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Merge branch 'Fix pining maps after reuse map fd'

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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: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2020-10-06 11:10:20 -07:00
commit fd08f944e0
2 changed files with 95 additions and 36 deletions
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82
tools/lib/bpf/libbpf.c
View File

@ -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)
{
@ -4226,47 +4256,29 @@ 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;
}
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);
if (bpf_map__is_internal(map)) {
err = bpf_object__populate_internal_map(obj, map);
if (err < 0) {
zclose(map->fd);
} else {
err = bpf_object__create_map(obj, map);
if (err)
goto err_out;
}
}
if (map->init_slots_sz) {
for (j = 0; j < map->init_slots_sz; j++) {
const struct bpf_map *targ_map;
int fd;
pr_debug("map '%s': created successfully, fd=%d\n",
map->name, map->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);
if (bpf_map__is_internal(map)) {
err = bpf_object__populate_internal_map(obj, map);
if (err < 0) {
zclose(map->fd);
goto err_out;
}
}
if (map->init_slots_sz) {
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) {

49
tools/testing/selftests/bpf/prog_tests/pinning.c
View File

@ -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);