hit the following condition more than twice).
+        * We repeat when a time extend is encountered or we hit
+        * the end of the page. Since the time extend is always attached
+        * to a data event, we should never loop more than three times.
+        * Once for going to next page, once on time extend, and
+        * finally once to get the event.
+        * (We never hit the following condition more than thrice).
         */
-       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2))
+       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3))
                return NULL;
 
        if (rb_per_cpu_empty(cpu_buffer))