tracepoints: Fix documentation of RCU lockdep checks

commit a15920be upstream.

The documentation on top of __DECLARE_TRACE() does not match its
implementation since the condition check has been added to the
RCU lockdep checks. Update the documentation to match its
implementation.

Link: http://lkml.kernel.org/r/1446504164-21563-1-git-send-email-mathieu.desnoyers@efficios.com

CC: Dave Hansen <dave@sr71.net>
Fixes: a05d59a5 "tracing: Add condition check to RCU lockdep checks"
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

include/linux/tracepoint.h

@@ -167,10 +167,11 @@ extern void syscall_unregfunc(void);
  * structure. Force alignment to the same alignment as the section start.
  *
  * When lockdep is enabled, we make sure to always do the RCU portions of
- * the tracepoint code, regardless of whether tracing is on or we match the
- * condition.  This lets us find RCU issues triggered with tracepoints even
- * when this tracepoint is off.  This code has no purpose other than poking
- * RCU a bit.
+ * the tracepoint code, regardless of whether tracing is on. However,
+ * don't check if the condition is false, due to interaction with idle
+ * instrumentation. This lets us find RCU issues triggered with tracepoints
+ * even when this tracepoint is off. This code has no purpose other than
+ * poking RCU a bit.
  */
 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
 	extern struct tracepoint __tracepoint_##name;			\