From patchwork Wed Mar 15 04:10:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 13175280 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FF24C61DA4 for ; Wed, 15 Mar 2023 04:10:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230451AbjCOEK5 (ORCPT ); Wed, 15 Mar 2023 00:10:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230458AbjCOEKx (ORCPT ); Wed, 15 Mar 2023 00:10:53 -0400 Received: from out30-124.freemail.mail.aliyun.com (out30-124.freemail.mail.aliyun.com [115.124.30.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFADF4A1FB; Tue, 14 Mar 2023 21:10:47 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045176;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=13;SR=0;TI=SMTPD_---0Vdui0Om_1678853444; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0Vdui0Om_1678853444) by smtp.aliyun-inc.com; Wed, 15 Mar 2023 12:10:44 +0800 From: Xuan Zhuo To: netdev@vger.kernel.org Cc: "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux-foundation.org, bpf@vger.kernel.org Subject: [RFC net-next 1/8] virtio_net: mergeable xdp: put old page immediately Date: Wed, 15 Mar 2023 12:10:35 +0800 Message-Id: <20230315041042.88138-2-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20230315041042.88138-1-xuanzhuo@linux.alibaba.com> References: <20230315041042.88138-1-xuanzhuo@linux.alibaba.com> MIME-Version: 1.0 X-Git-Hash: a046238c058f Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC In the xdp implementation of virtio-net mergeable, it always checks whether two page is used and a page is selected to release. This is complicated for the processing of action, and be careful. In the entire process, we have such principles: * If xdp_page is used (PASS, TX, Redirect), then we release the old page. * If it is a drop case, we will release two. The old page obtained from buf is release inside err_xdp, and xdp_page needs be relased by us. But in fact, when we allocate a new page, we can release the old page immediately. Then just one is using, we just need to release the new page for drop case. On the drop path, err_xdp will release the variable "page", so we only need to let "page" point to the new xdp_page in advance. Signed-off-by: Xuan Zhuo --- drivers/net/virtio_net.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 6e88c023cdcc..36be30319660 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1175,6 +1175,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, if (!xdp_page) goto err_xdp; offset = VIRTIO_XDP_HEADROOM; + + put_page(page); + page = xdp_page; } else if (unlikely(headroom < virtnet_get_headroom(vi))) { xdp_room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM + sizeof(struct skb_shared_info)); @@ -1189,6 +1192,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, page_address(page) + offset, len); frame_sz = PAGE_SIZE; offset = VIRTIO_XDP_HEADROOM; + + put_page(page); + page = xdp_page; } else { xdp_page = page; } @@ -1208,8 +1214,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, if (unlikely(!head_skb)) goto err_xdp_frags; - if (unlikely(xdp_page != page)) - put_page(page); rcu_read_unlock(); return head_skb; case XDP_TX: @@ -1227,8 +1231,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, goto err_xdp_frags; } *xdp_xmit |= VIRTIO_XDP_TX; - if (unlikely(xdp_page != page)) - put_page(page); rcu_read_unlock(); goto xdp_xmit; case XDP_REDIRECT: @@ -1237,8 +1239,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, if (err) goto err_xdp_frags; *xdp_xmit |= VIRTIO_XDP_REDIR; - if (unlikely(xdp_page != page)) - put_page(page); rcu_read_unlock(); goto xdp_xmit; default: @@ -1251,9 +1251,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, goto err_xdp_frags; } err_xdp_frags: - if (unlikely(xdp_page != page)) - __free_pages(xdp_page, 0); - if (xdp_buff_has_frags(&xdp)) { shinfo = xdp_get_shared_info_from_buff(&xdp); for (i = 0; i < shinfo->nr_frags; i++) {