From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ursula Braun Subject: [PATCH net 2/3] s390/qeth: no ETH header for outbound AF_IUCV Date: Thu, 23 Mar 2017 14:55:09 +0100 Message-ID: <20170323135510.98972-3-ubraun@linux.vnet.ibm.com> References: <20170323135510.98972-1-ubraun@linux.vnet.ibm.com> Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, jwi@linux.vnet.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, raspl@linux.vnet.ibm.com, ubraun@linux.vnet.ibm.com To: davem@davemloft.net Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49646 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755860AbdCWNzY (ORCPT ); Thu, 23 Mar 2017 09:55:24 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v2NDrr9H145133 for ; Thu, 23 Mar 2017 09:55:23 -0400 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0b-001b2d01.pphosted.com with ESMTP id 29bxj17rxy-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 23 Mar 2017 09:55:22 -0400 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 23 Mar 2017 13:55:20 -0000 In-Reply-To: <20170323135510.98972-1-ubraun@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Julian Wiedmann With AF_IUCV traffic, the skb passed to hard_start_xmit() has a 14 byte slot at skb->data, intended for an ETH header. qeth_l3_fill_af_iucv_hdr() fills this ETH header... and then immediately moves it to the skb's headroom, where it disappears and is never seen again. But it's still possible for us to return NETDEV_TX_BUSY after the skb has been modified. Since we didn't get a private copy of the skb, the next time the skb is delivered to hard_start_xmit() it no longer has the expected layout (we moved the ETH header to the headroom, so skb->data now starts at the IUCV_TRANS header). So when qeth_l3_fill_af_iucv_hdr() does another round of rebuilding, the resulting qeth header ends up all wrong. On transmission, the buffer is then rejected by the HiperSockets device with SBALF15 = x'04'. When this error is passed back to af_iucv as TX_NOTIFY_UNREACHABLE, it tears down the offending socket. As the ETH header for AF_IUCV serves no purpose, just align the code to what we do for IP traffic on L3 HiperSockets: keep the ETH header at skb->data, and pass down data_offset = ETH_HLEN to qeth_fill_buffer(). When mapping the payload into the SBAL elements, the ETH header is then stripped off. This avoids the skb manipulations in qeth_l3_fill_af_iucv_hdr(), and any buffer re-entering hard_start_xmit() after NETDEV_TX_BUSY is now processed properly. Signed-off-by: Julian Wiedmann Signed-off-by: Ursula Braun --- drivers/s390/net/qeth_l3_main.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c index 72aa953..653f0fb 100644 --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -2609,17 +2609,13 @@ static void qeth_l3_fill_af_iucv_hdr(struct qeth_card *card, char daddr[16]; struct af_iucv_trans_hdr *iucv_hdr; - skb_pull(skb, 14); - card->dev->header_ops->create(skb, card->dev, 0, - card->dev->dev_addr, card->dev->dev_addr, - card->dev->addr_len); - skb_pull(skb, 14); - iucv_hdr = (struct af_iucv_trans_hdr *)skb->data; memset(hdr, 0, sizeof(struct qeth_hdr)); hdr->hdr.l3.id = QETH_HEADER_TYPE_LAYER3; hdr->hdr.l3.ext_flags = 0; - hdr->hdr.l3.length = skb->len; + hdr->hdr.l3.length = skb->len - ETH_HLEN; hdr->hdr.l3.flags = QETH_HDR_IPV6 | QETH_CAST_UNICAST; + + iucv_hdr = (struct af_iucv_trans_hdr *) (skb->data + ETH_HLEN); memset(daddr, 0, sizeof(daddr)); daddr[0] = 0xfe; daddr[1] = 0x80; @@ -2823,10 +2819,7 @@ static int qeth_l3_hard_start_xmit(struct sk_buff *skb, struct net_device *dev) if ((card->info.type == QETH_CARD_TYPE_IQD) && !skb_is_nonlinear(skb)) { new_skb = skb; - if (new_skb->protocol == ETH_P_AF_IUCV) - data_offset = 0; - else - data_offset = ETH_HLEN; + data_offset = ETH_HLEN; hdr = kmem_cache_alloc(qeth_core_header_cache, GFP_ATOMIC); if (!hdr) goto tx_drop; -- 2.8.4