perf tools: Use ACCESS_ONCE() instead of volatile cast

Use ACCESS_ONCE() instead of the cast to volatile and read. This is just
a style change which is reader friendly.

Signed-off-by: Pranith Kumar <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/util/session.h

@@ -126,5 +126,5 @@ int __perf_session__set_tracepoints_handlers(struct perf_session *session,
 
 extern volatile int session_done;
 
-#define session_done()	(*(volatile int *)(&session_done))
+#define session_done()	ACCESS_ONCE(session_done)
 #endif /* __PERF_SESSION_H */