perf callchain: Free callchains when hist entries are deleted

Markus reported that "perf top -g" can leak ~300MB per second on his
machine.  This is partly because it missed to free callchains when hist
entries are deleted.  Fix it.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20141230053813.GD6081@sejong
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/callchain.c

@@ -841,3 +841,33 @@ char *callchain_list__sym_name(struct callchain_list *cl,
 
 	return bf;
 }
+
+static void free_callchain_node(struct callchain_node *node)
+{
+	struct callchain_list *list, *tmp;
+	struct callchain_node *child;
+	struct rb_node *n;
+
+	list_for_each_entry_safe(list, tmp, &node->val, list) {
+		list_del(&list->list);
+		free(list);
+	}
+
+	n = rb_first(&node->rb_root_in);
+	while (n) {
+		child = container_of(n, struct callchain_node, rb_node_in);
+		n = rb_next(n);
+		rb_erase(&child->rb_node_in, &node->rb_root_in);
+
+		free_callchain_node(child);
+		free(child);
+	}
+}
+
+void free_callchain(struct callchain_root *root)
+{
+	if (!symbol_conf.use_callchain)
+		return;
+
+	free_callchain_node(&root->node);
+}

tools/perf/util/callchain.h

@@ -198,4 +198,6 @@ static inline int arch_skip_callchain_idx(struct thread *thread __maybe_unused,
 char *callchain_list__sym_name(struct callchain_list *cl,
 			       char *bf, size_t bfsize, bool show_dso);
 
+void free_callchain(struct callchain_root *root);
+
 #endif	/* __PERF_CALLCHAIN_H */

tools/perf/util/hist.c

@@ -947,6 +947,7 @@ void hist_entry__free(struct hist_entry *he)
 	zfree(&he->mem_info);
 	zfree(&he->stat_acc);
 	free_srcline(he->srcline);
+	free_callchain(he->callchain);
 	free(he);
 }