On 12.02.24 11:50, Lorenzo Bianconi wrote:
> Similar to native xdp, do not always linearize the skb in
> netif_receive_generic_xdp routine but create a non-linear xdp_buff to be
> processed by the eBPF program. This allow to add multi-buffer support
> for xdp running in generic mode.
>
> Acked-by: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
> Reviewed-by: Toke Hoiland-Jorgensen <toke@xxxxxxxxxx>
> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> ---
> include/linux/skbuff.h | 2 +
> net/core/dev.c | 70 +++++++++++++++++++++++---------
> net/core/skbuff.c | 91 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 144 insertions(+), 19 deletions(-)
>
[...]
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 9e5eb47b4025..bdb94749f05d 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -895,6 +895,97 @@ static bool is_pp_page(struct page *page)
> return (page->pp_magic & ~0x3UL) == PP_SIGNATURE;
> }
>
> +static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
> + unsigned int headroom)
> +{
> +#if IS_ENABLED(CONFIG_PAGE_POOL)
> + u32 size, truesize, len, max_head_size, off;
> + struct sk_buff *skb = *pskb, *nskb;
> + int err, i, head_off;
> + void *data;
> +
> + /* XDP does not support fraglist so we need to linearize
> + * the skb.
> + */
> + if (skb_has_frag_list(skb))
> + return -EOPNOTSUPP;
> +
> + max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - headroom);
> + if (skb->len > max_head_size + MAX_SKB_FRAGS * PAGE_SIZE)
> + return -ENOMEM;
> +
> + size = min_t(u32, skb->len, max_head_size);
> + truesize = SKB_HEAD_ALIGN(size) + headroom;
> + data = page_pool_dev_alloc_va(pool, &truesize);
> + if (!data)
> + return -ENOMEM;
> +
> + nskb = napi_build_skb(data, truesize);
> + if (!nskb) {
> + page_pool_free_va(pool, data, true);
> + return -ENOMEM;
> + }
> +
> + skb_reserve(nskb, headroom);
> + skb_copy_header(nskb, skb);
> + skb_mark_for_recycle(nskb);
> +
> + err = skb_copy_bits(skb, 0, nskb->data, size);
> + if (err) {
> + consume_skb(nskb);
> + return err;
> + }
> + skb_put(nskb, size);
> +
> + head_off = skb_headroom(nskb) - skb_headroom(skb);
> + skb_headers_offset_update(nskb, head_off);
> +
> + off = size;
> + len = skb->len - off;
> + for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
> + struct page *page;
> + u32 page_off;
> +
> + size = min_t(u32, len, PAGE_SIZE);
> + truesize = size;
> +
> + page = page_pool_dev_alloc(pool, &page_off, &truesize);
> + if (!data) {
> + consume_skb(nskb);
> + return -ENOMEM;
> + }
> +
This should check for !page instead, no?
(picked up as CID 1583654 by the coverity scan for linux-next)
