[CCID2]: Remove ugly BUG_ON

This removes an ugly BUG_ON which has been pointed out by Arnaldo.

Instead of freezing up the machine, a `critical' message is now issued
to the system log.

There is potential of doing this more gracefully (eg. there are a few
internal variables which could be updated despite the lack of memory),
but that requires more complicated changes to the algorithm; thus a
`FIXME' has been added.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dccp/ccids/ccid2.c

@@ -294,12 +294,11 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
 	next = hctx->ccid2hctx_seqh->ccid2s_next;
 	/* check if we need to alloc more space */
 	if (next == hctx->ccid2hctx_seqt) {
-		int rc;
-
-		ccid2_pr_debug("allocating more space in history\n");
-		rc = ccid2_hc_tx_alloc_seq(hctx);
-		BUG_ON(rc); /* XXX what do we do? */
-
+		if (ccid2_hc_tx_alloc_seq(hctx)) {
+			DCCP_CRIT("packet history - out of memory!");
+			/* FIXME: find a more graceful way to bail out */
+			return;
+		}
 		next = hctx->ccid2hctx_seqh->ccid2s_next;
 		BUG_ON(next == hctx->ccid2hctx_seqt);
 	}