mirror of
https://github.com/Fishwaldo/Star64_linux.git
synced 2025-03-16 04:04:06 +00:00
libbpf: Fix race when pinning maps in parallel
[ Upstream commit 043c5bb3c4
]
When loading in parallel multiple programs which use the same to-be
pinned map, it is possible that two instances of the loader will call
bpf_object__create_maps() at the same time. If the map doesn't exist
when both instances call bpf_object__reuse_map(), then one of the
instances will fail with EEXIST when calling bpf_map__pin().
Fix the race by retrying reusing a map if bpf_map__pin() returns
EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
Fix race condition with map pinning").
Before retrying the pinning, we don't do any special cleaning of an
internal map state. The closer code inspection revealed that it's not
required:
- bpf_object__create_map(): map->inner_map is destroyed after a
successful call, map->fd is closed if pinning fails.
- bpf_object__populate_internal_map(): created map elements is
destroyed upon close(map->fd).
- init_map_slots(): slots are freed after their initialization.
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210726152001.34845-1-m@lambda.lt
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
c08b1c123f
commit
19192189e8
1 changed files with 14 additions and 1 deletions
|
@ -4656,10 +4656,13 @@ bpf_object__create_maps(struct bpf_object *obj)
|
|||
char *cp, errmsg[STRERR_BUFSIZE];
|
||||
unsigned int i, j;
|
||||
int err;
|
||||
bool retried;
|
||||
|
||||
for (i = 0; i < obj->nr_maps; i++) {
|
||||
map = &obj->maps[i];
|
||||
|
||||
retried = false;
|
||||
retry:
|
||||
if (map->pin_path) {
|
||||
err = bpf_object__reuse_map(map);
|
||||
if (err) {
|
||||
|
@ -4667,6 +4670,12 @@ bpf_object__create_maps(struct bpf_object *obj)
|
|||
map->name);
|
||||
goto err_out;
|
||||
}
|
||||
if (retried && map->fd < 0) {
|
||||
pr_warn("map '%s': cannot find pinned map\n",
|
||||
map->name);
|
||||
err = -ENOENT;
|
||||
goto err_out;
|
||||
}
|
||||
}
|
||||
|
||||
if (map->fd >= 0) {
|
||||
|
@ -4700,9 +4709,13 @@ bpf_object__create_maps(struct bpf_object *obj)
|
|||
if (map->pin_path && !map->pinned) {
|
||||
err = bpf_map__pin(map, NULL);
|
||||
if (err) {
|
||||
zclose(map->fd);
|
||||
if (!retried && err == -EEXIST) {
|
||||
retried = true;
|
||||
goto retry;
|
||||
}
|
||||
pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
|
||||
map->name, map->pin_path, err);
|
||||
zclose(map->fd);
|
||||
goto err_out;
|
||||
}
|
||||
}
|
||||
|
|
Loading…
Add table
Reference in a new issue