perf evlist: Introduce evsel list accessors

To replace the longer list_entry constructs for things that are widely
used:

	perf_evlist__{first,last}(evlist)
	perf_evsel__next(evsel)

Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-ng7azq26wg1jd801qqpcozwp@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 7fe677e..2ed2557 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -5,6 +5,7 @@
 #include <stdio.h>
 #include "../perf.h"
 #include "event.h"
+#include "evsel.h"
 #include "util.h"
 #include <unistd.h>
 
@@ -41,8 +42,6 @@
 	void	   *handler;
 };
 
-struct perf_evsel;
-
 struct perf_evlist *perf_evlist__new(struct cpu_map *cpus,
 				     struct thread_map *threads);
 void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
@@ -121,17 +120,27 @@
 void __perf_evlist__set_leader(struct list_head *list);
 void perf_evlist__set_leader(struct perf_evlist *evlist);
 
-u64 perf_evlist__sample_type(const struct perf_evlist *evlist);
-bool perf_evlist__sample_id_all(const const struct perf_evlist *evlist);
-u16 perf_evlist__id_hdr_size(const struct perf_evlist *evlist);
+u64 perf_evlist__sample_type(struct perf_evlist *evlist);
+bool perf_evlist__sample_id_all(struct perf_evlist *evlist);
+u16 perf_evlist__id_hdr_size(struct perf_evlist *evlist);
 
 int perf_evlist__parse_sample(struct perf_evlist *evlist, union perf_event *event,
 			      struct perf_sample *sample, bool swapped);
 
-bool perf_evlist__valid_sample_type(const struct perf_evlist *evlist);
-bool perf_evlist__valid_sample_id_all(const struct perf_evlist *evlist);
+bool perf_evlist__valid_sample_type(struct perf_evlist *evlist);
+bool perf_evlist__valid_sample_id_all(struct perf_evlist *evlist);
 
 void perf_evlist__splice_list_tail(struct perf_evlist *evlist,
 				   struct list_head *list,
 				   int nr_entries);
+
+static inline struct perf_evsel *perf_evlist__first(struct perf_evlist *evlist)
+{
+	return list_entry(evlist->entries.next, struct perf_evsel, node);
+}
+
+static inline struct perf_evsel *perf_evlist__last(struct perf_evlist *evlist)
+{
+	return list_entry(evlist->entries.prev, struct perf_evsel, node);
+}
 #endif /* __PERF_EVLIST_H */