> -----邮件原件-----
> 发件人: Magnus Karlsson [mailto:magnus.karls...@gmail.com]
> 发送时间: 2020年7月20日 15:21
> 收件人: Li,Rongqing <lirongq...@baidu.com>
> 抄送: Network Development <netdev@vger.kernel.org>; intel-wired-lan
> <intel-wired-...@lists.osuosl.org>; Karlsson, Magnus
> <magnus.karls...@intel.com>; Björn Töpel <bjorn.to...@intel.com>
> 主题: Re: [Intel-wired-lan] [PATCH 1/2] xdp: i40e: ixgbe: ixgbevf: not flip rx
> buffer for copy mode xdp
>
> On Fri, Jul 17, 2020 at 8:24 AM Li RongQing <lirongq...@baidu.com> wrote:
> >
> > i40e/ixgbe/ixgbevf_rx_buffer_flip in copy mode xdp can lead to data
> > corruption, like the following flow:
> >
> > 1. first skb is not for xsk, and forwarded to another device
> > or socket queue
> > 2. seconds skb is for xsk, copy data to xsk memory, and page
> > of skb->data is released
> > 3. rx_buff is reusable since only first skb is in it, but
> > *_rx_buffer_flip will make that page_offset is set to
> > first skb data
> > 4. then reuse rx buffer, first skb which still is living
> > will be corrupted.
e, but known size type */
> > u32 id;
> > @@ -73,6 +75,7 @@ struct xdp_buff {
> > struct xdp_rxq_info *rxq;
> > struct xdp_txq_info *txq;
> > u32 frame_sz; /* frame size to deduce data_hard_end/reserved
> > tailroom*/
> > + u32 flags;
>
> RongQing,
>
> Sorry that I was not clear enough. Could you please submit the simple patch
> you had, the one that only tests for the memory type.
>
> if (xdp->rxq->mem.type != MEM_TYPE_XSK_BUFF_POOL)
> i40e_rx_buffer_flip(rx_ring, rx_buffer, size);
>
> I do not think that adding a flags field in the xdp_mem_info to fix an Intel
> driver
> problem will be hugely popular. The struct is also meant to contain long lived
> information, not things that will frequently change.
>
Thank you Magnus
My original suggestion is wrong , it should be following
if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
i40e_rx_buffer_flip(rx_ring, rx_buffer, size);
but I feel it is not enough to only check mem.type, it must ensure that
map_type is BPF_MAP_TYPE_XSKMAP ? but it is not expose.
other maptype, like BPF_MAP_TYPE_DEVMAP, and if mem.type is
MEM_TYPE_PAGE_SHARED, not flip the rx buffer, will cause data corruption.
-Li
