> -----Original Message-----
> From: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> Sent: Thursday, July 23, 2020 2:42 PM
> To: netdev@xxxxxxxxxxxxxxx
> Cc: bpf@xxxxxxxxxxxxxxx; davem@xxxxxxxxxxxxx; ast@xxxxxxxxxx;
> brouer@xxxxxxxxxx; daniel@xxxxxxxxxxxxx; lorenzo.bianconi@xxxxxxxxxx;
> echaudro@xxxxxxxxxx; Jubran, Samih <sameehj@xxxxxxxxxx>;
> kuba@xxxxxxxxxx
> Subject: [EXTERNAL] [RFC net-next 01/22] xdp: introduce mb in
> xdp_buff/xdp_frame
>
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>
>
> Introduce multi-buffer bit (mb) in xdp_frame/xdp_buffer to specify if
> shared_info area has been properly initialized for non-linear xdp buffers
>
> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> ---
> include/net/xdp.h | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/xdp.h b/include/net/xdp.h index
> dbe9c60797e1..2ef6935c5646 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -72,7 +72,8 @@ struct xdp_buff {
> void *data_hard_start;
> struct xdp_rxq_info *rxq;
> struct xdp_txq_info *txq;
> - u32 frame_sz; /* frame size to deduce data_hard_end/reserved
> tailroom*/
> + u32 frame_sz:31; /* frame size to deduce data_hard_end/reserved
> tailroom*/
It seems strange that you assign a 32 sized field to a 24 sized field.
Wouldn't it be better if we used the same size in all places?
> + u32 mb:1; /* xdp non-linear buffer */
> };
>
> /* Reserve memory area at end-of data area.
> @@ -96,7 +97,8 @@ struct xdp_frame {
> u16 len;
> u16 headroom;
> u32 metasize:8;
> - u32 frame_sz:24;
> + u32 frame_sz:23;
> + u32 mb:1; /* xdp non-linear frame */
> /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
> * while mem info is valid on remote CPU.
> */
> @@ -141,6 +143,7 @@ void xdp_convert_frame_to_buff(struct xdp_frame
> *frame, struct xdp_buff *xdp)
> xdp->data_end = frame->data + frame->len;
> xdp->data_meta = frame->data - frame->metasize;
> xdp->frame_sz = frame->frame_sz;
> + xdp->mb = frame->mb;
> }
>
> static inline
> @@ -167,6 +170,7 @@ int xdp_update_frame_from_buff(struct xdp_buff
> *xdp,
> xdp_frame->headroom = headroom - sizeof(*xdp_frame);
> xdp_frame->metasize = metasize;
> xdp_frame->frame_sz = xdp->frame_sz;
> + xdp_frame->mb = xdp->mb;
>
> return 0;
> }
> --
> 2.26.2
