On Sat, Feb 6, 2021 at 9:06 AM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> ---
Great.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> kernel/bpf/hashtab.c | 4 ++--
> kernel/bpf/verifier.c | 7 ++++++-
> 2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> index c1ac7f964bc9..d63912e73ad9 100644
> --- a/kernel/bpf/hashtab.c
> +++ b/kernel/bpf/hashtab.c
> @@ -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;
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 4189edb41b73..9561f2af7710 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -10020,9 +10020,14 @@ 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;
> --
> 2.24.1
>
