From: Julian Wiedmann <jwi@linux.ibm.com>
Subject: s390/qeth: remove qeth_hdr_chk_and_bounce()
Patch-mainline: v4.20-rc1
Git-commit: 69d7ce80df6d0d2fdbb8f0ff9ec4643aabfa6b99
References: FATE#326377, LTC#169210, bsc#1115382

Summary:        qeth: Full-blown TCP Segmentation Offload
Description:    As of now, qeth only supports TCP Segmentation Offload (TSO)
                for IPv4 in Layer3 devices. This feature extends the existing
                support to IPv6, and adds support for TSO in both IP variants
                for Layer2.

                To cleanly pull in all the necessary changes to the transmit
                code, update the qeth driver to the current 4.20 level.


Upstream-Description:

             s390/qeth: remove qeth_hdr_chk_and_bounce()

             Restructure the OSN xmit path to handle misaligned HW headers properly,
             without shifting the packet data around.

             Signed-off-by: Julian Wiedmann <jwi@linux.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.h      |    1 -
 drivers/s390/net/qeth_core_main.c |   21 ---------------------
 drivers/s390/net/qeth_l2_main.c   |   37 ++++++++++++++++++++++++++++---------
 3 files changed, 28 insertions(+), 31 deletions(-)

--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -1020,7 +1020,6 @@ void qeth_dbf_longtext(debug_info_t *id,
 int qeth_core_ethtool_get_link_ksettings(struct net_device *netdev,
 					 struct ethtool_link_ksettings *cmd);
 int qeth_set_access_ctrl_online(struct qeth_card *card, int fallback);
-int qeth_hdr_chk_and_bounce(struct sk_buff *, struct qeth_hdr **, int);
 int qeth_configure_cq(struct qeth_card *, enum qeth_cq);
 int qeth_hw_trap(struct qeth_card *, enum qeth_diags_trap_action);
 void qeth_trace_features(struct qeth_card *);
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -3819,27 +3819,6 @@ unsigned int qeth_count_elements(struct
 }
 EXPORT_SYMBOL_GPL(qeth_count_elements);
 
-int qeth_hdr_chk_and_bounce(struct sk_buff *skb, struct qeth_hdr **hdr, int len)
-{
-	int hroom, inpage, rest;
-
-	if (((unsigned long)skb->data & PAGE_MASK) !=
-	    (((unsigned long)skb->data + len - 1) & PAGE_MASK)) {
-		hroom = skb_headroom(skb);
-		inpage = PAGE_SIZE - ((unsigned long) skb->data % PAGE_SIZE);
-		rest = len - inpage;
-		if (rest > hroom)
-			return 1;
-		memmove(skb->data - rest, skb->data, skb_headlen(skb));
-		skb->data -= rest;
-		skb->tail -= rest;
-		*hdr = (struct qeth_hdr *)skb->data;
-		QETH_DBF_MESSAGE(2, "skb bounce len: %d rest: %d\n", len, rest);
-	}
-	return 0;
-}
-EXPORT_SYMBOL_GPL(qeth_hdr_chk_and_bounce);
-
 #define QETH_HDR_CACHE_OBJ_SIZE		(sizeof(struct qeth_hdr_tso) + \
 					 MAX_TCP_HEADER)
 
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -650,19 +650,38 @@ static void qeth_l2_set_rx_mode(struct n
 static int qeth_l2_xmit_osn(struct qeth_card *card, struct sk_buff *skb,
 			    struct qeth_qdio_out_q *queue)
 {
-	unsigned int elements;
-	struct qeth_hdr *hdr;
+	struct qeth_hdr *hdr = (struct qeth_hdr *)skb->data;
+	addr_t end = (addr_t)(skb->data + sizeof(*hdr));
+	addr_t start = (addr_t)skb->data;
+	unsigned int elements = 0;
+	unsigned int hd_len = 0;
+	int rc;
 
 	if (skb->protocol == htons(ETH_P_IPV6))
 		return -EPROTONOSUPPORT;
 
-	hdr = (struct qeth_hdr *)skb->data;
-	elements = qeth_count_elements(skb, 0);
-	if (elements > QETH_MAX_BUFFER_ELEMENTS(card))
-		return -E2BIG;
-	if (qeth_hdr_chk_and_bounce(skb, &hdr, sizeof(*hdr)))
-		return -EINVAL;
-	return qeth_do_send_packet(card, queue, skb, hdr, 0, 0, elements);
+	if (qeth_get_elements_for_range(start, end) > 1) {
+		/* Misaligned HW header, move it to its own buffer element. */
+		hdr = kmem_cache_alloc(qeth_core_header_cache, GFP_ATOMIC);
+		if (!hdr)
+			return -ENOMEM;
+		hd_len = sizeof(*hdr);
+		skb_copy_from_linear_data(skb, (char *)hdr, hd_len);
+		elements++;
+	}
+
+	elements += qeth_count_elements(skb, hd_len);
+	if (elements > QETH_MAX_BUFFER_ELEMENTS(card)) {
+		rc = -E2BIG;
+		goto out;
+	}
+
+	rc = qeth_do_send_packet(card, queue, skb, hdr, hd_len, hd_len,
+				 elements);
+out:
+	if (rc && hd_len)
+		kmem_cache_free(qeth_core_header_cache, hdr);
+	return rc;
 }
 
 static netdev_tx_t qeth_l2_hard_start_xmit(struct sk_buff *skb,