From: Jan Glauber <jglauber@redhat.com>
Date: Tue, 25 Mar 2008 13:33:56 +0100
Subject: [s390] fix qeth scatter-gather
Message-id: 1206448436.8004.16.camel@localhost.localdomain
O-Subject: [RHEL5 U2 PATCH] s390: fix qeth scatter-gather
Bugzilla: 438180

Description
============

Test found two issues with the qeth scatter gather support that is new
with 5.2.

qeth: inbound scatter gather - fix skb page increment

If the first qdio buffer element is to short to use a page we copy
the data. In this case we are not allowed to increment the fragment
count.

qeth: Receive (RX-SG) on HiperSockets creates invalid IP packets

Invaild IP packets are created, when receive-scatter/gather (RX-SG)
is utilized in qeth. Typically the IP header is dropped.
When receiving on HiperSocket and the first SBALE buffer is
filled with data chunk smaller than 64 bytes, these data bytes
are dropped.

Bugzilla
=========
BZ: 438180

Upstream status of the patch:
=============================
Upstream 2.6.25 will have a rewritten qeth driver which is not yet in
Linus' tree.

Test status:
============
Kernel with patch was built and successfully tested.

Please ack,
Jan

jglauber@redhat.com
jang@de.ibm.com

Acked-by: Andy Gospodarek <gospo@redhat.com>

diff --git a/drivers/s390/net/qeth_main.c b/drivers/s390/net/qeth_main.c
index fa63e60..e6b9411 100644
--- a/drivers/s390/net/qeth_main.c
+++ b/drivers/s390/net/qeth_main.c
@@ -2202,7 +2202,7 @@ qeth_create_skb_frag(struct qdio_buffer_element *element,
 		     int offset, int *pfrag, int data_len)
 {
 	struct page *page = virt_to_page(element->addr);
-	if (*pfrag == 0) {
+	if (*pskb == NULL) {
 		/* the upper protocol layers assume that there is data in the
 		 * skb itself. Copy a small amount (64 bytes) to make them
 		 * happy. */
@@ -2221,6 +2221,7 @@ qeth_create_skb_frag(struct qdio_buffer_element *element,
 			(*pskb)->data_len += data_len - 64;
 			(*pskb)->len      += data_len - 64;
 			(*pskb)->truesize += data_len - 64;
+			(*pfrag)++;
 		}
 	} else {
 		get_page(page);
@@ -2228,8 +2229,8 @@ qeth_create_skb_frag(struct qdio_buffer_element *element,
 		(*pskb)->data_len += data_len;
 		(*pskb)->len      += data_len;
 		(*pskb)->truesize += data_len;
+		(*pfrag)++;
 	}
-	(*pfrag)++;
 	return 0;
 }