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. > > 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 > >> > >>
