perf maps: Add reference count checking

Add reference count checking to make sure of good use of get and put.
Add and use accessors to reduce RC_CHK clutter.

The only significant issue was in tests/thread-maps-share.c where
reference counts were released in the reverse order to acquisition,
leading to a use after put. This was fixed by reversing the put order.

Committer notes:

Extracted from a larger patch removing bits that were covered by the use
of pre-existing maps__ accessors (e.g. maps__nr_maps()) and new ones
added (maps__refcnt()) to reduce RC_CHK_ACCESS(maps)-> source code
pollution.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Link: https://lore.kernel.org/lkml/20230407230405.2931830-5-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/thread-maps-share.c

@@ -46,9 +46,9 @@ static int test__thread_maps_share(struct test_suite *test __maybe_unused, int s
 	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(maps)), 4);
 
 	/* test the maps pointer is shared */
-	TEST_ASSERT_VAL("maps don't match", maps == t1->maps);
-	TEST_ASSERT_VAL("maps don't match", maps == t2->maps);
-	TEST_ASSERT_VAL("maps don't match", maps == t3->maps);
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(maps) == RC_CHK_ACCESS(t1->maps));
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(maps) == RC_CHK_ACCESS(t2->maps));
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(maps) == RC_CHK_ACCESS(t3->maps));
 
 	/*
 	 * Verify the other leader was created by previous call.
@@ -73,7 +73,7 @@ static int test__thread_maps_share(struct test_suite *test __maybe_unused, int s
 	other_maps = other->maps;
 	TEST_ASSERT_EQUAL("wrong refcnt", refcount_read(maps__refcnt(other_maps)), 2);
 
-	TEST_ASSERT_VAL("maps don't match", other_maps == other_leader->maps);
+	TEST_ASSERT_VAL("maps don't match", RC_CHK_ACCESS(other_maps) == RC_CHK_ACCESS(other_leader->maps));
 
 	/* release thread group */
 	thread__put(leader);

tools/perf/util/maps.c

@@ -13,12 +13,12 @@
 static void maps__init(struct maps *maps, struct machine *machine)
 {
 	refcount_set(maps__refcnt(maps), 1);
-	maps->entries = RB_ROOT;
 	init_rwsem(maps__lock(maps));
-	maps->machine = machine;
-	maps->last_search_by_name = NULL;
-	maps->nr_maps = 0;
-	maps->maps_by_name = NULL;
+	RC_CHK_ACCESS(maps)->entries = RB_ROOT;
+	RC_CHK_ACCESS(maps)->machine = machine;
+	RC_CHK_ACCESS(maps)->last_search_by_name = NULL;
+	RC_CHK_ACCESS(maps)->nr_maps = 0;
+	RC_CHK_ACCESS(maps)->maps_by_name = NULL;
 }
 
 static void __maps__free_maps_by_name(struct maps *maps)
@@ -29,8 +29,8 @@ static void __maps__free_maps_by_name(struct maps *maps)
 	for (unsigned int i = 0; i < maps__nr_maps(maps); i++)
 		map__put(maps__maps_by_name(maps)[i]);
 
-	zfree(&maps->maps_by_name);
-	maps->nr_maps_allocated = 0;
+	zfree(&RC_CHK_ACCESS(maps)->maps_by_name);
+	RC_CHK_ACCESS(maps)->nr_maps_allocated = 0;
 }
 
 static int __maps__insert(struct maps *maps, struct map *map)
@@ -71,7 +71,7 @@ int maps__insert(struct maps *maps, struct map *map)
 	if (err)
 		goto out;
 
-	++maps->nr_maps;
+	++RC_CHK_ACCESS(maps)->nr_maps;
 
 	if (dso && dso->kernel) {
 		struct kmap *kmap = map__kmap(map);
@@ -88,7 +88,7 @@ int maps__insert(struct maps *maps, struct map *map)
 	 * inserted map and resort.
 	 */
 	if (maps__maps_by_name(maps)) {
-		if (maps__nr_maps(maps) > maps->nr_maps_allocated) {
+		if (maps__nr_maps(maps) > RC_CHK_ACCESS(maps)->nr_maps_allocated) {
 			int nr_allocate = maps__nr_maps(maps) * 2;
 			struct map **maps_by_name = realloc(maps__maps_by_name(maps),
 							    nr_allocate * sizeof(map));
@@ -99,8 +99,8 @@ int maps__insert(struct maps *maps, struct map *map)
 				goto out;
 			}
 
-			maps->maps_by_name = maps_by_name;
-			maps->nr_maps_allocated = nr_allocate;
+			RC_CHK_ACCESS(maps)->maps_by_name = maps_by_name;
+			RC_CHK_ACCESS(maps)->nr_maps_allocated = nr_allocate;
 		}
 		maps__maps_by_name(maps)[maps__nr_maps(maps) - 1] = map__get(map);
 		__maps__sort_by_name(maps);
@@ -122,15 +122,15 @@ void maps__remove(struct maps *maps, struct map *map)
 	struct map_rb_node *rb_node;
 
 	down_write(maps__lock(maps));
-	if (maps->last_search_by_name == map)
-		maps->last_search_by_name = NULL;
+	if (RC_CHK_ACCESS(maps)->last_search_by_name == map)
+		RC_CHK_ACCESS(maps)->last_search_by_name = NULL;
 
 	rb_node = maps__find_node(maps, map);
 	assert(rb_node->map == map);
 	__maps__remove(maps, rb_node);
 	if (maps__maps_by_name(maps))
 		__maps__free_maps_by_name(maps);
-	--maps->nr_maps;
+	--RC_CHK_ACCESS(maps)->nr_maps;
 	up_write(maps__lock(maps));
 }
 
@@ -162,33 +162,38 @@ bool maps__empty(struct maps *maps)
 
 struct maps *maps__new(struct machine *machine)
 {
-	struct maps *maps = zalloc(sizeof(*maps));
+	struct maps *result;
+	RC_STRUCT(maps) *maps = zalloc(sizeof(*maps));
 
-	if (maps != NULL)
-		maps__init(maps, machine);
+	if (ADD_RC_CHK(result, maps))
+		maps__init(result, machine);
 
-	return maps;
+	return result;
 }
 
 void maps__delete(struct maps *maps)
 {
 	maps__exit(maps);
 	unwind__finish_access(maps);
-	free(maps);
+	RC_CHK_FREE(maps);
 }
 
 struct maps *maps__get(struct maps *maps)
 {
-	if (maps)
+	struct maps *result;
+
+	if (RC_CHK_GET(result, maps))
 		refcount_inc(maps__refcnt(maps));
 
-	return maps;
+	return result;
 }
 
 void maps__put(struct maps *maps)
 {
 	if (maps && refcount_dec_and_test(maps__refcnt(maps)))
 		maps__delete(maps);
+	else
+		RC_CHK_PUT(maps);
 }
 
 struct symbol *maps__find_symbol(struct maps *maps, u64 addr, struct map **mapp)

tools/perf/util/maps.h

@@ -8,6 +8,7 @@
 #include <stdbool.h>
 #include <linux/types.h>
 #include "rwsem.h"
+#include <internal/rc_check.h>
 
 struct ref_reloc_sym;
 struct machine;
@@ -32,7 +33,7 @@ struct map *maps__find(struct maps *maps, u64 addr);
 	for (map = maps__first(maps), next = map_rb_node__next(map); map; \
 	     map = next, next = map_rb_node__next(map))
 
-struct maps {
+DECLARE_RC_STRUCT(maps) {
 	struct rb_root      entries;
 	struct rw_semaphore lock;
 	struct machine	 *machine;
@@ -65,43 +66,43 @@ void maps__put(struct maps *maps);
 
 static inline struct rb_root *maps__entries(struct maps *maps)
 {
-	return &maps->entries;
+	return &RC_CHK_ACCESS(maps)->entries;
 }
 
 static inline struct machine *maps__machine(struct maps *maps)
 {
-	return maps->machine;
+	return RC_CHK_ACCESS(maps)->machine;
 }
 
 static inline struct rw_semaphore *maps__lock(struct maps *maps)
 {
-	return &maps->lock;
+	return &RC_CHK_ACCESS(maps)->lock;
 }
 
 static inline struct map **maps__maps_by_name(struct maps *maps)
 {
-	return maps->maps_by_name;
+	return RC_CHK_ACCESS(maps)->maps_by_name;
 }
 
 static inline unsigned int maps__nr_maps(const struct maps *maps)
 {
-	return maps->nr_maps;
+	return RC_CHK_ACCESS(maps)->nr_maps;
 }
 
 static inline refcount_t *maps__refcnt(struct maps *maps)
 {
-	return &maps->refcnt;
+	return &RC_CHK_ACCESS(maps)->refcnt;
 }
 
 #ifdef HAVE_LIBUNWIND_SUPPORT
 static inline void *maps__addr_space(struct maps *maps)
 {
-	return maps->addr_space;
+	return RC_CHK_ACCESS(maps)->addr_space;
 }
 
 static inline const struct unwind_libunwind_ops *maps__unwind_libunwind_ops(const struct maps *maps)
 {
-	return maps->unwind_libunwind_ops;
+	return RC_CHK_ACCESS(maps)->unwind_libunwind_ops;
 }
 #endif
 

tools/perf/util/symbol.c

@@ -2096,8 +2096,8 @@ static int map__groups__sort_by_name_from_rbtree(struct maps *maps)
 	up_read(maps__lock(maps));
 	down_write(maps__lock(maps));
 
-	maps->maps_by_name = maps_by_name;
-	maps->nr_maps_allocated = maps__nr_maps(maps);
+	RC_CHK_ACCESS(maps)->maps_by_name = maps_by_name;
+	RC_CHK_ACCESS(maps)->nr_maps_allocated = maps__nr_maps(maps);
 
 	maps__for_each_entry(maps, rb_node)
 		maps_by_name[i++] = map__get(rb_node->map);
@@ -2132,11 +2132,12 @@ struct map *maps__find_by_name(struct maps *maps, const char *name)
 
 	down_read(maps__lock(maps));
 
-	if (maps->last_search_by_name) {
-		const struct dso *dso = map__dso(maps->last_search_by_name);
+
+	if (RC_CHK_ACCESS(maps)->last_search_by_name) {
+		const struct dso *dso = map__dso(RC_CHK_ACCESS(maps)->last_search_by_name);
 
 		if (strcmp(dso->short_name, name) == 0) {
-			map = maps->last_search_by_name;
+			map = RC_CHK_ACCESS(maps)->last_search_by_name;
 			goto out_unlock;
 		}
 	}
@@ -2156,7 +2157,7 @@ struct map *maps__find_by_name(struct maps *maps, const char *name)
 		map = rb_node->map;
 		dso = map__dso(map);
 		if (strcmp(dso->short_name, name) == 0) {
-			maps->last_search_by_name = map;
+			RC_CHK_ACCESS(maps)->last_search_by_name = map;
 			goto out_unlock;
 		}
 	}

tools/perf/util/unwind-libdw.c

@@ -230,7 +230,7 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
 	struct unwind_info *ui, ui_buf = {
 		.sample		= data,
 		.thread		= thread,
-		.machine	= thread->maps->machine,
+		.machine	= RC_CHK_ACCESS(thread->maps)->machine,
 		.cb		= cb,
 		.arg		= arg,
 		.max_stack	= max_stack,

tools/perf/util/unwind-libunwind-local.c

@@ -677,7 +677,7 @@ static int _unwind__prepare_access(struct maps *maps)
 {
 	void *addr_space = unw_create_addr_space(&accessors, 0);
 
-	maps->addr_space = addr_space;
+	RC_CHK_ACCESS(maps)->addr_space = addr_space;
 	if (!addr_space) {
 		pr_err("unwind: Can't create unwind address space.\n");
 		return -ENOMEM;

tools/perf/util/unwind-libunwind.c

@@ -14,7 +14,7 @@ struct unwind_libunwind_ops __weak *arm64_unwind_libunwind_ops;
 
 static void unwind__register_ops(struct maps *maps, struct unwind_libunwind_ops *ops)
 {
-	maps->unwind_libunwind_ops = ops;
+	RC_CHK_ACCESS(maps)->unwind_libunwind_ops = ops;
 }
 
 int unwind__prepare_access(struct maps *maps, struct map *map, bool *initialized)