sctp: do not return the transmit err back to sctp_sendmsg

commit 66388f2c upstream.

Once a chunk is enqueued successfully, sctp queues can take care of it.
Even if it is failed to transmit (like because of nomem), it should be
put into retransmit queue.

If sctp report this error to users, it confuses them, they may resend
that msg, but actually in kernel sctp stack is in charge of retransmit
it already.

Besides, this error probably is not from the failure of transmitting
current msg, but transmitting or retransmitting another msg's chunks,
as sctp_outq_flush just tries to send out all transports' chunks.

This patch is to make sctp_cmd_send_msg return avoid, and not return the
transmit err back to sctp_sendmsg

Fixes: 8b570dc9 ("sctp: only drop the reference on the datamsg after sending a msg")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: no gfp flags parameter]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/sctp/sm_sideeffect.c

@@ -1028,19 +1028,13 @@ static void sctp_cmd_t1_timer_update(struct sctp_association *asoc,
  * This way the whole message is queued up and bundling if
  * encouraged for small fragments.
  */
-static int sctp_cmd_send_msg(struct sctp_association *asoc,
-				struct sctp_datamsg *msg)
+static void sctp_cmd_send_msg(struct sctp_association *asoc,
+			      struct sctp_datamsg *msg)
 {
 	struct sctp_chunk *chunk;
-	int error = 0;
-
-	list_for_each_entry(chunk, &msg->chunks, frag_list) {
-		error = sctp_outq_tail(&asoc->outqueue, chunk);
-		if (error)
-			break;
-	}
 
-	return error;
+	list_for_each_entry(chunk, &msg->chunks, frag_list)
+		sctp_outq_tail(&asoc->outqueue, chunk);
 }
 
 
@@ -1714,7 +1708,7 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 				sctp_outq_cork(&asoc->outqueue);
 				local_cork = 1;
 			}
-			error = sctp_cmd_send_msg(asoc, cmd->obj.msg);
+			sctp_cmd_send_msg(asoc, cmd->obj.msg);
 			break;
 		case SCTP_CMD_SEND_NEXT_ASCONF:
 			sctp_cmd_send_asconf(asoc);