PERFORCE change 133211 for review

[Andre Oppermann]

http://perforce.freebsd.org/chv.cgi?CH=133211

Change 133211 by andre at andre_flirtbox on 2008/01/14 01:55:13

	When missing segment prepend to first block instead of creating a new one
	Fix segment prepending
	Add KASSERT
	Update comments

Affected files ...

.. //depot/projects/tcp_reass/netinet/tcp_reass.c#3 edit

Differences ...

==== //depot/projects/tcp_reass/netinet/tcp_reass.c#3 (text+ko) ====

@@ -182,7 +182,7 @@
 	/* Accounting. */
 	tcpstat.tcps_rcvoopack++;
 	tcpstat.tcps_rcvoobyte += *tlenp;
-	/* NB:  m_adj(m, -i) may free mbufs at the tail of a chain. */
+	/* NB: m_adj(m, -i) may free mbufs at the tail of a chain. */
 	for (n = m; n; n = n->m_next)
 		segs++;
 	tp->t_trqlen += segs;
@@ -206,11 +206,14 @@
 		tqe = TAILQ_FIRST(&tp->t_trq);
 		KASSERT(tqe != NULL,
 		    ("%s: missing segment but nothing in queue", __func__));
+		KASSERT(SEQ_GT(tqe->trq_seq, th->th_seq),
+		    ("%s: first block already contains missing segment", __func__));
 		if (SEQ_LT(tqe->trq_seq, th->th_seq + *tlenp)) {
-			/* Trim tail. */
+			/* Trim tail of segment. */
 			if ((i = tqe->trq_seq - (th->th_seq + *tlenp))) {
 				m_adj(m, i);
 				*tlenp -= i;
+				/* tcpstat */
 				/* Update accounting. */
 				if (segs > 1) {
 					for (n = m; n; n = n->m_next)
@@ -219,18 +222,26 @@
 					tcp_reass_qsize -= segs;
 				}
 			}
+			/* Segment prepends first block. */
+			tqe->trq_len += *tlenp;
+			tqe->trq_segs += segs;
+			tqe->trq_seq = th->th_seq;
+			n = m_last(m);
+			n->m_next = tqe->trq_m;
+			tqe->trq_m = m;
+			goto present;
 		}
 		goto insert;
 	}
 
 	/* See where it fits. */
 	TAILQ_FOREACH(tqe, &tp->t_trq, trq_q) {
-		/* Segment is after our coverage. */
+		/* Segment is after this blocks coverage. */
 		if (SEQ_LT(tqe->trq_seq + tqe->trq_len, th->th_seq))
 			continue;
-		/* Segment is after the previous one but before us. */
+		/* Segment is after the previous one but before this one. */
 		if (SEQ_GT(tqe->trq_seq, th->th_seq + *tlenp))
-			break;
+			break;		/* Insert as new block. */
 		/* Segment is already fully covered. */
 		if (SEQ_LEQ(tqe->trq_seq, th->th_seq) &&
 		    SEQ_GEQ(tqe->trq_seq + tqe->trq_len, th->th_seq + *tlenp)) {
@@ -242,25 +253,28 @@
 			*tlenp = 0;
 			return (0);
 		}
-		/* Segment appends. */
+		/* Segment appends to this block. */
 		if (SEQ_LEQ(tqe->trq_seq + tqe->trq_len, th->th_seq)) {
-			/* Trim head. */
+			/* Trim head of segment. */
 			if ((i = tqe->trq_seq + tqe->trq_len - th->th_seq)) {
 				m_adj(m, i);
 				*tlenp -= i;
+				/* tcpstat */
 			}
 			tqe->trq_len += *tlenp;
 			tqe->trq_segs += segs;
 			tqe->trq_ml->m_next = m;
 			tqe->trq_ml = m_last(m);
-			/* Check for next block to merge. */
+			/* Check if segment bridges two blocks to merge. */
 			if ((tqen = TAILQ_NEXT(tqe, trq_q)) &&
 			    SEQ_GEQ(tqe->trq_seq + tqe->trq_len, tqen->trq_seq)) {
-				/* Trim head. */
+				/* Trim head of next block. */
+				/* XXXAO: Should trim tail of segment instead. */
 				if ((i = tqe->trq_seq + tqe->trq_len -
 				    tqen->trq_seq)) {
 					m_adj(tqen->trq_m, i);
 					tqen->trq_len -= i;
+					/* tcpstat */
 				}
 				tqe->trq_len += tqen->trq_len;
 				tqe->trq_segs += tqen->trq_segs;
@@ -273,7 +287,7 @@
 		}
 		/* Segment prepends. */
 		if (SEQ_GT(tqe->trq_seq, th->th_seq)) {
-			/* Trim tail. */
+			/* Trim tail of segment. */
 			if ((i = tqe->trq_seq - (th->th_seq + *tlenp))) {
 				m_adj(m, i);
 				*tlenp -= i;
@@ -287,9 +301,10 @@
 			}
 			tqe->trq_len += *tlenp;
 			tqe->trq_segs += segs;
-			tqe->trq_m = m;
+			tqe->trq_seq = th->th_seq;
 			n = m_last(m);
 			n->m_next = tqe->trq_m;
+			tqe->trq_m = m;
 			return (0);
 		}
 	}