[PATCH AUTOSEL 5.7 128/274] libbpf: Refactor map creation logic and fix cleanup leak

Sasha Levin
2020-06-09T00:56:56Z

From: Andrii Nakryiko <andriin@fb.com>

[ Upstream commit 2d39d7c56f115148b05d1d8c6b8698a5730c8b53 ]

Factor out map creation and destruction logic to simplify code and especially
error handling. Also fix map FD leak in case of partially successful map
creation during bpf_object load operation.

Fixes: 57a00f41644f ("libbpf: Add auto-pinning of maps when loading BPF objects")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200429002739.48006-3-andriin@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/libbpf.c | 226 ++++++++++++++++++++++-------------------
1 file changed, 121 insertions(+), 105 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8f480e29a6b0..63fc872723fc 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3482,107 +3482,111 @@ bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
return 0;
}

+static void bpf_map__destroy(struct bpf_map *map);
+
+static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
+{
+ struct bpf_create_map_attr create_attr;
+ struct bpf_map_def *def = &map->def;
+
+ memset(&create_attr, 0, sizeof(create_attr));
+
+ if (obj->caps.name)
+ create_attr.name = map->name;
+ create_attr.map_ifindex = map->map_ifindex;
+ create_attr.map_type = def->type;
+ create_attr.map_flags = def->map_flags;
+ create_attr.key_size = def->key_size;
+ create_attr.value_size = def->value_size;
+
+ if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !def->max_entries) {
+ int nr_cpus;
+
+ nr_cpus = libbpf_num_possible_cpus();
+ if (nr_cpus < 0) {
+ pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
+ map->name, nr_cpus);
+ return nr_cpus;
+ }
+ pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
+ create_attr.max_entries = nr_cpus;
+ } else {
+ create_attr.max_entries = def->max_entries;
+ }
+
+ if (bpf_map__is_struct_ops(map))
+ create_attr.btf_vmlinux_value_type_id =
+ map->btf_vmlinux_value_type_id;
+
+ create_attr.btf_fd = 0;
+ create_attr.btf_key_type_id = 0;
+ create_attr.btf_value_type_id = 0;
+ if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
+ create_attr.btf_fd = btf__fd(obj->btf);
+ create_attr.btf_key_type_id = map->btf_key_type_id;
+ create_attr.btf_value_type_id = map->btf_value_type_id;
+ }
+
+ map->fd = bpf_create_map_xattr(&create_attr);
+ if (map->fd < 0 && (create_attr.btf_key_type_id ||
+ create_attr.btf_value_type_id)) {
+ char *cp, errmsg[STRERR_BUFSIZE];
+ int err = -errno;
+
+ cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+ pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
+ map->name, cp, err);
+ create_attr.btf_fd = 0;
+ create_attr.btf_key_type_id = 0;
+ create_attr.btf_value_type_id = 0;
+ map->btf_key_type_id = 0;
+ map->btf_value_type_id = 0;
+ map->fd = bpf_create_map_xattr(&create_attr);
+ }
+
+ if (map->fd < 0)
+ return -errno;
+
+ return 0;
+}
+
static int
bpf_object__create_maps(struct bpf_object *obj)
{
- struct bpf_create_map_attr create_attr = {};
- int nr_cpus = 0;
- unsigned int i;
+ struct bpf_map *map;
+ char *cp, errmsg[STRERR_BUFSIZE];
+ unsigned int i, j;
int err;

for (i = 0; i < obj->nr_maps; i++) {
- struct bpf_map *map = &obj->maps[i];
- struct bpf_map_def *def = &map->def;
- char *cp, errmsg[STRERR_BUFSIZE];
- int *pfd = &map->fd;
+ map = &obj->maps[i];

if (map->pin_path) {
err = bpf_object__reuse_map(map);
if (err) {
- pr_warn("error reusing pinned map %s\n",
+ pr_warn("map '%s': error reusing pinned map\n",
map->name);
- return err;
+ goto err_out;
}
}

if (map->fd >= 0) {
- pr_debug("skip map create (preset) %s: fd=%d\n",
+ pr_debug("map '%s': skipping creation (preset fd=%d)\n",
map->name, map->fd);
continue;
}

- if (obj->caps.name)
- create_attr.name = map->name;
- create_attr.map_ifindex = map->map_ifindex;
- create_attr.map_type = def->type;
- create_attr.map_flags = def->map_flags;
- create_attr.key_size = def->key_size;
- create_attr.value_size = def->value_size;
- if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
- !def->max_entries) {
- if (!nr_cpus)
- nr_cpus = libbpf_num_possible_cpus();
- if (nr_cpus < 0) {
- pr_warn("failed to determine number of system CPUs: %d\n",
- nr_cpus);
- err = nr_cpus;
- goto err_out;
- }
- pr_debug("map '%s': setting size to %d\n",
- map->name, nr_cpus);
- create_attr.max_entries = nr_cpus;
- } else {
- create_attr.max_entries = def->max_entries;
- }
- create_attr.btf_fd = 0;
- create_attr.btf_key_type_id = 0;
- create_attr.btf_value_type_id = 0;
- if (bpf_map_type__is_map_in_map(def->type) &&
- map->inner_map_fd >= 0)
- create_attr.inner_map_fd = map->inner_map_fd;
- if (bpf_map__is_struct_ops(map))
- create_attr.btf_vmlinux_value_type_id =
- map->btf_vmlinux_value_type_id;
-
- if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
- create_attr.btf_fd = btf__fd(obj->btf);
- create_attr.btf_key_type_id = map->btf_key_type_id;
- create_attr.btf_value_type_id = map->btf_value_type_id;
- }
-
- *pfd = bpf_create_map_xattr(&create_attr);
- if (*pfd < 0 && (create_attr.btf_key_type_id ||
- create_attr.btf_value_type_id)) {
- err = -errno;
- cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
- pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
- map->name, cp, err);
- create_attr.btf_fd = 0;
- create_attr.btf_key_type_id = 0;
- create_attr.btf_value_type_id = 0;
- map->btf_key_type_id = 0;
- map->btf_value_type_id = 0;
- *pfd = bpf_create_map_xattr(&create_attr);
- }
-
- if (*pfd < 0) {
- size_t j;
+ err = bpf_object__create_map(obj, map);
+ if (err)
+ goto err_out;

- err = -errno;
-err_out:
- cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
- pr_warn("failed to create map (name: '%s'): %s(%d)\n",
- map->name, cp, err);
- pr_perm_msg(err);
- for (j = 0; j < i; j++)
- zclose(obj->maps[j].fd);
- return err;
- }
+ 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);
if (err < 0) {
- zclose(*pfd);
+ zclose(map->fd);
goto err_out;
}
}
@@ -3590,16 +3594,23 @@ bpf_object__create_maps(struct bpf_object *obj)
if (map->pin_path && !map->pinned) {
err = bpf_map__pin(map, NULL);
if (err) {
- pr_warn("failed to auto-pin map name '%s' at '%s'\n",
- map->name, map->pin_path);
- return err;
+ pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
+ map->name, map->pin_path, err);
+ zclose(map->fd);
+ goto err_out;
}
}
-
- pr_debug("created map %s: fd=%d\n", map->name, *pfd);
}

return 0;
+
+err_out:
+ cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+ pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err);
+ pr_perm_msg(err);
+ for (j = 0; j < i; j++)
+ zclose(obj->maps[j].fd);
+ return err;
}

static int
@@ -5955,6 +5966,32 @@ int bpf_object__pin(struct bpf_object *obj, const char *path)
return 0;
}

+static void bpf_map__destroy(struct bpf_map *map)
+{
+ if (map->clear_priv)
+ map->clear_priv(map, map->priv);
+ map->priv = NULL;
+ map->clear_priv = NULL;
+
+ if (map->mmaped) {
+ munmap(map->mmaped, bpf_map_mmap_sz(map));
+ map->mmaped = NULL;
+ }
+
+ if (map->st_ops) {
+ zfree(&map->st_ops->data);
+ zfree(&map->st_ops->progs);
+ zfree(&map->st_ops->kern_func_off);
+ zfree(&map->st_ops);
+ }
+
+ zfree(&map->name);
+ zfree(&map->pin_path);
+
+ if (map->fd >= 0)
+ zclose(map->fd);
+}
+
void bpf_object__close(struct bpf_object *obj)
{
size_t i;
@@ -5970,29 +6007,8 @@ void bpf_object__close(struct bpf_object *obj)
btf__free(obj->btf);
btf_ext__free(obj->btf_ext);

- for (i = 0; i < obj->nr_maps; i++) {
- struct bpf_map *map = &obj->maps[i];
-
- if (map->clear_priv)
- map->clear_priv(map, map->priv);
- map->priv = NULL;
- map->clear_priv = NULL;
-
- if (map->mmaped) {
- munmap(map->mmaped, bpf_map_mmap_sz(map));
- map->mmaped = NULL;
- }
-
- if (map->st_ops) {
- zfree(&map->st_ops->data);
- zfree(&map->st_ops->progs);
- zfree(&map->st_ops->kern_func_off);
- zfree(&map->st_ops);
- }
-
- zfree(&map->name);
- zfree(&map->pin_path);
- }
+ for (i = 0; i < obj->nr_maps; i++)
+ bpf_map__destroy(&obj->maps[i]);

zfree(&obj->kconfig);
zfree(&obj->externs);
--
2.25.1