Commit b118415b authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar

tracing/events: don't discard an event after commit

When we want to filter an event, the filter test is done after
the event is commited to the ring-buffer to be discarded later if
needed.

But a reader could be reading this event while we are trying to discard
it. Other kind of racy events can even happen because the event is
commited and can be read and/or consumed.

What we want is to discard the event before committing it.
Reported-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1237763919-21505-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7e6ea92d
...@@ -222,10 +222,11 @@ static void ftrace_raw_event_##call(proto) \ ...@@ -222,10 +222,11 @@ static void ftrace_raw_event_##call(proto) \
\ \
assign; \ assign; \
\ \
trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
\
if (call->preds && !filter_match_preds(call, entry)) \ if (call->preds && !filter_match_preds(call, entry)) \
ring_buffer_event_discard(event); \ ring_buffer_event_discard(event); \
\
trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
\
} \ } \
\ \
static int ftrace_raw_reg_event_##call(void) \ static int ftrace_raw_reg_event_##call(void) \
......
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