From 45a9e6d8a687e6a0ea6c2f78f15955ae96be4720 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 14 May 2020 12:49:48 +0200 Subject: [PATCH] veth: Xdp using frame_sz in veth driver MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The veth driver can run XDP in "native" mode in it's own NAPI handler, and since commit 9fc8d518d9d5 ("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: Jesper Dangaard Brouer Signed-off-by: Alexei Starovoitov Reviewed-by: Lorenzo Bianconi Acked-by: Toke Høiland-Jørgensen Acked-by: Toshiaki Makita Link: https://lore.kernel.org/bpf/158945338840.97035.935897116345700902.stgit@firesoul --- drivers/net/veth.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/net/veth.c b/drivers/net/veth.c index d5691bb..b586d2f 100644 --- a/drivers/net/veth.c +++ b/drivers/net/veth.c @@ -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; -- 2.7.4