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authorLinus Torvalds <torvalds@linux-foundation.org>2010-12-28 15:54:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-12-28 15:54:24 -0800
commit6f7f41851cc4508b672ab71dd48a154712faf15c (patch)
tree7eecd1c529e60c220a4376a51f47f83d77a89da2
parent82cd19cd93727d494c530ddd6a7338033c3fd86e (diff)
parente1e359273576ee8fe27021356b064c772ed29af3 (diff)
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
-rw-r--r--kernel/trace/ring_buffer.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9ed509a015d8..bd1c35a4fbcc 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3853,6 +3853,13 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
/* 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 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
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);