Commit 4580b25f authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Alexei Starovoitov
Browse files

libbpf: Store map pin path and status in struct bpf_map 



Support storing and setting a pin path in struct bpf_map, which can be used
for automatic pinning. Also store the pin status so we can avoid attempts
to re-pin a map that has already been pinned (or reused from a previous
pinning).

The behaviour of bpf_object__{un,}pin_maps() is changed so that if it is
called with a NULL path argument (which was previously illegal), it will
(un)pin only those maps that have a pin_path set.

Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157269297876.394725.14782206533681896279.stgit@toke.dk
parent d1b4574a

tools/lib/bpf/libbpf.c

+123 −41
Original line number Diff line number Diff line
@@ -227,6 +227,8 @@ struct bpf_map { 
	void *priv;

	bpf_map_clear_priv_t clear_priv;

	enum libbpf_map_type libbpf_type;

	char *pin_path;

	bool pinned;

};



struct bpf_secdata {
@@ -4036,47 +4038,119 @@ int bpf_map__pin(struct bpf_map *map, const char *path) 
	char *cp, errmsg[STRERR_BUFSIZE];

	int err;



	err = check_path(path);

	if (err)

		return err;



	if (map == NULL) {

		pr_warn("invalid map pointer\n");

		return -EINVAL;

	}



	if (bpf_obj_pin(map->fd, path)) {

		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));

		pr_warn("failed to pin map: %s\n", cp);

		return -errno;

	if (map->pin_path) {

		if (path && strcmp(path, map->pin_path)) {

			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",

				bpf_map__name(map), map->pin_path, path);

			return -EINVAL;

		} else if (map->pinned) {

			pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",

				 bpf_map__name(map), map->pin_path);

			return 0;

		}

	} else {

		if (!path) {

			pr_warn("missing a path to pin map '%s' at\n",

				bpf_map__name(map));

			return -EINVAL;

		} else if (map->pinned) {

			pr_warn("map '%s' already pinned\n", bpf_map__name(map));

			return -EEXIST;

		}



	pr_debug("pinned map '%s'\n", path);

		map->pin_path = strdup(path);

		if (!map->pin_path) {

			err = -errno;

			goto out_err;

		}

	}



	err = check_path(map->pin_path);

	if (err)

		return err;



	if (bpf_obj_pin(map->fd, map->pin_path)) {

		err = -errno;

		goto out_err;

	}



	map->pinned = true;

	pr_debug("pinned map '%s'\n", map->pin_path);



	return 0;



out_err:

	cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));

	pr_warn("failed to pin map: %s\n", cp);

	return err;

}



int bpf_map__unpin(struct bpf_map *map, const char *path)

{

	int err;



	err = check_path(path);

	if (err)

		return err;



	if (map == NULL) {

		pr_warn("invalid map pointer\n");

		return -EINVAL;

	}



	if (map->pin_path) {

		if (path && strcmp(path, map->pin_path)) {

			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",

				bpf_map__name(map), map->pin_path, path);

			return -EINVAL;

		}

		path = map->pin_path;

	} else if (!path) {

		pr_warn("no path to unpin map '%s' from\n",

			bpf_map__name(map));

		return -EINVAL;

	}



	err = check_path(path);

	if (err)

		return err;



	err = unlink(path);

	if (err != 0)

		return -errno;

	pr_debug("unpinned map '%s'\n", path);



	map->pinned = false;

	pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);



	return 0;

}



int bpf_map__set_pin_path(struct bpf_map *map, const char *path)

{

	char *new = NULL;



	if (path) {

		new = strdup(path);

		if (!new)

			return -errno;

	}



	free(map->pin_path);

	map->pin_path = new;

	return 0;

}



const char *bpf_map__get_pin_path(const struct bpf_map *map)

{

	return map->pin_path;

}



bool bpf_map__is_pinned(const struct bpf_map *map)

{

	return map->pinned;

}



int bpf_object__pin_maps(struct bpf_object *obj, const char *path)

{

	struct bpf_map *map;
@@ -4095,7 +4169,10 @@ int bpf_object__pin_maps(struct bpf_object *obj, const char *path) 
		return err;



	bpf_object__for_each_map(map, obj) {

		char *pin_path = NULL;

		char buf[PATH_MAX];



		if (path) {

			int len;



			len = snprintf(buf, PATH_MAX, "%s/%s", path,
@@ -4107,8 +4184,12 @@ int bpf_object__pin_maps(struct bpf_object *obj, const char *path) 
				err = -ENAMETOOLONG;

				goto err_unpin_maps;

			}

			pin_path = buf;

		} else if (!map->pin_path) {

			continue;

		}



		err = bpf_map__pin(map, buf);

		err = bpf_map__pin(map, pin_path);

		if (err)

			goto err_unpin_maps;

	}
@@ -4117,17 +4198,10 @@ int bpf_object__pin_maps(struct bpf_object *obj, const char *path) 


err_unpin_maps:

	while ((map = bpf_map__prev(map, obj))) {

		char buf[PATH_MAX];

		int len;



		len = snprintf(buf, PATH_MAX, "%s/%s", path,

			       bpf_map__name(map));

		if (len < 0)

			continue;

		else if (len >= PATH_MAX)

		if (!map->pin_path)

			continue;



		bpf_map__unpin(map, buf);

		bpf_map__unpin(map, NULL);

	}



	return err;
@@ -4142,7 +4216,10 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path) 
		return -ENOENT;



	bpf_object__for_each_map(map, obj) {

		char *pin_path = NULL;

		char buf[PATH_MAX];



		if (path) {

			int len;



			len = snprintf(buf, PATH_MAX, "%s/%s", path,
@@ -4151,8 +4228,12 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path) 
				return -EINVAL;

			else if (len >= PATH_MAX)

				return -ENAMETOOLONG;

			pin_path = buf;

		} else if (!map->pin_path) {

			continue;

		}



		err = bpf_map__unpin(map, buf);

		err = bpf_map__unpin(map, pin_path);

		if (err)

			return err;

	}
@@ -4277,6 +4358,7 @@ void bpf_object__close(struct bpf_object *obj) 


	for (i = 0; i < obj->nr_maps; i++) {

		zfree(&obj->maps[i].name);

		zfree(&obj->maps[i].pin_path);

		if (obj->maps[i].clear_priv)

			obj->maps[i].clear_priv(&obj->maps[i],

						obj->maps[i].priv);

tools/lib/bpf/libbpf.h

+8 −0
Original line number Diff line number Diff line
@@ -124,6 +124,11 @@ int bpf_object__section_size(const struct bpf_object *obj, const char *name, 
			     __u32 *size);

int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,

				__u32 *off);



/* pin_maps and unpin_maps can both be called with a NULL path, in which case

 * they will use the pin_path attribute of each map (and ignore all maps that

 * don't have a pin_path set).

 */

LIBBPF_API int bpf_object__pin_maps(struct bpf_object *obj, const char *path);

LIBBPF_API int bpf_object__unpin_maps(struct bpf_object *obj,

				      const char *path);
@@ -387,6 +392,9 @@ LIBBPF_API int bpf_map__resize(struct bpf_map *map, __u32 max_entries); 
LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map);

LIBBPF_API bool bpf_map__is_internal(const struct bpf_map *map);

LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);

LIBBPF_API int bpf_map__set_pin_path(struct bpf_map *map, const char *path);

LIBBPF_API const char *bpf_map__get_pin_path(const struct bpf_map *map);

LIBBPF_API bool bpf_map__is_pinned(const struct bpf_map *map);

LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);

LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);

tools/lib/bpf/libbpf.map

+3 −0
Original line number Diff line number Diff line
@@ -193,6 +193,9 @@ LIBBPF_0.0.5 { 


LIBBPF_0.0.6 {

	global:

		bpf_map__get_pin_path;

		bpf_map__is_pinned;

		bpf_map__set_pin_path;

		bpf_object__open_file;

		bpf_object__open_mem;

		bpf_program__get_expected_attach_type;

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