1 files changed, 13 insertions, 26 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index c792ea893b0..342eacc4baa 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -321,9 +321,10 @@ struct buffer_data_page {
 };
 
 struct buffer_page {
+	struct list_head list;		/* list of buffer pages */
 	local_t		 write;		/* index for next write */
 	unsigned	 read;		/* index for next read */
-	struct list_head list;		/* list of free pages */
+	local_t		 entries;	/* entries on this page */
 	struct buffer_data_page *page;	/* Actual data page */
 };
 
@@ -977,30 +978,6 @@ static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer)
 	return rb_page_commit(cpu_buffer->head_page);
 }
 
-/*
- * When the tail hits the head and the buffer is in overwrite mode,
- * the head jumps to the next page and all content on the previous
- * page is discarded. But before doing so, we update the overrun
- * variable of the buffer.
- */
-static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer)
-{
-	struct ring_buffer_event *event;
-	unsigned long head;
-
-	for (head = 0; head < rb_head_size(cpu_buffer);
-	     head += rb_event_length(event)) {
-
-		event = __rb_page_index(cpu_buffer->head_page, head);
-		if (RB_WARN_ON(cpu_buffer, rb_null_event(event)))
-			return;
-		/* Only count data entries */
-		if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
-			continue;
-		cpu_buffer->overrun++;
-	}
-}
-
 static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer,
 			       struct buffer_page **bpage)
 {
@@ -1253,7 +1230,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 			/* tail_page has not moved yet? */
 			if (tail_page == cpu_buffer->tail_page) {
 				/* count overflows */
-				rb_update_overflow(cpu_buffer);
+				cpu_buffer->overrun +=
+					local_read(&head_page->entries);
 
 				rb_inc_page(cpu_buffer, &head_page);
 				cpu_buffer->head_page = head_page;
@@ -1268,6 +1246,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 		 */
 		if (tail_page == cpu_buffer->tail_page) {
 			local_set(&next_page->write, 0);
+			local_set(&next_page->entries, 0);
 			local_set(&next_page->page->commit, 0);
 			cpu_buffer->tail_page = next_page;
 
@@ -1313,6 +1292,10 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 	event = __rb_page_index(tail_page, tail);
 	rb_update_event(event, type, length);
 
+	/* The passed in type is zero for DATA */
+	if (likely(!type))
+		local_inc(&tail_page->entries);
+
 	/*
 	 * If this is a commit and the tail is zero, then update
 	 * this page's time stamp.
@@ -2183,6 +2166,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
 	cpu_buffer->reader_page->list.prev = reader->list.prev;
 
 	local_set(&cpu_buffer->reader_page->write, 0);
+	local_set(&cpu_buffer->reader_page->entries, 0);
 	local_set(&cpu_buffer->reader_page->page->commit, 0);
 
 	/* Make the reader page now replace the head */
@@ -2629,6 +2613,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 	cpu_buffer->head_page
 		= list_entry(cpu_buffer->pages.next, struct buffer_page, list);
 	local_set(&cpu_buffer->head_page->write, 0);
+	local_set(&cpu_buffer->head_page->entries, 0);
 	local_set(&cpu_buffer->head_page->page->commit, 0);
 
 	cpu_buffer->head_page->read = 0;
@@ -2638,6 +2623,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 
 	INIT_LIST_HEAD(&cpu_buffer->reader_page->list);
 	local_set(&cpu_buffer->reader_page->write, 0);
+	local_set(&cpu_buffer->reader_page->entries, 0);
 	local_set(&cpu_buffer->reader_page->page->commit, 0);
 	cpu_buffer->reader_page->read = 0;
 
@@ -2996,6 +2982,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
 		bpage = reader->page;
 		reader->page = *data_page;
 		local_set(&reader->write, 0);
+		local_set(&reader->entries, 0);
 		reader->read = 0;
 		*data_page = bpage;