mptcp: split mptcp_clean_una function

mptcp_clean_una() will wake writers in case memory could be reclaimed.
When called from mptcp_sendmsg the wakeup code isn't needed.

Move the wakeup to a new helper and then use that from the mptcp worker.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/mptcp/protocol.c

@@ -853,19 +853,25 @@ static void mptcp_clean_una(struct sock *sk)
 	}
 
 out:
-	if (cleaned) {
+	if (cleaned)
 		sk_mem_reclaim_partial(sk);
+}
 
-		/* Only wake up writers if a subflow is ready */
-		if (mptcp_is_writeable(msk)) {
-			set_bit(MPTCP_SEND_SPACE, &mptcp_sk(sk)->flags);
-			smp_mb__after_atomic();
+static void mptcp_clean_una_wakeup(struct sock *sk)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
 
-			/* set SEND_SPACE before sk_stream_write_space clears
-			 * NOSPACE
-			 */
-			sk_stream_write_space(sk);
-		}
+	mptcp_clean_una(sk);
+
+	/* Only wake up writers if a subflow is ready */
+	if (mptcp_is_writeable(msk)) {
+		set_bit(MPTCP_SEND_SPACE, &msk->flags);
+		smp_mb__after_atomic();
+
+		/* set SEND_SPACE before sk_stream_write_space clears
+		 * NOSPACE
+		 */
+		sk_stream_write_space(sk);
 	}
 }
 
@@ -1769,7 +1775,7 @@ static void mptcp_worker(struct work_struct *work)
 	long timeo = 0;
 
 	lock_sock(sk);
-	mptcp_clean_una(sk);
+	mptcp_clean_una_wakeup(sk);
 	mptcp_check_data_fin_ack(sk);
 	__mptcp_flush_join_list(msk);
 	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))