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bpf: Allows per-cpu maps and map-in-map in sleepable programs 

Since sleepable programs are now executing under migrate_disable
the per-cpu maps are safe to use.
The map-in-map were ok to use in sleepable from the time sleepable
progs were introduced.

Note that non-preallocated maps are still not safe, since there is
no rcu_read_lock yet in sleepable programs and dynamically allocated
map elements are relying on rcu protection. The sleepable programs
have rcu_read_lock_trace instead. That limitation will be addresses
in the future.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-9-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2021-02-09 19:36:33 -08:00 committed by Daniel Borkmann
parent dcf33b6f4d
commit 638e4b825d
2 changed files with 8 additions and 3 deletions
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4
kernel/bpf/hashtab.c
View File

@ -1148,7 +1148,7 @@ static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
/* unknown flags */
return -EINVAL;
WARN_ON_ONCE(!rcu_read_lock_held());
WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());
key_size = map->key_size;
@ -1202,7 +1202,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
/* unknown flags */
return -EINVAL;
WARN_ON_ONCE(!rcu_read_lock_held());
WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());
key_size = map->key_size;

7
kernel/bpf/verifier.c
View File

@ -10384,9 +10384,14 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env,
case BPF_MAP_TYPE_HASH:
case BPF_MAP_TYPE_LRU_HASH:
case BPF_MAP_TYPE_ARRAY:
case BPF_MAP_TYPE_PERCPU_HASH:
case BPF_MAP_TYPE_PERCPU_ARRAY:
case BPF_MAP_TYPE_LRU_PERCPU_HASH:
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
if (!is_preallocated_map(map)) {
verbose(env,
"Sleepable programs can only use preallocated hash maps\n");
"Sleepable programs can only use preallocated maps\n");
return -EINVAL;
}
break;