Commit 539c1fba authored by Alexander Lobakin's avatar Alexander Lobakin Committed by Jakub Kicinski
Browse files

xdp: add generic xdp_build_skb_from_buff() 



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.

Reviewed-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAlexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20241218174435.1445282-4-aleksander.lobakin@intel.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 68ddc8ae

include/net/xdp.h

+1 −0
Original line number Diff line number Diff line
@@ -336,6 +336,7 @@ 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,

net/core/xdp.c

+55 −0
Original line number Diff line number Diff line
@@ -629,6 +629,61 @@ 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 &xdp_buff

 * @xdp: &xdp_buff to convert to an skb

 *

 * Perform common operations to create a new skb to pass up the stack from

 * &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;

	}



	skb = napi_build_skb(xdp->data_hard_start, xdp->frame_sz);

	if (unlikely(!skb))

		return NULL;



	skb_reserve(skb, xdp->data - xdp->data_hard_start);

	__skb_put(skb, xdp->data_end - xdp->data);



	metalen = xdp->data - xdp->data_meta;

	if (metalen > 0)

		skb_metadata_set(skb, metalen);



	if (rxq->mem.type == MEM_TYPE_PAGE_POOL)

		skb_mark_for_recycle(skb);



	skb_record_rx_queue(skb, rxq->queue_index);



	if (unlikely(nr_frags)) {

		u32 tsize;



		tsize = sinfo->xdp_frags_truesize ? : nr_frags * xdp->frame_sz;

		xdp_update_skb_shared_info(skb, nr_frags,

					   sinfo->xdp_frags_size, tsize,

					   xdp_buff_is_frag_pfmemalloc(xdp));

	}



	skb->protocol = eth_type_trans(skb, rxq->dev);



	return skb;

}

EXPORT_SYMBOL_GPL(xdp_build_skb_from_buff);



struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,

					   struct sk_buff *skb,

					   struct net_device *dev)