sctp: prepare for socket backlog behavior change

sctp_inq_push() will soon be called without BH being blocked
when generic socket code flushes the socket backlog.

It is very possible SCTP can be converted to not rely on BH,
but this needs to be done by SCTP experts.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/inqueue.c

@@ -89,10 +89,12 @@ void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
 	 * Eventually, we should clean up inqueue to not rely
 	 * on the BH related data structures.
 	 */
+	local_bh_disable();
 	list_add_tail(&chunk->list, &q->in_chunk_list);
 	if (chunk->asoc)
 		chunk->asoc->stats.ipackets++;
 	q->immediate.func(&q->immediate);
+	local_bh_enable();
 }
 
 /* Peek at the next chunk on the inqeue. */