sctp: remove the unnecessary state check in sctp_outq_tail

Data Chunks are only sent by sctp_primitive_SEND, in which sctp checks
the asoc's state through statetable before calling sctp_outq_tail. So
there's no need to check the asoc's state again in sctp_outq_tail.

Besides, sctp_do_sm is protected by lock_sock, even if sending msg is
interrupted by timer events, the event's processes still need to acquire
lock_sock first. It means no others CMDs can be enqueue into side effect
list before CMD_SEND_MSG to change asoc->state, so it's safe to remove it.

This patch is to remove redundant asoc->state check from sctp_outq_tail.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/outqueue.c

@@ -299,26 +299,6 @@ int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
 	 * immediately.
 	 */
 	if (sctp_chunk_is_data(chunk)) {
-		/* Is it OK to queue data chunks?  */
-		/* From 9. Termination of Association
-		 *
-		 * When either endpoint performs a shutdown, the
-		 * association on each peer will stop accepting new
-		 * data from its user and only deliver data in queue
-		 * at the time of sending or receiving the SHUTDOWN
-		 * chunk.
-		 */
-		switch (q->asoc->state) {
-		case SCTP_STATE_CLOSED:
-		case SCTP_STATE_SHUTDOWN_PENDING:
-		case SCTP_STATE_SHUTDOWN_SENT:
-		case SCTP_STATE_SHUTDOWN_RECEIVED:
-		case SCTP_STATE_SHUTDOWN_ACK_SENT:
-			/* Cannot send after transport endpoint shutdown */
-			error = -ESHUTDOWN;
-			break;
-
-		default:
 		pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
 			 __func__, q, chunk, chunk && chunk->chunk_hdr ?
 			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
@@ -333,16 +313,11 @@ int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
 			SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
 		else
 			SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
-			break;
-		}
 	} else {
 		list_add_tail(&chunk->list, &q->control_chunk_list);
 		SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 	}
 
-	if (error < 0)
-		return error;
-
 	if (!q->cork)
 		error = sctp_outq_flush(q, 0, gfp);