tracing/events: don't use wake up for events
Impact: fix hard-lockup with sched switch events
Some ftrace events, such as sched wakeup, can be traced
while the runqueue lock is hold. Since they are using
trace_current_buffer_unlock_commit(), they call wake_up()
which can try to grab the runqueue lock too, resulting in
a deadlock.
Now for all event, we call a new helper:
trace_nowake_buffer_unlock_commit() which do pretty the same than
trace_current_buffer_unlock_commit() except than it doesn't call
trace_wake_up().
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f267723..54fd9bc 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -483,6 +483,8 @@
unsigned long flags, int pc);
void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
unsigned long flags, int pc);
+void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event,
+ unsigned long flags, int pc);
struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
struct trace_array_cpu *data);