On Thu, Jul 23, 2026 at 03:59:44PM +0800, Jason Xing wrote: > On Thu, Jul 23, 2026 at 3:02 PM Chenguang Zhao <[email protected]> > wrote: > > > > Thanks for the clarification. > > Please do not top-post. > > > > > I agree: the minimal bugfix belongs in -net for stable backportability, and > > the conversion to xdp_build_skb_from_zc() belongs in -next. > > Right. That's what I meant. But I will let Maciej/Tony/Olek make the decision.
Thanks Jason - agree with the logistics you are proposing. > > > > > Please apply the existing v1 bugfix to -net: > > > > > > https://lore.kernel.org/all/[email protected]/ > > If we eventually need this patch, then you will send a v3 patch > instead of asking maintainers to pick it up :) > > And feel free to add: > Reviewed-by: Jason Xing <[email protected]> > > > > > It already has : > > > > Reviewed-by: Aleksandr Loktionov <[email protected]> > > > > I will drop v2 as a Fixes candidate. > > > > In parallel, I will send a separate net-next series (as v1) that replaces > > > > i40e_construct_skb_zc() with xdp_build_skb_from_zc(), based on > > > > net-next. That patch will not carry a Fixes tag. > > As to this version, my tag still holds: > Reviewed-by: Jason Xing <[email protected]> > > Thanks, > Jason > > > > > > > Thanks, > > > > Chenguang > > > > > > 在 2026/7/22 07:15, Jason Xing 写道: > > > On Fri, Jul 17, 2026 at 9:24 AM Chenguang Zhao <[email protected]> > > > wrote: > > >> From: Chenguang Zhao <[email protected]> > > >> > > >> When AF_XDP ZC receives a multi-buffer frame and XDP returns XDP_PASS, > > >> i40e_construct_skb_zc() copied frags incorrectly: memcpy used > > >> skb_frag_page() (page metadata) and __skb_fill_page_desc_noacc() was > > >> given a virtual address instead of a struct page *. > > >> > > >> Drop the custom helper and use xdp_build_skb_from_zc() instead. On > > >> failure, free the xdp buff in the caller. Push the Ethernet header > > >> back before eth_skb_pad()/i40e_process_skb_fields() because > > >> xdp_build_skb_from_zc() already called eth_type_trans(). > > >> > > >> Fixes: 1c9ba9c14658 ("i40e: xsk: add RX multi-buffer support") > > >> Signed-off-by: Chenguang Zhao <[email protected]> > > >> --- > > >> Revised as suggested by Maciej: > > >> - Replace i40e_construct_skb_zc() with xdp_build_skb_from_zc() > > > I might have a different opinion on this patch: yes, it actually > > > belongs to -next material. The process should be like: 1) fix the > > > issues by v1, 2) refactor it by v2. The reason behind that is the > > > helper was introduced in 2024 while the home-grown part was in 2023, > > > which means it doesn't help for stable steam to cherry-pick the patch > > > in older kernels like 6.6[1]. > > > > > > [1]: https://www.kernel.org/ > > > > > > Thanks, > > > Jason > > > > > >> v1: > > >> > > >> https://lore.kernel.org/all/[email protected]/ > > >> > > >> drivers/net/ethernet/intel/i40e/i40e_xsk.c | 73 +++------------------- > > >> 1 file changed, 8 insertions(+), 65 deletions(-) > > >> > > >> diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c > > >> b/drivers/net/ethernet/intel/i40e/i40e_xsk.c > > >> index 9f47388eaba5..1319a5c22625 100644 > > >> --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c > > >> +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c > > >> @@ -3,6 +3,7 @@ > > >> > > >> #include <linux/bpf_trace.h> > > >> #include <linux/unroll.h> > > >> +#include <net/xdp.h> > > >> #include <net/xdp_sock_drv.h> > > >> #include "i40e_txrx_common.h" > > >> #include "i40e_xsk.h" > > >> @@ -277,70 +278,6 @@ bool i40e_alloc_rx_buffers_zc(struct i40e_ring > > >> *rx_ring, u16 count) > > >> return count == nb_buffs; > > >> } > > >> > > >> -/** > > >> - * i40e_construct_skb_zc - Create skbuff from zero-copy Rx buffer > > >> - * @rx_ring: Rx ring > > >> - * @xdp: xdp_buff > > >> - * > > >> - * This functions allocates a new skb from a zero-copy Rx buffer. > > >> - * > > >> - * Returns the skb, or NULL on failure. > > >> - **/ > > >> -static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring, > > >> - struct xdp_buff *xdp) > > >> -{ > > >> - unsigned int totalsize = xdp->data_end - xdp->data_meta; > > >> - unsigned int metasize = xdp->data - xdp->data_meta; > > >> - struct skb_shared_info *sinfo = NULL; > > >> - struct sk_buff *skb; > > >> - u32 nr_frags = 0; > > >> - > > >> - if (unlikely(xdp_buff_has_frags(xdp))) { > > >> - sinfo = xdp_get_shared_info_from_buff(xdp); > > >> - nr_frags = sinfo->nr_frags; > > >> - } > > >> - net_prefetch(xdp->data_meta); > > >> - > > >> - /* allocate a skb to store the frags */ > > >> - skb = napi_alloc_skb(&rx_ring->q_vector->napi, totalsize); > > >> - if (unlikely(!skb)) > > >> - goto out; > > >> - > > >> - memcpy(__skb_put(skb, totalsize), xdp->data_meta, > > >> - ALIGN(totalsize, sizeof(long))); > > >> - > > >> - if (metasize) { > > >> - skb_metadata_set(skb, metasize); > > >> - __skb_pull(skb, metasize); > > >> - } > > >> - > > >> - if (likely(!xdp_buff_has_frags(xdp))) > > >> - goto out; > > >> - > > >> - for (int i = 0; i < nr_frags; i++) { > > >> - struct skb_shared_info *skinfo = skb_shinfo(skb); > > >> - skb_frag_t *frag = &sinfo->frags[i]; > > >> - struct page *page; > > >> - void *addr; > > >> - > > >> - page = dev_alloc_page(); > > >> - if (!page) { > > >> - dev_kfree_skb(skb); > > >> - return NULL; > > >> - } > > >> - addr = page_to_virt(page); > > >> - > > >> - memcpy(addr, skb_frag_page(frag), skb_frag_size(frag)); > > >> - > > >> - __skb_fill_page_desc_noacc(skinfo, skinfo->nr_frags++, > > >> - addr, 0, skb_frag_size(frag)); > > >> - } > > >> - > > >> -out: > > >> - xsk_buff_free(xdp); > > >> - return skb; > > >> -} > > >> - > > >> static void i40e_handle_xdp_result_zc(struct i40e_ring *rx_ring, > > >> struct xdp_buff *xdp_buff, > > >> union i40e_rx_desc *rx_desc, > > >> @@ -372,14 +309,20 @@ static void i40e_handle_xdp_result_zc(struct > > >> i40e_ring *rx_ring, > > >> * BIT(I40E_RXD_QW1_ERROR_SHIFT). This is due to that > > >> * SBP is *not* set in PRT_SBPVSI (default not set). > > >> */ > > >> - skb = i40e_construct_skb_zc(rx_ring, xdp_buff); > > >> + skb = xdp_build_skb_from_zc(xdp_buff); > > >> if (!skb) { > > >> + xsk_buff_free(xdp_buff); > > >> rx_ring->rx_stats.alloc_buff_failed++; > > >> *rx_packets = 0; > > >> *rx_bytes = 0; > > >> return; > > >> } > > >> > > >> + /* xdp_build_skb_from_zc() already ran eth_type_trans(); > > >> + * restore the header for > > >> eth_skb_pad()/process_skb_fields(). > > >> + */ > > >> + __skb_push(skb, skb->data - skb_mac_header(skb)); > > >> + > > >> if (eth_skb_pad(skb)) { > > >> *rx_packets = 0; > > >> *rx_bytes = 0; > > >> -- > > >> 2.25.1 > > >> > > >> >
