On Thu, May 18, 2023 at 12:22 PM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote: > > On 05/18, Maciej Fijalkowski wrote: > > From: Tirthendu Sarkar <tirthendu.sarkar@xxxxxxxxx> > > > > Use the 'options' field in xdp_desc as a packet continuity marker. Since > > 'options' field was unused till now and was expected to be set to 0, the > > 'eop' descriptor will have it set to 0, while the non-eop descriptors > > will have to set it to 1. This ensures legacy applications continue to > > work without needing any change for single-buffer packets. > > > > Add helper functions and extend xskq_prod_reserve_desc() to use the > > 'options' field. > > > > Signed-off-by: Tirthendu Sarkar <tirthendu.sarkar@xxxxxxxxx> > > --- > > include/uapi/linux/if_xdp.h | 16 ++++++++++++++++ > > net/xdp/xsk.c | 8 ++++---- > > net/xdp/xsk_queue.h | 12 +++++++++--- > > 3 files changed, 29 insertions(+), 7 deletions(-) > > > > diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h > > index a78a8096f4ce..4acc3a9430f3 100644 > > --- a/include/uapi/linux/if_xdp.h > > +++ b/include/uapi/linux/if_xdp.h > > @@ -108,4 +108,20 @@ struct xdp_desc { > > > > /* UMEM descriptor is __u64 */ > > > > +/* Flag indicating that the packet continues with the buffer pointed out by the > > + * next frame in the ring. The end of the packet is signalled by setting this > > + * bit to zero. For single buffer packets, every descriptor has 'options' set > > + * to 0 and this maintains backward compatibility. > > + */ > > +#define XDP_PKT_CONTD (1 << 0) > > + > > +/* Maximum number of descriptors supported as frags for a packet. So the total > > + * number of descriptors supported for a packet is XSK_DESC_MAX_FRAGS + 1. The > > + * max frags supported by skb is 16 for page sizes greater than 4K and 17 or > > This is now a config option CONFIG_MAX_SKB_FRAGS. Can we use it > directly? Also it doesn't look right to expose kernel internal config in uapi especially since XSK_DESC_MAX_FRAGS is not guaranteed to be 16.