ring_buffer: Off-by-one and duplicate events in ring_buffer_read_page

Fix two related problems in the event-copying loop of
ring_buffer_read_page.

The loop condition for copying events is off-by-one.
"len" is the remaining space in the caller-supplied page.
"size" is the size of the next event (or two events).
If len == size, then there is just enough space for the next event.

size was set to rb_event_ts_length, which may include the size of two
events if the first event is a time-extend, in order to assure time-
extends are kept together with the event after it. However,
rb_advance_reader always advances by one event. This would result in the
event after any time-extend being duplicated. Instead, get the size of
a single event for the memcpy, but use rb_event_ts_length for the loop
condition.

Signed-off-by: David Sharp <[email protected]>
LKML-Reference: <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

0 files changed, 0 insertions, 0 deletions