On Tue, Dec 01, 2020 at 11:44:10PM +0900, Kuniyuki Iwashima wrote:
[ ... ]
> diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
> index fd133516ac0e..60d7c1f28809 100644
> --- a/net/core/sock_reuseport.c
> +++ b/net/core/sock_reuseport.c
> @@ -216,9 +216,11 @@ int reuseport_add_sock(struct sock *sk, struct sock
> *sk2, bool bind_inany)
> }
> EXPORT_SYMBOL(reuseport_add_sock);
>
> -void reuseport_detach_sock(struct sock *sk)
> +struct sock *reuseport_detach_sock(struct sock *sk)
> {
> struct sock_reuseport *reuse;
> + struct bpf_prog *prog;
> + struct sock *nsk = NULL;
> int i;
>
> spin_lock_bh(&reuseport_lock);
> @@ -242,8 +244,12 @@ void reuseport_detach_sock(struct sock *sk)
>
> reuse->num_socks--;
> reuse->socks[i] = reuse->socks[reuse->num_socks];
> + prog = rcu_dereference(reuse->prog);
Is it under rcu_read_lock() here?
>
> if (sk->sk_protocol == IPPROTO_TCP) {
> + if (reuse->num_socks && !prog)
> + nsk = i == reuse->num_socks ? reuse->socks[i -
> 1] : reuse->socks[i];
> +
> reuse->num_closed_socks++;
> reuse->socks[reuse->max_socks -
> reuse->num_closed_socks] = sk;
> } else {
> @@ -264,6 +270,8 @@ void reuseport_detach_sock(struct sock *sk)
> call_rcu(&reuse->rcu, reuseport_free_rcu);
> out:
> spin_unlock_bh(&reuseport_lock);
> +
> + return nsk;
> }
> EXPORT_SYMBOL(reuseport_detach_sock);
>
> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> index 1451aa9712b0..b27241ea96bd 100644
> --- a/net/ipv4/inet_connection_sock.c
> +++ b/net/ipv4/inet_connection_sock.c
> @@ -992,6 +992,36 @@ struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
> }
> EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
>
> +void inet_csk_reqsk_queue_migrate(struct sock *sk, struct sock *nsk)
> +{
> + struct request_sock_queue *old_accept_queue, *new_accept_queue;
> +
> + old_accept_queue = &inet_csk(sk)->icsk_accept_queue;
> + new_accept_queue = &inet_csk(nsk)->icsk_accept_queue;
> +
> + spin_lock(&old_accept_queue->rskq_lock);
> + spin_lock(&new_accept_queue->rskq_lock);
I am also not very thrilled on this double spin_lock.
Can this be done in (or like) inet_csk_listen_stop() instead?
> +
> + if (old_accept_queue->rskq_accept_head) {
> + if (new_accept_queue->rskq_accept_head)
> + old_accept_queue->rskq_accept_tail->dl_next =
> + new_accept_queue->rskq_accept_head;
> + else
> + new_accept_queue->rskq_accept_tail =
> old_accept_queue->rskq_accept_tail;
> +
> + new_accept_queue->rskq_accept_head =
> old_accept_queue->rskq_accept_head;
> + old_accept_queue->rskq_accept_head = NULL;
> + old_accept_queue->rskq_accept_tail = NULL;
> +
> + WRITE_ONCE(nsk->sk_ack_backlog, nsk->sk_ack_backlog +
> sk->sk_ack_backlog);
> + WRITE_ONCE(sk->sk_ack_backlog, 0);
> + }
> +
> + spin_unlock(&new_accept_queue->rskq_lock);
> + spin_unlock(&old_accept_queue->rskq_lock);
> +}
> +EXPORT_SYMBOL(inet_csk_reqsk_queue_migrate);
> +
> struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
> struct request_sock *req, bool own_req)
> {
> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> index 45fb450b4522..545538a6bfac 100644
> --- a/net/ipv4/inet_hashtables.c
> +++ b/net/ipv4/inet_hashtables.c
> @@ -681,6 +681,7 @@ void inet_unhash(struct sock *sk)
> {
> struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
> struct inet_listen_hashbucket *ilb = NULL;
> + struct sock *nsk;
> spinlock_t *lock;
>
> if (sk_unhashed(sk))
> @@ -696,8 +697,12 @@ void inet_unhash(struct sock *sk)
> if (sk_unhashed(sk))
> goto unlock;
>
> - if (rcu_access_pointer(sk->sk_reuseport_cb))
> - reuseport_detach_sock(sk);
> + if (rcu_access_pointer(sk->sk_reuseport_cb)) {
> + nsk = reuseport_detach_sock(sk);
> + if (nsk)
> + inet_csk_reqsk_queue_migrate(sk, nsk);
> + }
> +
> if (ilb) {
> inet_unhash2(hashinfo, sk);
> ilb->count--;
> --
> 2.17.2 (Apple Git-113)
>
