[PATCH V2 08/14] perf tools: Make perf_evlist__set_maps() more resilient

[Adrian Hunter <adrian.hunter@intel.com>]

Make perf_evlist__set_maps() more resilient by allowing for the
possibility that one or another of the maps isn't being changed
and therefore should not be "put".

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 tools/perf/util/evlist.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 6764e0eff849..606fc6e63ec0 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1156,11 +1156,22 @@ int perf_evlist__set_maps(struct perf_evlist *evlist,
 			  struct cpu_map *cpus,
 			  struct thread_map *threads)
 {
-	cpu_map__put(evlist->cpus);
-	evlist->cpus = cpus;
+	/*
+	 * Allow for the possibility that one or another of the maps isn't being
+	 * changed i.e. don't put it.  Note we are assuming the maps that are
+	 * being applied are brand new and evlist is taking ownership of the
+	 * original reference count of 1.  If that is not the case it is up to
+	 * the caller to increase the reference count.
+	 */
+	if (cpus != evlist->cpus) {
+		cpu_map__put(evlist->cpus);
+		evlist->cpus = cpus;
+	}
 
-	thread_map__put(evlist->threads);
-	evlist->threads = threads;
+	if (threads != evlist->threads) {
+		thread_map__put(evlist->threads);
+		evlist->threads = threads;
+	}
 
 	perf_evlist__propagate_maps(evlist);
 
-- 
1.9.1