mptcp: remove unneeded mptcp_move_skb()

JIRA: https://issues.redhat.com/browse/RHEL-115576
Upstream Status: net-next.git commit c4ebc4e

commit c4ebc4e
Author: Paolo Abeni <pabeni@redhat.com>
Date:   Sat Sep 27 11:40:41 2025 +0200

    mptcp: remove unneeded mptcp_move_skb()

    Since commit b7535cf ("mptcp: drop legacy code around RX EOF"),
    sk_shutdown can't change during the main recvmsg loop, we can drop
    the related race breaker.

    Reviewed-by: Geliang Tang <geliang@kernel.org>
    Tested-by: Geliang Tang <geliang@kernel.org>
    Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>
    Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
    Link: https://patch.msgid.link/20250927-net-next-mptcp-rcv-path-imp-v1-5-5da266aa9c1a@kernel.org
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Davide Caratti <dcaratti@redhat.com>

Author: dcaratti

net/mptcp/protocol.c

@@ -2167,14 +2167,8 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 				break;
 			}
 
-			if (sk->sk_shutdown & RCV_SHUTDOWN) {
-				/* race breaker: the shutdown could be after the
-				 * previous receive queue check
-				 */
-				if (__mptcp_move_skbs(sk))
-					continue;
+			if (sk->sk_shutdown & RCV_SHUTDOWN)
 				break;
-			}
 
 			if (sk->sk_state == TCP_CLOSE) {
 				copied = -ENOTCONN;