tracing: generate RCU warnings even when tracepoints are disabled

tracing: generate RCU warnings even when tracepoints are disabled

Dave Jones reported seeing a bug from one of my TLB tracepoints:

	http://lkml.kernel.org/r/20140806181801[email protected]

I've been running these patches for months and never saw this.
But, a big chunk of my testing, especially with all the debugging
enabled, was in a vm where intel_idle doesn't work.  On the
systems where I was using intel_idle, I never had lockdep enabled
and this tracepoint on at the same time.

This patch ensures that whenever we have lockdep available, we do
_some_ RCU activity at the site of the tracepoint, despite
whether the tracepoint's condition matches or even if the
tracepoint itself is completely disabled.  This is a bit of a
hack, but it is pretty self-contained.

I confirmed that with this patch plus lockdep I get the same
splat as Dave Jones did, but without enabling the tracepoint
explicitly.

Link: http://lkml.kernel.org/p/[email protected]
Signed-off-by: Dave Hansen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Jones <[email protected]>,
Cc: [email protected]
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>