From mboxrd@z Thu Jan 1 00:00:00 1970 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 D23E9C001B0 for ; Tue, 15 Aug 2023 16:29:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238466AbjHOQ3S (ORCPT ); Tue, 15 Aug 2023 12:29:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238464AbjHOQ3L (ORCPT ); Tue, 15 Aug 2023 12:29:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD92D10D1 for ; Tue, 15 Aug 2023 09:29:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 59A9B65D79 for ; Tue, 15 Aug 2023 16:29:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11B2BC433C7; Tue, 15 Aug 2023 16:29:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1692116948; bh=krOcIuYg6hTWBjxkHEr41A9L5hn7EMMeN3KZMz9T4/s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YCy8JKSO1z40r0lqXc5NJ4zx1Hau50O6Va6z+rH9c25QJ8IwxSTLUjzw24S+Y/LkE YQmKU1N2xE3wgbSS8yqsYMncYfoSjtAbL1CufmXrTq5Ep3ER8MGlvYeLU9fA8jKlue ZrpR9KHOBf1WKRaWAA7xg+q6Hxdmzna603eGjrnnHYSapnftb37cailf8E4zqynBoD 8nA9Z47QZDc7RuBaSWEtIsbSJ6TKHhLZxa9Eot///l+/8GrJdz14GPNMyVLqwtTCTe Bhifeo1e5KpqqH0peU+/C1ZZo79+Ibp9NjzuzgKvB4HTHzn8Y45CWfkXhIs+mwk7sm GIf8brhD1ra+g== Date: Tue, 15 Aug 2023 18:29:03 +0200 From: Simon Horman To: Feng Liu Cc: Simon Horman , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jason Wang , "Michael S . Tsirkin" , Xuan Zhuo , Bodong Wang , Jiri Pirko , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Subject: Re: [PATCH net v1] virtio_net: Introduce skb_vnet_common_hdr to avoid typecasting Message-ID: References: <20230814171845.65930-1-feliu@nvidia.com> <05348d62-586c-4b1f-40bd-5541caca0947@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <05348d62-586c-4b1f-40bd-5541caca0947@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 15, 2023 at 11:09:02AM -0400, Feng Liu wrote: > > > On 2023-08-15 a.m.6:51, Simon Horman wrote: > > External email: Use caution opening links or attachments > > > > > > On Mon, Aug 14, 2023 at 01:18:45PM -0400, Feng Liu wrote: > > > > + "David S. Miller" > > Eric Dumazet > > Jakub Kicinski > > Paolo Abeni > > > Thanks for adding David S. Miller. > > > > The virtio_net driver currently deals with different versions and types > > > of virtio net headers, such as virtio_net_hdr_mrg_rxbuf, > > > virtio_net_hdr_v1_hash, etc. Due to these variations, the code relies > > > on multiple type casts to convert memory between different structures, > > > potentially leading to bugs when there are changes in these structures. > > > > > > Introduces the "struct skb_vnet_common_hdr" as a unifying header > > > structure using a union. With this approach, various virtio net header > > > structures can be converted by accessing different members of this > > > structure, thus eliminating the need for type casting and reducing the > > > risk of potential bugs. > > > > > > For example following code: > > > static struct sk_buff *page_to_skb(struct virtnet_info *vi, > > > struct receive_queue *rq, > > > struct page *page, unsigned int offset, > > > unsigned int len, unsigned int truesize, > > > unsigned int headroom) > > > { > > > [...] > > > struct virtio_net_hdr_mrg_rxbuf *hdr; > > > [...] > > > hdr_len = vi->hdr_len; > > > [...] > > > ok: > > > hdr = skb_vnet_hdr(skb); > > > memcpy(hdr, hdr_p, hdr_len); > > > [...] > > > } > > > > > > When VIRTIO_NET_F_HASH_REPORT feature is enabled, hdr_len = 20 > > > But the sizeof(*hdr) is 12, > > > memcpy(hdr, hdr_p, hdr_len); will copy 20 bytes to the hdr, > > > which make a potential risk of bug. And this risk can be avoided by > > > introducing struct virtio_net_hdr_mrg_rxbuf. > > > > > > Signed-off-by: Feng Liu > > > Reviewed-by: Jiri Pirko > > > > I'm unsure if this is 'net' material. > > > > It is about the modification of the virtio_net driver. I think it should be > regarded as `net` material. To clarify: In general new Networking features go via the net-next tree, while bug fixes go via the net tree. I was suggesting this is more appropriate for net-next, and that should be reflected in the subject. Subject: [PATCH net-next] ... Sorry for not being clearer the first time around. > > > > --- > > > drivers/net/virtio_net.c | 29 ++++++++++++++++------------- > > > include/uapi/linux/virtio_net.h | 7 +++++++ > > > 2 files changed, 23 insertions(+), 13 deletions(-) > > > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > > index 1270c8d23463..6ce0fbcabda9 100644 > > > --- a/drivers/net/virtio_net.c > > > +++ b/drivers/net/virtio_net.c > > > @@ -344,9 +344,10 @@ static int rxq2vq(int rxq) > > > return rxq * 2; > > > } > > > > > > -static inline struct virtio_net_hdr_mrg_rxbuf *skb_vnet_hdr(struct sk_buff *skb) > > > +static inline struct virtio_net_common_hdr * > > > +skb_vnet_common_hdr(struct sk_buff *skb) > > > { > > > - return (struct virtio_net_hdr_mrg_rxbuf *)skb->cb; > > > + return (struct virtio_net_common_hdr *)skb->cb; > > > } > > > > > > /* > > > @@ -469,7 +470,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, > > > unsigned int headroom) > > > { > > > struct sk_buff *skb; > > > - struct virtio_net_hdr_mrg_rxbuf *hdr; > > > + struct virtio_net_common_hdr *hdr; > > > unsigned int copy, hdr_len, hdr_padded_len; > > > struct page *page_to_free = NULL; > > > int tailroom, shinfo_size; > > > @@ -554,7 +555,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, > > > give_pages(rq, page); > > > > > > ok: > > > - hdr = skb_vnet_hdr(skb); > > > + hdr = skb_vnet_common_hdr(skb); > > > memcpy(hdr, hdr_p, hdr_len); > > > if (page_to_free) > > > put_page(page_to_free); > > > @@ -966,7 +967,7 @@ static struct sk_buff *receive_small_build_skb(struct virtnet_info *vi, > > > return NULL; > > > > > > buf += header_offset; > > > - memcpy(skb_vnet_hdr(skb), buf, vi->hdr_len); > > > + memcpy(skb_vnet_common_hdr(skb), buf, vi->hdr_len); > > > > > > return skb; > > > } > > > @@ -1577,7 +1578,8 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, > > > { > > > struct net_device *dev = vi->dev; > > > struct sk_buff *skb; > > > - struct virtio_net_hdr_mrg_rxbuf *hdr; > > > + struct virtio_net_common_hdr *common_hdr; > > > + struct virtio_net_hdr_mrg_rxbuf *mrg_hdr; > > > > > > if (unlikely(len < vi->hdr_len + ETH_HLEN)) { > > > pr_debug("%s: short packet %i\n", dev->name, len); > > > @@ -1597,18 +1599,19 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, > > > if (unlikely(!skb)) > > > return; > > > > > > - hdr = skb_vnet_hdr(skb); > > > + common_hdr = skb_vnet_common_hdr(skb); > > > if (dev->features & NETIF_F_RXHASH && vi->has_rss_hash_report) > > > - virtio_skb_set_hash((const struct virtio_net_hdr_v1_hash *)hdr, skb); > > > + virtio_skb_set_hash(&common_hdr->hash_v1_hdr, skb); > > > > > > - if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID) > > > + mrg_hdr = &common_hdr->mrg_hdr; > > > + if (mrg_hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID) > > > skb->ip_summed = CHECKSUM_UNNECESSARY; > > > > > > - if (virtio_net_hdr_to_skb(skb, &hdr->hdr, > > > + if (virtio_net_hdr_to_skb(skb, &mrg_hdr->hdr, > > > virtio_is_little_endian(vi->vdev))) { > > > net_warn_ratelimited("%s: bad gso: type: %u, size: %u\n", > > > - dev->name, hdr->hdr.gso_type, > > > - hdr->hdr.gso_size); > > > + dev->name, mrg_hdr->hdr.gso_type, > > > + mrg_hdr->hdr.gso_size); > > > goto frame_err; > > > } > > > > > > @@ -2105,7 +2108,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb) > > > if (can_push) > > > hdr = (struct virtio_net_hdr_mrg_rxbuf *)(skb->data - hdr_len); > > > else > > > - hdr = skb_vnet_hdr(skb); > > > + hdr = &skb_vnet_common_hdr(skb)->mrg_hdr; > > > > > > if (virtio_net_hdr_from_skb(skb, &hdr->hdr, > > > virtio_is_little_endian(vi->vdev), false, > > > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h > > > index 12c1c9699935..db40f93ae8b3 100644 > > > --- a/include/uapi/linux/virtio_net.h > > > +++ b/include/uapi/linux/virtio_net.h > > > @@ -201,6 +201,13 @@ struct virtio_net_hdr_mrg_rxbuf { > > > struct virtio_net_hdr hdr; > > > __virtio16 num_buffers; /* Number of merged rx buffers */ > > > }; > > > + > > > +struct virtio_net_common_hdr { > > > + union { > > > + struct virtio_net_hdr_mrg_rxbuf mrg_hdr; > > > + struct virtio_net_hdr_v1_hash hash_v1_hdr; > > > + }; > > > +}; > > > > Does this belong in the UAPI? > > I would have assumed it's a Kernel implementation detail. > > > The existing codes, virtio_net.h is in uapi/linux/, I added the new > structure and followed existing code. My modification is related to Kernel > implementation detail now. The header you have modified forms part of the userspace API (UAPI). Perhaps there is something about virtio_net that makes this correct, but it seems to me that kernel-internal details don't belong there. > > > > #endif /* ...VIRTIO_NET_NO_LEGACY */ > > > > > > /* > > > -- > > > 2.37.1 (Apple Git-137.1) > > > > > > >