From: Julian Wiedmann <jwi@linux.ibm.com>
Subject: s390/qeth: clean up page frag creation
Patch-mainline: v4.15-rc1
Git-commit: b6f72f9698ab8bd79cd0b72a8d9f25dacd786563
References: FATE#326350, LTC#169511, bsc#1113509

Summary:     qeth: performance improvements
Description: This adds recent functional and performance improvements for the
             qeth network driver.
             Primarily this brings Scatter-Gather support for HiperSockets,
             reduced CPU consumption in the L3 IPv4 transmit path for OSA,
             improved Promiscuous Mode performance due to IFF_UNICAST_FLT,
             support for Scatter-Gather on z/VM virtual NICs, and
             support for delayed GRO flushing.

             For sanity & stability reasons, this effectively constitutes a
             backport of the qeth device driver from 4.19 mainline.
             

Upstream-Description:

             s390/qeth: clean up page frag creation

             Replace the open-coded skb_add_rx_frag(), and use a fall-through
             to remove some duplicated code.

             Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
             Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/net/qeth_core_main.c |   31 +++++++++++--------------------
 1 file changed, 11 insertions(+), 20 deletions(-)

--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -5189,10 +5189,11 @@ EXPORT_SYMBOL_GPL(qeth_core_hardsetup_ca
 
 static int qeth_create_skb_frag(struct qeth_qdio_buffer *qethbuffer,
 				struct qdio_buffer_element *element,
-				struct sk_buff **pskb, int offset, int *pfrag,
-				int data_len)
+				struct sk_buff **pskb, int offset, int data_len)
 {
 	struct page *page = virt_to_page(element->addr);
+	unsigned int next_frag;
+
 	if (*pskb == NULL) {
 		if (qethbuffer->rx_skb) {
 			/* only if qeth_card.options.cq == QETH_CQ_ENABLED */
@@ -5207,28 +5208,19 @@ static int qeth_create_skb_frag(struct q
 		skb_reserve(*pskb, ETH_HLEN);
 		if (data_len <= QETH_RX_PULL_LEN) {
 			skb_put_data(*pskb, element->addr + offset, data_len);
+			return 0;
 		} else {
-			get_page(page);
 			skb_put_data(*pskb, element->addr + offset,
 				     QETH_RX_PULL_LEN);
-			skb_fill_page_desc(*pskb, *pfrag, page,
-				offset + QETH_RX_PULL_LEN,
-				data_len - QETH_RX_PULL_LEN);
-			(*pskb)->data_len += data_len - QETH_RX_PULL_LEN;
-			(*pskb)->len      += data_len - QETH_RX_PULL_LEN;
-			(*pskb)->truesize += data_len - QETH_RX_PULL_LEN;
-			(*pfrag)++;
+			data_len -= QETH_RX_PULL_LEN;
+			offset += QETH_RX_PULL_LEN;
+			/* fall through to add page frag for remaining data */
 		}
-	} else {
-		get_page(page);
-		skb_fill_page_desc(*pskb, *pfrag, page, offset, data_len);
-		(*pskb)->data_len += data_len;
-		(*pskb)->len      += data_len;
-		(*pskb)->truesize += data_len;
-		(*pfrag)++;
 	}
 
-
+	next_frag = skb_shinfo(*pskb)->nr_frags;
+	get_page(page);
+	skb_add_rx_frag(*pskb, next_frag, page, offset, data_len, data_len);
 	return 0;
 }
 
@@ -5251,7 +5243,6 @@ struct sk_buff *qeth_core_get_next_skb(s
 	int data_len;
 	int headroom = 0;
 	int use_rx_sg = 0;
-	int frag = 0;
 
 	/* qeth_hdr must not cross element boundaries */
 	if (element->length < offset + sizeof(struct qeth_hdr)) {
@@ -5303,7 +5294,7 @@ struct sk_buff *qeth_core_get_next_skb(s
 		if (data_len) {
 			if (use_rx_sg) {
 				if (qeth_create_skb_frag(qethbuffer, element,
-				    &skb, offset, &frag, data_len))
+				    &skb, offset, data_len))
 					goto no_mem;
 			} else {
 				skb_put_data(skb, data_ptr, data_len);