From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757073AbdLVIvC (ORCPT ); Fri, 22 Dec 2017 03:51:02 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33918 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757026AbdLVIu4 (ORCPT ); Fri, 22 Dec 2017 03:50:56 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Julian Wiedmann , Ursula Braun , "David S. Miller" , Sasha Levin Subject: [PATCH 4.4 40/78] s390/qeth: no ETH header for outbound AF_IUCV Date: Fri, 22 Dec 2017 09:46:21 +0100 Message-Id: <20171222084601.426643285@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171222084556.909780563@linuxfoundation.org> References: <20171222084556.909780563@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Julian Wiedmann [ Upstream commit acd9776b5c45ef02d1a210969a6fcc058afb76e3 ] 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 Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/s390/net/qeth_l3_main.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -2680,17 +2680,13 @@ static void qeth_l3_fill_af_iucv_hdr(str 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; @@ -2873,10 +2869,7 @@ static int qeth_l3_hard_start_xmit(struc if ((card->info.type == QETH_CARD_TYPE_IQD) && (!large_send) && (skb_shinfo(skb)->nr_frags == 0)) { 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;