perf evsel: Add a backpointer to the evlist a evsel is in

So that functions that deal primarily with an evsel to access
information that concerns the whole evlist it is in.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1440677263-21954-5-git-send-email-kan.liang@intel.com
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 93ac6b1..298e6bb 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -60,6 +60,9 @@
 
 /** struct perf_evsel - event selector
  *
+ * @evlist - evlist this evsel is in, if it is in one.
+ * @node - To insert it into evlist->entries or in other list_heads, say in
+ *         the event parsing routines.
  * @name - Can be set to retain the original event name passed by the user,
  *         so that when showing results in tools such as 'perf stat', we
  *         show the name used, not some alias.
@@ -73,6 +76,7 @@
  */
 struct perf_evsel {
 	struct list_head	node;
+	struct perf_evlist	*evlist;
 	struct perf_event_attr	attr;
 	char			*filter;
 	struct xyarray		*fd;