The code piece which would attach a frag to &xdp_buff is almost identical across the drivers supporting XDP multi-buffer on Rx. Make it a generic elegant onelner. Also, I see lots of drivers calculating frags_truesize as `xdp->frame_sz * nr_frags`. I can't say this is fully correct, since frags might be backed by chunks of different sizes, especially with stuff like the header split. Even page_pool_alloc() can give you two different truesizes on two subsequent requests to allocate the same buffer size. Add a field to &skb_shared_info (unionized as there's no free slot currently on x6_64) to track the "true" truesize. It can be used later when updating an skb.
Signed-off-by: Alexander Lobakin <[email protected]> --- include/linux/skbuff.h | 14 ++++++++++---- include/net/xdp.h | 36 +++++++++++++++++++++++++++++++++++- 2 files changed, 45 insertions(+), 5 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index ea5c8ab3ed00..e350efa04070 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -598,11 +598,17 @@ struct skb_shared_info { * Warning : all fields before dataref are cleared in __alloc_skb() */ atomic_t dataref; - unsigned int xdp_frags_size; - /* Intermediate layers must ensure that destructor_arg - * remains valid until skb destructor */ - void * destructor_arg; + union { + struct { + unsigned int xdp_frags_size; + u32 xdp_frags_truesize; + }; + + /* Intermediate layers must ensure that destructor_arg + * remains valid until skb destructor */ + void * destructor_arg; + }; /* must be last field, see pskb_expand_head() */ skb_frag_t frags[MAX_SKB_FRAGS]; diff --git a/include/net/xdp.h b/include/net/xdp.h index 909c0bc50517..a3dc0f39b437 100644 --- a/include/net/xdp.h +++ b/include/net/xdp.h @@ -165,6 +165,34 @@ xdp_get_buff_len(const struct xdp_buff *xdp) return len; } +static inline bool xdp_buff_add_frag(struct xdp_buff *xdp, struct page *page, + u32 offset, u32 size, u32 truesize) +{ + struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); + + if (!xdp_buff_has_frags(xdp)) { + sinfo->nr_frags = 0; + + sinfo->xdp_frags_size = 0; + sinfo->xdp_frags_truesize = 0; + + xdp_buff_set_frags_flag(xdp); + } + + if (unlikely(sinfo->nr_frags == MAX_SKB_FRAGS)) + return false; + + __skb_fill_page_desc_noacc(sinfo, sinfo->nr_frags++, page, offset, + size); + sinfo->xdp_frags_size += size; + sinfo->xdp_frags_truesize += truesize; + + if (unlikely(page_is_pfmemalloc(page))) + xdp_buff_set_frag_pfmemalloc(xdp); + + return true; +} + struct xdp_frame { void *data; u16 len; @@ -230,7 +258,13 @@ xdp_update_skb_shared_info(struct sk_buff *skb, u8 nr_frags, unsigned int size, unsigned int truesize, bool pfmemalloc) { - skb_shinfo(skb)->nr_frags = nr_frags; + struct skb_shared_info *sinfo = skb_shinfo(skb); + + sinfo->nr_frags = nr_frags; + /* ``destructor_arg`` is unionized with ``xdp_frags_{,true}size``, + * reset it after that these fields aren't used anymore. + */ + sinfo->destructor_arg = NULL; skb->len += size; skb->data_len += size; -- 2.43.0 _______________________________________________ Intel-wired-lan mailing list [email protected] https://lists.osuosl.org/mailman/listinfo/intel-wired-lan
