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[RFC][BUG] tracer: Fails to work

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Hi Steve,

So I was hunting wabbits the other day and ftrace failed to work.

After I cursed a bit on IRC, Thomas found the below, after 'fixing' it
like so things worked enough to get the trace out.

Relying on things like this make it entirely impossible to get any trace
data out if you've wedged a CPU. Exactly the kind of situation you want
trace data for.

Please consider an appropriate change to make this happen.

---
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 95181e36891a..b09c5b955555 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4053,7 +4053,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_read_prepare);
 void
 ring_buffer_read_prepare_sync(void)
 {
-	synchronize_sched();
+//	synchronize_sched();
 }
 EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync);
 

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[RFC][BUG] tracer: Fails to work Peter Zijlstra <peterz@infradead.org> - 2016-01-28 09:10 +0100
  Re: [RFC][BUG] tracer: Fails to work Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-01-28 14:40 +0100
    Re: [RFC][BUG] tracer: Fails to work Peter Zijlstra <peterz@infradead.org> - 2016-01-28 15:00 +0100
      Re: [RFC][BUG] tracer: Fails to work Steven Rostedt <rostedt@goodmis.org> - 2016-01-28 15:20 +0100
      Re: [RFC][BUG] tracer: Fails to work Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-01-28 15:40 +0100
        Re: [RFC][BUG] tracer: Fails to work Peter Zijlstra <peterz@infradead.org> - 2016-01-28 15:50 +0100
          Re: [RFC][BUG] tracer: Fails to work Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-01-28 16:00 +0100
            Re: [RFC][BUG] tracer: Fails to work Peter Zijlstra <peterz@infradead.org> - 2016-01-28 16:40 +0100
              Re: [RFC][BUG] tracer: Fails to work Steven Rostedt <rostedt@goodmis.org> - 2016-01-28 17:00 +0100

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