From: Julian Wiedmann <jwi@linux.ibm.com>
Date: Mon, 23 Dec 2019 15:22:27 +0100
Subject: s390/qeth: remove QETH_RX_PULL_LEN
Git-commit: 8ca8559ff3cefd78e12b9658f21cc8bcc02407ec
Patch-mainline: v5.6-rc1
References: jsc#SLE-13690

Since commit f677fcb9aeb6 ("s390/qeth: ensure linear access to packet headers"),
the CQ-specific skbs are allocated with a slightly bigger linear part
than necessary. Shrink it down to the maximum that's needed by
qeth_extract_skb().

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/net/qeth_core.h      |    1 -
 drivers/s390/net/qeth_core_main.c |    6 ++++--
 2 files changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -221,7 +221,6 @@ struct qeth_vnicc_info {
 
 /* large receive scatter gather copy break */
 #define QETH_RX_SG_CB (PAGE_SIZE >> 1)
-#define QETH_RX_PULL_LEN 256
 
 struct qeth_hdr_layer3 {
 	__u8  id;
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -2623,7 +2623,8 @@ static int qeth_init_input_buffer(struct
 
 	if ((card->options.cq == QETH_CQ_ENABLED) && (!buf->rx_skb)) {
 		buf->rx_skb = netdev_alloc_skb(card->dev,
-					       QETH_RX_PULL_LEN + ETH_HLEN);
+					       ETH_HLEN +
+					       sizeof(struct ipv6hdr));
 		if (!buf->rx_skb)
 			return 1;
 	}
@@ -5253,7 +5254,8 @@ next_packet:
 
 	if (use_rx_sg) {
 		/* QETH_CQ_ENABLED only: */
-		if (qethbuffer->rx_skb) {
+		if (qethbuffer->rx_skb &&
+		    skb_tailroom(qethbuffer->rx_skb) >= linear_len + headroom) {
 			skb = qethbuffer->rx_skb;
 			qethbuffer->rx_skb = NULL;
 			goto use_skb;