From patchwork Wed Sep 12 03:17:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 10596697 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8B98613B8 for ; Wed, 12 Sep 2018 03:18:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7AD3429BEF for ; Wed, 12 Sep 2018 03:18:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6F59F29BF8; Wed, 12 Sep 2018 03:18:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1816A29BEF for ; Wed, 12 Sep 2018 03:18:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728139AbeILIUL (ORCPT ); Wed, 12 Sep 2018 04:20:11 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:55766 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728125AbeILIUK (ORCPT ); Wed, 12 Sep 2018 04:20:10 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 87F6B87A72; Wed, 12 Sep 2018 03:17:46 +0000 (UTC) Received: from jason-ThinkPad-T450s.redhat.com (ovpn-12-130.pek2.redhat.com [10.72.12.130]) by smtp.corp.redhat.com (Postfix) with ESMTP id DF7102027EA4; Wed, 12 Sep 2018 03:17:41 +0000 (UTC) From: Jason Wang To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, mst@redhat.com, jasowang@redhat.com Subject: [PATCH net-next V2 05/11] tuntap: tweak on the path of skb XDP case in tun_build_skb() Date: Wed, 12 Sep 2018 11:17:03 +0800 Message-Id: <20180912031709.14112-6-jasowang@redhat.com> In-Reply-To: <20180912031709.14112-1-jasowang@redhat.com> References: <20180912031709.14112-1-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Wed, 12 Sep 2018 03:17:46 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Wed, 12 Sep 2018 03:17:46 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jasowang@redhat.com' RCPT:'' Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If we're sure not to go native XDP, there's no need for several things like bh and rcu stuffs. So this patch introduces a helper to build skb and hold page refcnt. When we found we will go through skb path, build skb directly. Signed-off-by: Jason Wang --- drivers/net/tun.c | 39 ++++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 15 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 257cf7342d54..946c6148ed75 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1635,6 +1635,23 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile, return true; } +static struct sk_buff *__tun_build_skb(struct page_frag *alloc_frag, char *buf, + int buflen, int len, int pad, int delta) +{ + struct sk_buff *skb = build_skb(buf, buflen); + + if (!skb) + return ERR_PTR(-ENOMEM); + + skb_reserve(skb, pad - delta); + skb_put(skb, len); + + get_page(alloc_frag->page); + alloc_frag->offset += buflen; + + return skb; +} + static struct sk_buff *tun_build_skb(struct tun_struct *tun, struct tun_file *tfile, struct iov_iter *from, @@ -1642,7 +1659,6 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, int len, int *skb_xdp) { struct page_frag *alloc_frag = ¤t->task_frag; - struct sk_buff *skb; struct bpf_prog *xdp_prog; int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); unsigned int delta = 0; @@ -1672,10 +1688,12 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, * of xdp_prog above, this should be rare and for simplicity * we do XDP on skb in case the headroom is not enough. */ - if (hdr->gso_type || !xdp_prog) + if (hdr->gso_type || !xdp_prog) { *skb_xdp = 1; - else - *skb_xdp = 0; + return __tun_build_skb(alloc_frag, buf, buflen, len, pad, delta); + } + + *skb_xdp = 0; local_bh_disable(); rcu_read_lock(); @@ -1719,22 +1737,13 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, trace_xdp_exception(tun->dev, xdp_prog, act); /* fall through */ case XDP_DROP: - goto err_xdp; + goto out; } } rcu_read_unlock(); local_bh_enable(); - skb = build_skb(buf, buflen); - if (!skb) - return ERR_PTR(-ENOMEM); - - skb_reserve(skb, pad - delta); - skb_put(skb, len); - get_page(alloc_frag->page); - alloc_frag->offset += buflen; - - return skb; + return __tun_build_skb(alloc_frag, buf, buflen, len, pad, delta); err_redirect: put_page(alloc_frag->page);