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From: Jason Wang <jasowang@redhat.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: netdev@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	john.fastabend@gmail.com, linux-kernel@vger.kernel.org,
	mst@redhat.com
Subject: Re: [PATCH net-next 0/2] virtio-net: re enable XDP_REDIRECT for mergeable buffer
Date: Thu, 1 Mar 2018 17:23:37 +0800	[thread overview]
Message-ID: <b0f55100-183d-a507-8510-3c67f6106031__20961.1770966605$1519896140$gmane$org@redhat.com> (raw)
In-Reply-To: <20180301101038.4253424d@redhat.com>



On 2018年03月01日 17:10, Jesper Dangaard Brouer wrote:
> On Thu,  1 Mar 2018 11:19:03 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> This series tries to re-enable XDP_REDIRECT for mergeable buffer which
>> was removed since commit 7324f5399b06 ("virtio_net: disable
>> XDP_REDIRECT in receive_mergeable() case"). Main concerns are:
>>
>> - not enough tailroom was reserved which breaks cpumap
> To address this at a more fundamental level, I would suggest that we/you
> instead extend XDP to know it's buffers "frame" size/end.  (The
> assumption use to be, xdp_buff->data_hard_start + PAGE_SIZE, but
> ixgbe+virtio_net broke that assumption).
>
> It should actually be fairly easy to implement:
>   * Simply extend xdp_buff with a "data_hard_end" pointer.

Right, and then cpumap can warn and drop packets with insufficient 
tailroom. But it should be a patch on top of this I think.

Thanks

>
> Now cpumap is more safe... instead of crashing, it can now know/see when
> it is safe to create an SKB using build_skb (could fallback to
> dev_alloc_skb).
>

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  reply	other threads:[~2018-03-01  9:23 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-01  3:19 [PATCH net-next 0/2] virtio-net: re enable XDP_REDIRECT for mergeable buffer Jason Wang
2018-03-01  3:19 ` Jason Wang
2018-03-01  3:19 ` [PATCH net-next 1/2] " Jason Wang
2018-03-01  3:19 ` Jason Wang
2018-03-01  8:41   ` Jesper Dangaard Brouer
2018-03-01  8:41   ` Jesper Dangaard Brouer
2018-03-01  9:11     ` Jason Wang
2018-03-01  9:11       ` Jason Wang
2018-03-01 13:36   ` Michael S. Tsirkin
2018-03-01 13:36     ` Michael S. Tsirkin
2018-03-02  4:20     ` Jason Wang
2018-03-02  4:20       ` Jason Wang
2018-03-01  3:19 ` [PATCH net-next 2/2] virtio-net: simplify XDP handling in small buffer Jason Wang
2018-03-01  8:02   ` Jesper Dangaard Brouer
2018-03-01  8:02   ` Jesper Dangaard Brouer
2018-03-01  8:49     ` Jason Wang
2018-03-01  9:15       ` Jesper Dangaard Brouer
2018-03-01  9:15         ` Jesper Dangaard Brouer
2018-03-01  9:24         ` Jason Wang
2018-03-01  9:24         ` Jason Wang
2018-03-01  8:49     ` Jason Wang
2018-03-01  3:19 ` Jason Wang
2018-03-01  9:10 ` [PATCH net-next 0/2] virtio-net: re enable XDP_REDIRECT for mergeable buffer Jesper Dangaard Brouer
2018-03-01  9:10   ` Jesper Dangaard Brouer
2018-03-01  9:23   ` Jason Wang [this message]
2018-03-01  9:23   ` Jason Wang
2018-03-01 10:35     ` Jesper Dangaard Brouer
2018-03-01 10:35       ` Jesper Dangaard Brouer
2018-03-01 13:15       ` Jason Wang
2018-03-01 14:16         ` Jesper Dangaard Brouer
2018-03-01 14:16           ` Jesper Dangaard Brouer
2018-03-02  4:17           ` Jason Wang
2018-03-02  4:17             ` Jason Wang
2018-03-01 13:15       ` Jason Wang
2018-03-01 13:40       ` Michael S. Tsirkin
2018-03-01 13:40         ` Michael S. Tsirkin

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