[PATCH v4 bpf-next 2/7] libbpf: cleanup after partial failure in bpf_object__pin

From: Stanislav Fomichev sdf@google.com

bpftool will use bpf_object__pin in the next commits to pin all programs and maps from the file; in case of a partial failure, we need to get back to the clean state (undo previous program/map pins).

As part of a cleanup, I've added and exported separate routines to pin all maps (bpf_object__pin_maps) and progs (bpf_object__pin_programs) of an object.

Signed-off-by: Stanislav Fomichev sdf@google.com --- tools/lib/bpf/libbpf.c | 328 ++++++++++++++++++++++++++++++++++++++--- tools/lib/bpf/libbpf.h | 18 +++ 2 files changed, 323 insertions(+), 23 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index d6e62e90e8d4..f8590490a9dd 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1699,6 +1699,34 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path, return 0; }

+int bpf_program__unpin_instance(struct bpf_program *prog, const char *path, + int instance) +{ + int err; + + err = check_path(path); + if (err) + return err; + + if (prog == NULL) { + pr_warning("invalid program pointer\n"); + return -EINVAL; + } + + if (instance < 0 || instance >= prog->instances.nr) { + pr_warning("invalid prog instance %d of prog %s (max %d)\n", + instance, prog->section_name, prog->instances.nr); + return -EINVAL; + } + + err = unlink(path); + if (err != 0) + return -errno; + pr_debug("unpinned program '%s'\n", path); + + return 0; +} + static int make_dir(const char *path) { char *cp, errmsg[STRERR_BUFSIZE]; @@ -1737,6 +1765,64 @@ int bpf_program__pin(struct bpf_program *prog, const char *path) if (err) return err;

+ for (i = 0; i < prog->instances.nr; i++) { + char buf[PATH_MAX]; + int len; + + len = snprintf(buf, PATH_MAX, "%s/%d", path, i); + if (len < 0) { + err = -EINVAL; + goto err_unpin; + } else if (len >= PATH_MAX) { + err = -ENAMETOOLONG; + goto err_unpin; + } + + err = bpf_program__pin_instance(prog, buf, i); + if (err) + goto err_unpin; + } + + return 0; + +err_unpin: + for (i = i - 1; i >= 0; i--) { + char buf[PATH_MAX]; + int len; + + len = snprintf(buf, PATH_MAX, "%s/%d", path, i); + if (len < 0) + continue; + else if (len >= PATH_MAX) + continue; + + bpf_program__unpin_instance(prog, buf, i); + } + + rmdir(path); + + return err; +} + +int bpf_program__unpin(struct bpf_program *prog, const char *path) +{ + int i, err; + + err = check_path(path); + if (err) + return err; + + if (prog == NULL) { + pr_warning("invalid program pointer\n"); + return -EINVAL; + } + + if (prog->instances.nr <= 0) { + pr_warning("no instances of prog %s to pin\n", + prog->section_name); + return -EINVAL; + } + for (i = 0; i < prog->instances.nr; i++) { char buf[PATH_MAX]; int len; @@ -1747,11 +1833,15 @@ int bpf_program__pin(struct bpf_program *prog, const char *path) else if (len >= PATH_MAX) return -ENAMETOOLONG;

- err = bpf_program__pin_instance(prog, buf, i); + err = bpf_program__unpin_instance(prog, buf, i); if (err) return err; }

+ err = rmdir(path); + if (err) + return -errno; + return 0; }

@@ -1776,12 +1866,33 @@ int bpf_map__pin(struct bpf_map *map, const char *path) }

pr_debug("pinned map '%s'\n", path); + return 0; }

-int bpf_object__pin(struct bpf_object *obj, const char *path) +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_warning("invalid map pointer\n"); + return -EINVAL; + } + + err = unlink(path); + if (err != 0) + return -errno; + pr_debug("unpinned map '%s'\n", path); + + return 0; +} + +int bpf_object__pin_maps(struct bpf_object *obj, const char *path) { - struct bpf_program *prog; struct bpf_map *map; int err;

@@ -1797,6 +1908,55 @@ int bpf_object__pin(struct bpf_object *obj, const char *path) if (err) return err;

+ bpf_map__for_each(map, obj) { + char buf[PATH_MAX]; + int len; + + len = snprintf(buf, PATH_MAX, "%s/%s", path, + bpf_map__name(map)); + if (len < 0) { + err = -EINVAL; + goto err_unpin_maps; + } else if (len >= PATH_MAX) { + err = -ENAMETOOLONG; + goto err_unpin_maps; + } + + err = bpf_map__pin(map, buf); + if (err) + goto err_unpin_maps; + } + + return 0; + +err_unpin_maps: + for (map = bpf_map__prev(map, obj); + map != NULL; + 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) + continue; + + bpf_map__unpin(map, buf); + } + + return err; +} + +int bpf_object__unpin_maps(struct bpf_object *obj, const char *path) +{ + struct bpf_map *map; + int err; + + if (!obj) + return -ENOENT; + bpf_map__for_each(map, obj) { char buf[PATH_MAX]; int len; @@ -1808,11 +1968,80 @@ int bpf_object__pin(struct bpf_object *obj, const char *path) else if (len >= PATH_MAX) return -ENAMETOOLONG;

- err = bpf_map__pin(map, buf); + err = bpf_map__unpin(map, buf); if (err) return err; }

+ return 0; +} + +int bpf_object__pin_programs(struct bpf_object *obj, const char *path) +{ + struct bpf_program *prog; + int err; + + if (!obj) + return -ENOENT; + + if (!obj->loaded) { + pr_warning("object not yet loaded; load it first\n"); + return -ENOENT; + } + + err = make_dir(path); + if (err) + return err; + + bpf_object__for_each_program(prog, obj) { + char buf[PATH_MAX]; + int len; + + len = snprintf(buf, PATH_MAX, "%s/%s", path, + prog->section_name); + if (len < 0) { + err = -EINVAL; + goto err_unpin_programs; + } else if (len >= PATH_MAX) { + err = -ENAMETOOLONG; + goto err_unpin_programs; + } + + err = bpf_program__pin(prog, buf); + if (err) + goto err_unpin_programs; + } + + return 0; + +err_unpin_programs: + for (prog = bpf_program__prev(prog, obj); + prog != NULL; + prog = bpf_program__prev(prog, obj)) { + char buf[PATH_MAX]; + int len; + + len = snprintf(buf, PATH_MAX, "%s/%s", path, + prog->section_name); + if (len < 0) + continue; + else if (len >= PATH_MAX) + continue; + + bpf_program__unpin(prog, buf); + } + + return err; +} + +int bpf_object__unpin_programs(struct bpf_object *obj, const char *path) +{ + struct bpf_program *prog; + int err; + + if (!obj) + return -ENOENT; + bpf_object__for_each_program(prog, obj) { char buf[PATH_MAX]; int len; @@ -1824,7 +2053,7 @@ int bpf_object__pin(struct bpf_object *obj, const char *path) else if (len >= PATH_MAX) return -ENAMETOOLONG;

- err = bpf_program__pin(prog, buf); + err = bpf_program__unpin(prog, buf); if (err) return err; } @@ -1832,6 +2061,23 @@ int bpf_object__pin(struct bpf_object *obj, const char *path) return 0; }

+int bpf_object__pin(struct bpf_object *obj, const char *path) +{ + int err; + + err = bpf_object__pin_maps(obj, path); + if (err) + return err; + + err = bpf_object__pin_programs(obj, path); + if (err) { + bpf_object__unpin_maps(obj, path); + return err; + } + + return 0; +} + void bpf_object__close(struct bpf_object *obj) { size_t i; @@ -1918,23 +2164,20 @@ void *bpf_object__priv(struct bpf_object *obj) }

static struct bpf_program * -__bpf_program__next(struct bpf_program *prev, struct bpf_object *obj) +__bpf_program__iter(struct bpf_program *p, struct bpf_object *obj, int i) { - size_t idx; + ssize_t idx;

if (!obj->programs) return NULL; - /* First handler */ - if (prev == NULL) - return &obj->programs[0];

- if (prev->obj != obj) { + if (p->obj != obj) { pr_warning("error: program handler doesn't match object\n"); return NULL; }

- idx = (prev - obj->programs) + 1; - if (idx >= obj->nr_programs) + idx = (p - obj->programs) + i; + if (idx >= obj->nr_programs || idx < 0) return NULL; return &obj->programs[idx]; } @@ -1944,8 +2187,29 @@ bpf_program__next(struct bpf_program *prev, struct bpf_object *obj) { struct bpf_program *prog = prev;

+ if (prev == NULL) + return obj->programs; + do { - prog = __bpf_program__next(prog, obj); + prog = __bpf_program__iter(prog, obj, 1); + } while (prog && bpf_program__is_function_storage(prog, obj)); + + return prog; +} + +struct bpf_program * +bpf_program__prev(struct bpf_program *next, struct bpf_object *obj) +{ + struct bpf_program *prog = next; + + if (next == NULL) { + if (!obj->nr_programs) + return NULL; + return obj->programs + obj->nr_programs - 1; + } + + do { + prog = __bpf_program__iter(prog, obj, -1); } while (prog && bpf_program__is_function_storage(prog, obj));

return prog; @@ -2272,10 +2536,10 @@ void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex) map->map_ifindex = ifindex; }

-struct bpf_map * -bpf_map__next(struct bpf_map *prev, struct bpf_object *obj) +static struct bpf_map * +__bpf_map__iter(struct bpf_map *m, struct bpf_object *obj, int i) { - size_t idx; + ssize_t idx; struct bpf_map *s, *e;

if (!obj || !obj->maps) @@ -2284,21 +2548,39 @@ bpf_map__next(struct bpf_map *prev, struct bpf_object *obj) s = obj->maps; e = obj->maps + obj->nr_maps;

- if (prev == NULL) - return s; - - if ((prev < s) || (prev >= e)) { + if ((m < s) || (m >= e)) { pr_warning("error in %s: map handler doesn't belong to object\n", __func__); return NULL; }

- idx = (prev - obj->maps) + 1; - if (idx >= obj->nr_maps) + idx = (m - obj->maps) + i; + if (idx >= obj->nr_maps || idx < 0) return NULL; return &obj->maps[idx]; }

+struct bpf_map * +bpf_map__next(struct bpf_map *prev, struct bpf_object *obj) +{ + if (prev == NULL) + return obj->maps; + + return __bpf_map__iter(prev, obj, 1); +} + +struct bpf_map * +bpf_map__prev(struct bpf_map *next, struct bpf_object *obj) +{ + if (next == NULL) { + if (!obj->nr_maps) + return NULL; + return obj->maps + obj->nr_maps - 1; + } + + return __bpf_map__iter(next, obj, -1); +} + struct bpf_map * bpf_object__find_map_by_name(struct bpf_object *obj, const char *name) { diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 1f3468dad8b2..b1686a787102 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -71,6 +71,13 @@ struct bpf_object *__bpf_object__open_xattr(struct bpf_object_open_attr *attr, LIBBPF_API struct bpf_object *bpf_object__open_buffer(void *obj_buf, size_t obj_buf_sz, const char *name); +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); +LIBBPF_API int bpf_object__pin_programs(struct bpf_object *obj, + const char *path); +LIBBPF_API int bpf_object__unpin_programs(struct bpf_object *obj, + const char *path); LIBBPF_API int bpf_object__pin(struct bpf_object *object, const char *path); LIBBPF_API void bpf_object__close(struct bpf_object *object);

@@ -112,6 +119,9 @@ LIBBPF_API struct bpf_program *bpf_program__next(struct bpf_program *prog, (pos) != NULL; \ (pos) = bpf_program__next((pos), (obj)))

+LIBBPF_API struct bpf_program *bpf_program__prev(struct bpf_program *prog, + struct bpf_object *obj); + typedef void (*bpf_program_clear_priv_t)(struct bpf_program *, void *);

@@ -131,7 +141,11 @@ LIBBPF_API int bpf_program__fd(struct bpf_program *prog); LIBBPF_API int bpf_program__pin_instance(struct bpf_program *prog, const char *path, int instance); +LIBBPF_API int bpf_program__unpin_instance(struct bpf_program *prog, + const char *path, + int instance); LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path); +LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path); LIBBPF_API void bpf_program__unload(struct bpf_program *prog);

struct bpf_insn; @@ -260,6 +274,9 @@ bpf_map__next(struct bpf_map *map, struct bpf_object *obj); (pos) != NULL; \ (pos) = bpf_map__next((pos), (obj)))

+LIBBPF_API struct bpf_map * +bpf_map__prev(struct bpf_map *map, struct bpf_object *obj); + LIBBPF_API int bpf_map__fd(struct bpf_map *map); LIBBPF_API const struct bpf_map_def *bpf_map__def(struct bpf_map *map); LIBBPF_API const char *bpf_map__name(struct bpf_map *map); @@ -274,6 +291,7 @@ LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd); LIBBPF_API bool bpf_map__is_offload_neutral(struct bpf_map *map); LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex); 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);

LIBBPF_API long libbpf_get_error(const void *ptr);