Commit fd08f944 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'Fix pining maps after reuse map fd' 



Hangbin Liu says:

====================
When a user reuse map fd after creating a map manually and set the
pin_path, then load the object via libbpf. bpf_object__create_maps()
will skip pinning map if map fd exist. Fix it by add moving bpf creation
to else condition and go on checking map pin_path after that.

v3:
for selftest: use CHECK() for bpf_object__open_file() and close map fd on error

v2:
a) close map fd if init map slots failed
b) add bpf selftest for this scenario
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents dca4121c 44c4aa2b

tools/lib/bpf/libbpf.c

+46 −34
Original line number Diff line number Diff line
@@ -4203,6 +4203,36 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map) 
	return 0;

}



static int init_map_slots(struct bpf_map *map)

{

	const struct bpf_map *targ_map;

	unsigned int i;

	int fd, err;



	for (i = 0; i < map->init_slots_sz; i++) {

		if (!map->init_slots[i])

			continue;



		targ_map = map->init_slots[i];

		fd = bpf_map__fd(targ_map);

		err = bpf_map_update_elem(map->fd, &i, &fd, 0);

		if (err) {

			err = -errno;

			pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",

				map->name, i, targ_map->name,

				fd, err);

			return err;

		}

		pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",

			 map->name, i, targ_map->name, fd);

	}



	zfree(&map->init_slots);

	map->init_slots_sz = 0;



	return 0;

}



static int

bpf_object__create_maps(struct bpf_object *obj)

{
@@ -4226,15 +4256,13 @@ bpf_object__create_maps(struct bpf_object *obj) 
		if (map->fd >= 0) {

			pr_debug("map '%s': skipping creation (preset fd=%d)\n",

				 map->name, map->fd);

			continue;

		}



		} else {

			err = bpf_object__create_map(obj, map);

			if (err)

				goto err_out;



		pr_debug("map '%s': created successfully, fd=%d\n", map->name,

			 map->fd);

			pr_debug("map '%s': created successfully, fd=%d\n",

				 map->name, map->fd);



			if (bpf_map__is_internal(map)) {

				err = bpf_object__populate_internal_map(obj, map);
@@ -4245,28 +4273,12 @@ bpf_object__create_maps(struct bpf_object *obj) 
			}



			if (map->init_slots_sz) {

			for (j = 0; j < map->init_slots_sz; j++) {

				const struct bpf_map *targ_map;

				int fd;



				if (!map->init_slots[j])

					continue;



				targ_map = map->init_slots[j];

				fd = bpf_map__fd(targ_map);

				err = bpf_map_update_elem(map->fd, &j, &fd, 0);

				if (err) {

					err = -errno;

					pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",

						map->name, j, targ_map->name,

						fd, err);

				err = init_map_slots(map);

				if (err < 0) {

					zclose(map->fd);

					goto err_out;

				}

				pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",

					 map->name, j, targ_map->name, fd);

			}

			zfree(&map->init_slots);

			map->init_slots_sz = 0;

		}



		if (map->pin_path && !map->pinned) {

tools/testing/selftests/bpf/prog_tests/pinning.c

+48 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ void test_pinning(void) 
	struct stat statbuf = {};

	struct bpf_object *obj;

	struct bpf_map *map;

	int err;

	int err, map_fd;

	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,

		.pin_root_path = custpath,

	);
@@ -213,6 +213,53 @@ void test_pinning(void) 
	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))

		goto out;



	/* remove the custom pin path to re-test it with reuse fd below */

	err = unlink(custpinpath);

	if (CHECK(err, "unlink custpinpath", "err %d errno %d\n", err, errno))

		goto out;



	err = rmdir(custpath);

	if (CHECK(err, "rmdir custpindir", "err %d errno %d\n", err, errno))

		goto out;



	bpf_object__close(obj);



	/* test pinning at custom path with reuse fd */

	obj = bpf_object__open_file(file, NULL);

	err = libbpf_get_error(obj);

	if (CHECK(err, "default open", "err %d errno %d\n", err, errno)) {

		obj = NULL;

		goto out;

	}



	map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(__u32),

				sizeof(__u64), 1, 0);

	if (CHECK(map_fd < 0, "create pinmap manually", "fd %d\n", map_fd))

		goto out;



	map = bpf_object__find_map_by_name(obj, "pinmap");

	if (CHECK(!map, "find map", "NULL map"))

		goto close_map_fd;



	err = bpf_map__reuse_fd(map, map_fd);

	if (CHECK(err, "reuse pinmap fd", "err %d errno %d\n", err, errno))

		goto close_map_fd;



	err = bpf_map__set_pin_path(map, custpinpath);

	if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))

		goto close_map_fd;



	err = bpf_object__load(obj);

	if (CHECK(err, "custom load", "err %d errno %d\n", err, errno))

		goto close_map_fd;



	/* check that pinmap was pinned at the custom path */

	err = stat(custpinpath, &statbuf);

	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))

		goto close_map_fd;



close_map_fd:

	close(map_fd);

out:

	unlink(pinpath);

	unlink(nopinpath);

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