Commit 45a9e6d8 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by Alexei Starovoitov
Browse files

veth: Xdp using frame_sz in veth driver 



The veth driver can run XDP in "native" mode in it's own NAPI
handler, and since commit 9fc8d518 ("veth: Handle xdp_frames in
xdp napi ring") packets can come in two forms either xdp_frame or
skb, calling respectively veth_xdp_rcv_one() or veth_xdp_rcv_skb().

For packets to arrive in xdp_frame format, they will have been
redirected from an XDP native driver. In case of XDP_PASS or no
XDP-prog attached, the veth driver will allocate and create an SKB.

The current code in veth_xdp_rcv_one() xdp_frame case, had to guess
the frame truesize of the incoming xdp_frame, when using
veth_build_skb(). With xdp_frame->frame_sz this is not longer
necessary.

Calculating the frame_sz in veth_xdp_rcv_skb() skb case, is done
similar to the XDP-generic handling code in net/core/dev.c.

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Reviewed-by: default avatarLorenzo Bianconi <lorenzo@kernel.org>
Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: default avatarToshiaki Makita <toshiaki.makita1@gmail.com>
Link: https://lore.kernel.org/bpf/158945338840.97035.935897116345700902.stgit@firesoul
parent 5c857225

drivers/net/veth.c

+13 −9
Original line number Diff line number Diff line
@@ -405,10 +405,6 @@ static struct sk_buff *veth_build_skb(void *head, int headroom, int len, 
{

	struct sk_buff *skb;



	if (!buflen) {

		buflen = SKB_DATA_ALIGN(headroom + len) +

			 SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

	}

	skb = build_skb(head, buflen);

	if (!skb)

		return NULL;
@@ -583,6 +579,7 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq, 
		xdp.data = frame->data;

		xdp.data_end = frame->data + frame->len;

		xdp.data_meta = frame->data - frame->metasize;

		xdp.frame_sz = frame->frame_sz;

		xdp.rxq = &rq->xdp_rxq;



		act = bpf_prog_run_xdp(xdp_prog, &xdp);
@@ -629,7 +626,7 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq, 
	rcu_read_unlock();



	headroom = sizeof(struct xdp_frame) + frame->headroom - delta;

	skb = veth_build_skb(hard_start, headroom, len, 0);

	skb = veth_build_skb(hard_start, headroom, len, frame->frame_sz);

	if (!skb) {

		xdp_return_frame(frame);

		stats->rx_drops++;
@@ -695,9 +692,8 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq, 
			goto drop;

		}



		nskb = veth_build_skb(head,

				      VETH_XDP_HEADROOM + mac_len, skb->len,

				      PAGE_SIZE);

		nskb = veth_build_skb(head, VETH_XDP_HEADROOM + mac_len,

				      skb->len, PAGE_SIZE);

		if (!nskb) {

			page_frag_free(head);

			goto drop;
@@ -715,6 +711,11 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq, 
	xdp.data_end = xdp.data + pktlen;

	xdp.data_meta = xdp.data;

	xdp.rxq = &rq->xdp_rxq;



	/* SKB "head" area always have tailroom for skb_shared_info */

	xdp.frame_sz = (void *)skb_end_pointer(skb) - xdp.data_hard_start;

	xdp.frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));



	orig_data = xdp.data;

	orig_data_end = xdp.data_end;
@@ -758,6 +759,7 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq, 
	}

	rcu_read_unlock();



	/* check if bpf_xdp_adjust_head was used */

	delta = orig_data - xdp.data;

	off = mac_len + delta;

	if (off > 0)
@@ -765,9 +767,11 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq, 
	else if (off < 0)

		__skb_pull(skb, -off);

	skb->mac_header -= delta;



	/* check if bpf_xdp_adjust_tail was used */

	off = xdp.data_end - orig_data_end;

	if (off != 0)

		__skb_put(skb, off);

		__skb_put(skb, off); /* positive on grow, negative on shrink */

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



	metalen = xdp.data - xdp.data_meta;

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