On Tue, Nov 01, 2022 at 09:34 PM -07, Cong Wang wrote:
> From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
>
> Stanislav reported a lockdep warning, which is caused by the
> cancel_work_sync() called inside sock_map_close(), as analyzed
> below by Jakub:
>
> psock->work.func = sk_psock_backlog()
> ACQUIRE psock->work_mutex
> sk_psock_handle_skb()
> skb_send_sock()
> __skb_send_sock()
> sendpage_unlocked()
> kernel_sendpage()
> sock->ops->sendpage = inet_sendpage()
> sk->sk_prot->sendpage = tcp_sendpage()
> ACQUIRE sk->sk_lock
> tcp_sendpage_locked()
> RELEASE sk->sk_lock
> RELEASE psock->work_mutex
>
> sock_map_close()
> ACQUIRE sk->sk_lock
> sk_psock_stop()
> sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED)
> cancel_work_sync()
> __cancel_work_timer()
> __flush_work()
> // wait for psock->work to finish
> RELEASE sk->sk_lock
>
> We can move the cancel_work_sync() out of the sock lock protection,
> but still before saved_close() was called.
>
> Fixes: 799aa7f98d53 ("skmsg: Avoid lock_sock() in sk_psock_backlog()")
> Reported-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> ---
[...]
Thanks!
Acked-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Tested-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
