Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
ring_buffer: Off-by-one and duplicate events in ring_buffer_read_page
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9ed509a..bd1c35a 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3853,6 +3853,13 @@
/* Need to copy one event at a time */
do {
+ /* We need the size of one event, because
+ * rb_advance_reader only advances by one event,
+ * whereas rb_event_ts_length may include the size of
+ * one or two events.
+ * We have already ensured there's enough space if this
+ * is a time extend. */
+ size = rb_event_length(event);
memcpy(bpage->data + pos, rpage->data + rpos, size);
len -= size;
@@ -3867,7 +3874,7 @@
event = rb_reader_event(cpu_buffer);
/* Always keep the time extend and data together */
size = rb_event_ts_length(event);
- } while (len > size);
+ } while (len >= size);
/* update bpage */
local_set(&bpage->commit, pos);
