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From: Jason Wang <jasowang@redhat.com>
To: Jakub Kicinski <kuba@kernel.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	virtualization@lists.linux-foundation.org, bpf@vger.kernel.org
Subject: Re: [PATCH net v2 0/2] virtio-net: fix for build_skb()
Date: Mon, 2 Aug 2021 12:45:03 +0800	[thread overview]
Message-ID: <7ec67d98-190e-343d-bc2b-6f42a7ee6402@redhat.com> (raw)
In-Reply-To: <20210730051643.54198a9e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>


在 2021/7/30 下午8:16, Jakub Kicinski 写道:
> On Tue, 1 Jun 2021 07:06:43 -0400 Michael S. Tsirkin wrote:
>> On Tue, Jun 01, 2021 at 02:39:58PM +0800, Xuan Zhuo wrote:
>>> #1 Fixed a serious error.
>>> #2 Fixed a logical error, but this error did not cause any serious consequences.
>>>
>>> The logic of this piece is really messy. Fortunately, my refactored patch can be
>>> completed with a small amount of testing.
>> Looks good, thanks!
>> Also needed for stable I think.
>>
>> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> Just a heads up folks, looks like we ended up merging both this and the
> net-next version of the patch set:
>
> 8fb7da9e9907 virtio_net: get build_skb() buf by data ptr
> 5c37711d9f27 virtio-net: fix for unable to handle page fault for address
>
> and
>
> 7bf64460e3b2 virtio-net: get build_skb() buf by data ptr
> 6c66c147b9a4 virtio-net: fix for unable to handle page fault for address
>
> Are you okay with the code as is or should we commit something like:


I think we need commit the following codes since it's more easier to be 
understood.

Thanks


>
> ---
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 56c3f8519093..74482a52f076 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -380,7 +380,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
>   				   struct page *page, unsigned int offset,
>   				   unsigned int len, unsigned int truesize,
>   				   bool hdr_valid, unsigned int metasize,
> -				   bool whole_page)
> +				   unsigned int headroom)
>   {
>   	struct sk_buff *skb;
>   	struct virtio_net_hdr_mrg_rxbuf *hdr;
> @@ -398,28 +398,16 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
>   	else
>   		hdr_padded_len = sizeof(struct padded_vnet_hdr);
>   
> -	/* If whole_page, there is an offset between the beginning of the
> +	/* If headroom is not 0, there is an offset between the beginning of the
>   	 * data and the allocated space, otherwise the data and the allocated
>   	 * space are aligned.
>   	 *
>   	 * Buffers with headroom use PAGE_SIZE as alloc size, see
>   	 * add_recvbuf_mergeable() + get_mergeable_buf_len()
>   	 */
> -	if (whole_page) {
> -		/* Buffers with whole_page use PAGE_SIZE as alloc size,
> -		 * see add_recvbuf_mergeable() + get_mergeable_buf_len()
> -		 */
> -		truesize = PAGE_SIZE;
> -
> -		/* page maybe head page, so we should get the buf by p, not the
> -		 * page
> -		 */
> -		tailroom = truesize - len - offset_in_page(p);
> -		buf = (char *)((unsigned long)p & PAGE_MASK);
> -	} else {
> -		tailroom = truesize - len;
> -		buf = p;
> -	}
> +	truesize = headroom ? PAGE_SIZE : truesize;
> +	tailroom = truesize - len - headroom;
> +	buf = p - headroom;
>   
>   	len -= hdr_len;
>   	offset += hdr_padded_len;
> @@ -978,7 +966,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>   				put_page(page);
>   				head_skb = page_to_skb(vi, rq, xdp_page, offset,
>   						       len, PAGE_SIZE, false,
> -						       metasize, true);
> +						       metasize,
> +						       VIRTIO_XDP_HEADROOM);
>   				return head_skb;
>   			}
>   			break;
> @@ -1029,7 +1018,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>   	rcu_read_unlock();
>   
>   	head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog,
> -			       metasize, !!headroom);
> +			       metasize, headroom);
>   	curr_skb = head_skb;
>   
>   	if (unlikely(!curr_skb))
>


  reply	other threads:[~2021-08-02  4:45 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-01  6:39 Xuan Zhuo
2021-06-01  6:39 ` [PATCH net v2 1/2] virtio-net: fix for unable to handle page fault for address Xuan Zhuo
2021-06-01  8:53   ` Jason Wang
2021-06-01  6:40 ` [PATCH net v2 2/2] virtio_net: get build_skb() buf by data ptr Xuan Zhuo
2021-06-01  8:55   ` Jason Wang
2021-06-01 11:06 ` [PATCH net v2 0/2] virtio-net: fix for build_skb() Michael S. Tsirkin
2021-07-30 12:16   ` Jakub Kicinski
2021-08-02  4:45     ` Jason Wang [this message]
2021-08-02 16:58     ` Michael S. Tsirkin
2021-06-01 22:30 ` patchwork-bot+netdevbpf

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