libperf: Introduce perf_evlist__purge()

Add a static perf_evlist__purge() function to purge evsels from a evlist.

Add also perf_evlist__for_each_entry_safe() which is used by
perf_evlist__purge().

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-26-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/lib/evlist.c

@@ -109,6 +109,18 @@ perf_evlist__next(struct perf_evlist *evlist, struct perf_evsel *prev)
 	return next;
 }
 
+static void perf_evlist__purge(struct perf_evlist *evlist)
+{
+	struct perf_evsel *pos, *n;
+
+	perf_evlist__for_each_entry_safe(evlist, n, pos) {
+		list_del_init(&pos->node);
+		perf_evsel__delete(pos);
+	}
+
+	evlist->nr_entries = 0;
+}
+
 void perf_evlist__exit(struct perf_evlist *evlist)
 {
 	perf_cpu_map__put(evlist->cpus);
@@ -125,6 +137,7 @@ void perf_evlist__delete(struct perf_evlist *evlist)
 
 	perf_evlist__munmap(evlist);
 	perf_evlist__close(evlist);
+	perf_evlist__purge(evlist);
 	perf_evlist__exit(evlist);
 	free(evlist);
 }

tools/perf/lib/include/internal/evlist.h

@@ -82,6 +82,24 @@ void perf_evlist__exit(struct perf_evlist *evlist);
 #define perf_evlist__for_each_entry_reverse(evlist, evsel) \
 	__perf_evlist__for_each_entry_reverse(&(evlist)->entries, evsel)
 
+/**
+ * __perf_evlist__for_each_entry_safe - safely iterate thru all the evsels
+ * @list: list_head instance to iterate
+ * @tmp: struct evsel temp iterator
+ * @evsel: struct evsel iterator
+ */
+#define __perf_evlist__for_each_entry_safe(list, tmp, evsel) \
+	list_for_each_entry_safe(evsel, tmp, list, node)
+
+/**
+ * perf_evlist__for_each_entry_safe - safely iterate thru all the evsels
+ * @evlist: evlist instance to iterate
+ * @evsel: struct evsel iterator
+ * @tmp: struct evsel temp iterator
+ */
+#define perf_evlist__for_each_entry_safe(evlist, tmp, evsel) \
+	__perf_evlist__for_each_entry_safe(&(evlist)->entries, tmp, evsel)
+
 static inline struct perf_evsel *perf_evlist__first(struct perf_evlist *evlist)
 {
 	return list_entry(evlist->entries.next, struct perf_evsel, node);