perf tools: Add refcnt into struct mem_info

It's passed along several hists entries in --hierarchy mode, so it's
better we keep track of it.

The current fail I see is that it gets removed in hierarchy --mem-mode
mode, where it's shared in the different hierarchies, but removed from
the template hist entry, so the report crashes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180307155020.32613-6-jolsa@kernel.org
[ Rename mem_info__aloc() to mem_info__new(), to fix the typo and use the convention for constructors ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/hist.c

@@ -536,7 +536,7 @@ static struct hist_entry *hists__findnew_entry(struct hists *hists,
 			 * This mem info was allocated from sample__resolve_mem
 			 * and will not be used anymore.
 			 */
-			zfree(&entry->mem_info);
+			mem_info__zput(entry->mem_info);
 
 			/* If the map of an existing hist_entry has
 			 * become out-of-date due to an exec() or
@@ -1139,7 +1139,7 @@ void hist_entry__delete(struct hist_entry *he)
 	if (he->mem_info) {
 		map__zput(he->mem_info->iaddr.map);
 		map__zput(he->mem_info->daddr.map);
-		zfree(&he->mem_info);
+		mem_info__zput(he->mem_info);
 	}
 
 	zfree(&he->stat_acc);

tools/perf/util/machine.c

@@ -1697,7 +1697,7 @@ static void ip__resolve_data(struct thread *thread,
 struct mem_info *sample__resolve_mem(struct perf_sample *sample,
 				     struct addr_location *al)
 {
-	struct mem_info *mi = zalloc(sizeof(*mi));
+	struct mem_info *mi = mem_info__new();
 
 	if (!mi)
 		return NULL;

tools/perf/util/symbol.c

@@ -2221,3 +2221,25 @@ int symbol__config_symfs(const struct option *opt __maybe_unused,
 	free(bf);
 	return 0;
 }
+
+struct mem_info *mem_info__get(struct mem_info *mi)
+{
+	if (mi)
+		refcount_inc(&mi->refcnt);
+	return mi;
+}
+
+void mem_info__put(struct mem_info *mi)
+{
+	if (mi && refcount_dec_and_test(&mi->refcnt))
+		free(mi);
+}
+
+struct mem_info *mem_info__new(void)
+{
+	struct mem_info *mi = zalloc(sizeof(*mi));
+
+	if (mi)
+		refcount_set(&mi->refcnt, 1);
+	return mi;
+}

tools/perf/util/symbol.h

@@ -203,6 +203,7 @@ struct mem_info {
 	struct addr_map_symbol	iaddr;
 	struct addr_map_symbol	daddr;
 	union perf_mem_data_src	data_src;
+	refcount_t		refcnt;
 };
 
 struct addr_location {
@@ -389,4 +390,16 @@ int sdt_notes__get_count(struct list_head *start);
 #define SDT_NOTE_NAME "stapsdt"
 #define NR_ADDR 3
 
+struct mem_info *mem_info__new(void);
+struct mem_info *mem_info__get(struct mem_info *mi);
+void   mem_info__put(struct mem_info *mi);
+
+static inline void __mem_info__zput(struct mem_info **mi)
+{
+	mem_info__put(*mi);
+	*mi = NULL;
+}
+
+#define mem_info__zput(mi) __mem_info__zput(&mi)
+
 #endif /* __PERF_SYMBOL */