af_unix: Defer sock_put() to clean up path in unix_dgram_sendmsg().

When other has SOCK_DEAD in unix_dgram_sendmsg(), we call sock_put() for
it first and then set NULL to other before jumping to the error path.

This is to skip sock_put() in the error path.

Let's not set NULL to other and defer the sock_put() to the error path
to clean up the labels later.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/unix/af_unix.c

@@ -2075,7 +2075,6 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 		 *	datagram error
 		 */
 		unix_state_unlock(other);
-		sock_put(other);
 
 		if (!sk_locked)
 			unix_state_lock(sk);
@@ -2104,7 +2103,6 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 				err = -ECONNRESET;
 		}
 
-		other = NULL;
 		if (err)
 			goto out_free;