From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ursula Braun Subject: [PATCH net 1/1] net/af_iucv: don't use paged skbs for TX on HiperSockets Date: Tue, 10 Jan 2017 17:10:34 +0100 Message-ID: <20170110161034.82445-2-ubraun@linux.vnet.ibm.com> References: <20170110161034.82445-1-ubraun@linux.vnet.ibm.com> Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, stable@vger.kernel.org, ubraun@linux.vnet.ibm.com To: davem@davemloft.net Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33523 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030792AbdAJQKp (ORCPT ); Tue, 10 Jan 2017 11:10:45 -0500 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id v0AG4heH076139 for ; Tue, 10 Jan 2017 11:10:44 -0500 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 27w1s6bdyy-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 10 Jan 2017 11:10:44 -0500 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 10 Jan 2017 16:10:42 -0000 In-Reply-To: <20170110161034.82445-1-ubraun@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Julian Wiedmann With commit e53743994e21 ("af_iucv: use paged SKBs for big outbound messages"), we transmit paged skbs for both of AF_IUCV's transport modes (IUCV or HiperSockets). The qeth driver for Layer 3 HiperSockets currently doesn't support NETIF_F_SG, so these skbs would just be linearized again by the stack. Avoid that overhead by using paged skbs only for IUCV transport. cc stable, since this also circumvents a significant skb leak when sending large messages (where the skb then needs to be linearized). Signed-off-by: Julian Wiedmann Signed-off-by: Ursula Braun Cc: # v4.8+ Fixes: e53743994e21 ("af_iucv: use paged SKBs for big outbound messages") --- net/iucv/af_iucv.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c index cfb9e5f..13190b3 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -1044,7 +1044,8 @@ static int iucv_sock_sendmsg(struct socket *sock, struct msghdr *msg, { struct sock *sk = sock->sk; struct iucv_sock *iucv = iucv_sk(sk); - size_t headroom, linear; + size_t headroom = 0; + size_t linear; struct sk_buff *skb; struct iucv_message txmsg = {0}; struct cmsghdr *cmsg; @@ -1122,18 +1123,20 @@ static int iucv_sock_sendmsg(struct socket *sock, struct msghdr *msg, * this is fine for SOCK_SEQPACKET (unless we want to support * segmented records using the MSG_EOR flag), but * for SOCK_STREAM we might want to improve it in future */ - headroom = (iucv->transport == AF_IUCV_TRANS_HIPER) - ? sizeof(struct af_iucv_trans_hdr) + ETH_HLEN : 0; - if (headroom + len < PAGE_SIZE) { + if (iucv->transport == AF_IUCV_TRANS_HIPER) { + headroom = sizeof(struct af_iucv_trans_hdr) + ETH_HLEN; linear = len; } else { - /* In nonlinear "classic" iucv skb, - * reserve space for iucv_array - */ - if (iucv->transport != AF_IUCV_TRANS_HIPER) - headroom += sizeof(struct iucv_array) * - (MAX_SKB_FRAGS + 1); - linear = PAGE_SIZE - headroom; + if (len < PAGE_SIZE) { + linear = len; + } else { + /* In nonlinear "classic" iucv skb, + * reserve space for iucv_array + */ + headroom = sizeof(struct iucv_array) * + (MAX_SKB_FRAGS + 1); + linear = PAGE_SIZE - headroom; + } } skb = sock_alloc_send_pskb(sk, headroom + linear, len - linear, noblock, &err, 0); -- 2.8.4