bpf, sock_map: Move cancel_work_sync() out of sock lock

mainline inclusion
from mainline-v6.1-rc5
commit 8bbabb3f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I65HYE
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8bbabb3fddcd0f858be69ed5abc9b470a239d6f2

---------------------------

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: 799aa7f9 ("skmsg: Avoid lock_sock() in sk_psock_backlog()")
Reported-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NCong Wang <cong.wang@bytedance.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Tested-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20221102043417.279409-1-xiyou.wangcong@gmail.com
(cherry picked from commit 8bbabb3f)
Signed-off-by: NLiu Jian <liujian56@huawei.com>

Conflicts:
	net/core/skmsg.c

include/linux/skmsg.h

@@ -393,7 +393,7 @@ static inline void sk_psock_report_error(struct sk_psock *psock, int err)
 }
 
 struct sk_psock *sk_psock_init(struct sock *sk, int node);
-void sk_psock_stop(struct sk_psock *psock, bool wait);
+void sk_psock_stop(struct sk_psock *psock);
 
 int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock);
 void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock);

net/core/skmsg.c

@@ -695,16 +695,13 @@ static void sk_psock_link_destroy(struct sk_psock *psock)
 	}
 }
 
-void sk_psock_stop(struct sk_psock *psock, bool wait)
+void sk_psock_stop(struct sk_psock *psock)
 {
 	spin_lock_bh(&psock->ingress_lock);
 	sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED);
 	sk_psock_cork_free(psock);
 	__sk_psock_zap_ingress(psock);
 	spin_unlock_bh(&psock->ingress_lock);
-
-	if (wait)
-		cancel_work_sync(&psock->work);
 }
 
 static void sk_psock_destroy_deferred(struct work_struct *gc)
@@ -750,7 +747,7 @@ void sk_psock_drop(struct sock *sk, struct sk_psock *psock)
 		sk_psock_stop_verdict(sk, psock);
 	write_unlock_bh(&sk->sk_callback_lock);
 
-	sk_psock_stop(psock, false);
+	sk_psock_stop(psock);
 	call_rcu(&psock->rcu, sk_psock_destroy);
 }
 EXPORT_SYMBOL_GPL(sk_psock_drop);

net/core/sock_map.c

@@ -1651,7 +1651,7 @@ void sock_map_destroy(struct sock *sk)
 	saved_destroy = psock->saved_destroy;
 	sock_map_remove_links(sk, psock);
 	rcu_read_unlock();
-	sk_psock_stop(psock, false);
+	sk_psock_stop(psock);
 	sk_psock_put(sk, psock);
 	saved_destroy(sk);
 }
@@ -1674,9 +1674,10 @@ void sock_map_close(struct sock *sk, long timeout)
 	saved_close = psock->saved_close;
 	sock_map_remove_links(sk, psock);
 	rcu_read_unlock();
-	sk_psock_stop(psock, true);
-	sk_psock_put(sk, psock);
+	sk_psock_stop(psock);
 	release_sock(sk);
+	cancel_work_sync(&psock->work);
+	sk_psock_put(sk, psock);
 	saved_close(sk, timeout);
 }