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27 March 2024, 02:37:15 UTC
Revision e1e359273576ee8fe27021356b064c772ed29af3 authored by David Sharp on 23 December 2010, 00:38:24 UTC, committed by Steven Rostedt on 23 December 2010, 17:09:30 UTC 
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 <dhsharp@google.com>
LKML-Reference: <1293064704-8101-1-git-send-email-dhsharp@google.com>
LKML-Reference: <AANLkTin7nLrRPc9qGjdjHbeVDDWiJjAiYyb-L=gH85bx@mail.gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
1 parent 2ce494a
History
Tip revision: e1e359273576ee8fe27021356b064c772ed29af3 authored by David Sharp on 23 December 2010, 00:38:24 UTC
ring_buffer: Off-by-one and duplicate events in ring_buffer_read_page
Tip revision: e1e3592
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