---

yaml
---
r: 180096
b: refs/heads/master
c: 492a74f
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 74bf4076f2ed79b5510440b72a561823a8852ec0
+refs/heads/master: 492a74f4210e15f4701422e2e1c4cd3c1e45ddae

trunk/kernel/trace/ring_buffer.c

@@ -464,6 +464,8 @@ struct ring_buffer_iter {
 	struct ring_buffer_per_cpu	*cpu_buffer;
 	unsigned long			head;
 	struct buffer_page		*head_page;
+	struct buffer_page		*cache_reader_page;
+	unsigned long			cache_read;
 	u64				read_stamp;
 };
 
@@ -2716,6 +2718,8 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
 		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;
 }
 
 /**
@@ -3066,6 +3070,15 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 	cpu_buffer = iter->cpu_buffer;
 	buffer = cpu_buffer->buffer;
 
+	/*
+	 * Check if someone performed a consuming read to
+	 * the buffer. A consuming read invalidates the iterator
+	 * and we need to reset the iterator in this case.
+	 */
+	if (unlikely(iter->cache_read != cpu_buffer->read ||
+		     iter->cache_reader_page != cpu_buffer->reader_page))
+		rb_iter_reset(iter);
+
  again:
 	/*
 	 * We repeat when a timestamp is encountered.