bpf: no longer acquire map_idr_lock in bpf_map_inc_not_zero()

bpf_sk_storage_clone() is the only caller of bpf_map_inc_not_zero()
and is holding rcu_read_lock().

map_idr_lock does not add any protection, just remove the cost
for passive TCP flows.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Kui-Feng Lee <kuifeng@meta.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/r/20250301191315.1532629-1-edumazet@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index d799fe8f568e1f4bf00e25763733a273a60ca9ce..1340f6779811c148577536d5be6f1ba9d80eb85e 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1593,11 +1593,8 @@ struct bpf_map *__bpf_map_inc_not_zero(struct bpf_map *map, bool uref)
 
 struct bpf_map *bpf_map_inc_not_zero(struct bpf_map *map)
 {
-       spin_lock_bh(&map_idr_lock);
-       map = __bpf_map_inc_not_zero(map, false);
-       spin_unlock_bh(&map_idr_lock);
-
-       return map;
+       lockdep_assert(rcu_read_lock_held());
+       return __bpf_map_inc_not_zero(map, false);
 }
 EXPORT_SYMBOL_GPL(bpf_map_inc_not_zero);