[PATCH 1/1] [DCCP]: Fix default sequence window size

[Ian McDonald <ian.mcdonald@jandi.co.nz>]

Resent to apply cleanly on latest tree. Bug fix - for 2.6.18

When using the default sequence window size (100) I got the following in
my logs:
Jun 22 14:24:09 localhost kernel: [ 1492.114775] DCCP: Step 6 failed for
DATA packet, (LSWL(6279674225) <= P.seqno(6279674749) <S.SWH(6279674324)) and (P.ackno doesn't exist or LAWL(18798206530) <P.ackno(1125899906842620) <= S.AWH(18798206548), sending SYNC...
Jun 22 14:24:09 localhost kernel: [ 1492.115147] DCCP: Step 6 failed for
DATA packet, (LSWL(6279674225) <= P.seqno(6279674750) <S.SWH(6279674324)) and (P.ackno doesn't exist or LAWL(18798206530) <P.ackno(1125899906842620) <= S.AWH(18798206549), sending SYNC...

I went to alter the default sysctl and it didn't take for new sockets.
Below patch fixes this.

I think the default is too low but it is what the DCCP spec specifies.

As a side effect of this my rx speed using iperf goes from about 2.8
Mbits/sec to 3.5. This is still far too slow but it is a step in the
right direction.

Compile tested only for IPv6 but not particularly complex change.

Signed off by: Ian McDonald <ian.mcdonald@jandi.co.nz>
---
diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index 6048373..b44c455 100644
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -26,4 +26,6 @@ extern void dccp_feat_clean(struct dccp_
 extern int  dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
 extern int  dccp_feat_init(struct dccp_minisock *dmsk);
 
+extern int  dccp_feat_default_sequence_window;
+
 #endif /* _DCCP_FEAT_H */
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index c3073e7..7f56f7e 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -504,8 +504,7 @@ int dccp_v4_conn_request(struct sock *sk
 	ireq = inet_rsk(req);
 	ireq->loc_addr = daddr;
 	ireq->rmt_addr = saddr;
-	req->rcv_wnd	= 100; /* Fake, option parsing will get the
-				  right value */
+	req->rcv_wnd	= dccp_feat_default_sequence_window;
 	ireq->opt	= NULL;
 
 	/* 
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index ff42bc4..9f3d4d7 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -31,6 +31,7 @@ #include <net/xfrm.h>
 
 #include "dccp.h"
 #include "ipv6.h"
+#include "feat.h"
 
 /* Socket used for sending RSTs and ACKs */
 static struct socket *dccp_v6_ctl_socket;
@@ -707,8 +708,7 @@ static int dccp_v6_conn_request(struct s
 	ireq = inet_rsk(req);
 	ipv6_addr_copy(&ireq6->rmt_addr, &skb->nh.ipv6h->saddr);
 	ipv6_addr_copy(&ireq6->loc_addr, &skb->nh.ipv6h->daddr);
-	req->rcv_wnd	= 100; /* Fake, option parsing will get the
-				  right value */
+	req->rcv_wnd	= dccp_feat_default_sequence_window;
 	ireq6->pktopts	= NULL;
 
 	if (ipv6_opt_accepted(sk, skb) ||
diff --git a/net/dccp/options.c b/net/dccp/options.c
index c3cda1e..daf72bb 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -29,6 +29,8 @@ int dccp_feat_default_ack_ratio	      = 
 int dccp_feat_default_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
 int dccp_feat_default_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
 
+EXPORT_SYMBOL_GPL(dccp_feat_default_sequence_window);
+
 void dccp_minisock_init(struct dccp_minisock *dmsk)
 {
 	dmsk->dccpms_sequence_window = dccp_feat_default_sequence_window;