Alexander Lobakin <aleksander.lobakin@xxxxxxxxx> writes:
> The code which builds an skb from an &xdp_buff keeps multiplying itself
> around the drivers with almost no changes. Let's try to stop that by
> adding a generic function.
> Unlike __xdp_build_skb_from_frame(), always allocate an skbuff head
> using napi_build_skb() and make use of the available xdp_rxq pointer to
> assign the Rx queue index. In case of PP-backed buffer, mark the skb to
> be recycled, as every PP user's been switched to recycle skbs.
>
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
> ---
> include/net/xdp.h | 1 +
> net/core/xdp.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 56 insertions(+)
>
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index 4c19042adf80..b0a25b7060ff 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -330,6 +330,7 @@ xdp_update_skb_shared_info(struct sk_buff *skb, u8 nr_frags,
> void xdp_warn(const char *msg, const char *func, const int line);
> #define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
>
> +struct sk_buff *xdp_build_skb_from_buff(const struct xdp_buff *xdp);
> struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
> struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
> struct sk_buff *skb,
> diff --git a/net/core/xdp.c b/net/core/xdp.c
> index b1b426a9b146..3a9a3c14b080 100644
> --- a/net/core/xdp.c
> +++ b/net/core/xdp.c
> @@ -624,6 +624,61 @@ int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
> }
> EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);
>
> +/**
> + * xdp_build_skb_from_buff - create an skb from an &xdp_buff
> + * @xdp: &xdp_buff to convert to an skb
> + *
> + * Perform common operations to create a new skb to pass up the stack from
> + * an &xdp_buff: allocate an skb head from the NAPI percpu cache, initialize
> + * skb data pointers and offsets, set the recycle bit if the buff is PP-backed,
> + * Rx queue index, protocol and update frags info.
> + *
> + * Return: new &sk_buff on success, %NULL on error.
> + */
> +struct sk_buff *xdp_build_skb_from_buff(const struct xdp_buff *xdp)
> +{
> + const struct xdp_rxq_info *rxq = xdp->rxq;
> + const struct skb_shared_info *sinfo;
> + struct sk_buff *skb;
> + u32 nr_frags = 0;
> + int metalen;
> +
> + if (unlikely(xdp_buff_has_frags(xdp))) {
> + sinfo = xdp_get_shared_info_from_buff(xdp);
> + nr_frags = sinfo->nr_frags;
> + }
Why this separate branch at the start of the function? nr_frags is no
used until the other branch below, so why not just make that branch on
xdp_buff_has_frags() and keep everything frags-related together in one
block?
-Toke
