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From: Jesper Dangaard Brouer <brouer@redhat.com>
To: sameehj@amazon.com
Cc: "Toke Høiland-Jørgensen" <toke@redhat.com>,
	"Jesper Dangaard Brouer" <brouer@redhat.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org, zorik@amazon.com,
	akiyano@amazon.com, gtzalik@amazon.com,
	"Toke Høiland-Jørgensen" <toke@redhat.com>,
	"Daniel Borkmann" <borkmann@iogearbox.net>,
	"Alexei Starovoitov" <alexei.starovoitov@gmail.com>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Alexander Duyck" <alexander.duyck@gmail.com>,
	"Jeff Kirsher" <jeffrey.t.kirsher@intel.com>,
	"David Ahern" <dsahern@gmail.com>,
	"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
	"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
	"Lorenzo Bianconi" <lorenzo@kernel.org>,
	"Saeed Mahameed" <saeedm@mellanox.com>,
	steffen.klassert@secunet.com
Subject: [PATCH net-next v2 06/33] net: XDP-generic determining XDP frame size
Date: Thu, 30 Apr 2020 13:20:51 +0200
Message-ID: <158824565189.2172139.15984289372325616869.stgit@firesoul> (raw)
In-Reply-To: <158824557985.2172139.4173570969543904434.stgit@firesoul>

The SKB "head" pointer points to the data area that contains
skb_shared_info, that can be found via skb_end_pointer(). Given
xdp->data_hard_start have been established (basically pointing to
skb->head), frame size is between skb_end_pointer() and data_hard_start,
plus the size reserved to skb_shared_info.

Change the bpf_xdp_adjust_tail offset adjust of skb->len, to be a positive
offset number on grow, and negative number on shrink.  As this seems more
natural when reading the code.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 net/core/dev.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index afff16849c26..b364e6f3a37a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4549,6 +4549,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
 	xdp->data_meta = xdp->data;
 	xdp->data_end = xdp->data + hlen;
 	xdp->data_hard_start = skb->data - skb_headroom(skb);
+
+	/* 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_end = xdp->data_end;
 	orig_data = xdp->data;
 	eth = (struct ethhdr *)xdp->data;
@@ -4572,14 +4577,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
 		skb_reset_network_header(skb);
 	}
 
-	/* check if bpf_xdp_adjust_tail was used. it can only "shrink"
-	 * pckt.
-	 */
-	off = orig_data_end - xdp->data_end;
+	/* check if bpf_xdp_adjust_tail was used */
+	off = xdp->data_end - orig_data_end;
 	if (off != 0) {
 		skb_set_tail_pointer(skb, xdp->data_end - xdp->data);
-		skb->len -= off;
-
+		skb->len += off; /* positive on grow, negative on shrink */
 	}
 
 	/* check if XDP changed eth hdr such SKB needs update */



  parent reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <158824557985.2172139.4173570969543904434.stgit@firesoul>
2020-04-30 11:20 ` [PATCH net-next v2 01/33] xdp: add frame size to xdp_buff Jesper Dangaard Brouer
2020-04-30 11:20 ` [PATCH net-next v2 02/33] bnxt: add XDP frame size to driver Jesper Dangaard Brouer
2020-04-30 11:20 ` [PATCH net-next v2 03/33] sfc: add XDP frame size Jesper Dangaard Brouer
2020-04-30 11:20 ` [PATCH net-next v2 04/33] mvneta: add XDP frame size to driver Jesper Dangaard Brouer
2020-04-30 11:20 ` [PATCH net-next v2 05/33] net: netsec: Add support for XDP frame size Jesper Dangaard Brouer
2020-04-30 11:20 ` Jesper Dangaard Brouer [this message]
2020-04-30 11:20 ` [PATCH net-next v2 07/33] xdp: xdp_frame add member frame_sz and handle in convert_to_xdp_frame Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 08/33] xdp: cpumap redirect use frame_sz and increase skb_tailroom Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 09/33] veth: adjust hard_start offset on redirect XDP frames Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 10/33] veth: xdp using frame_sz in veth driver Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 11/33] dpaa2-eth: add XDP frame size Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 12/33] hv_netvsc: add XDP frame size to driver Jesper Dangaard Brouer
2020-04-30 14:20   ` Haiyang Zhang
2020-05-01 14:47     ` Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 13/33] qlogic/qede: " Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 14/33] net: ethernet: ti: add XDP frame size to driver cpsw Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 15/33] ena: add XDP frame size to amazon NIC driver Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 16/33] mlx4: add XDP frame size and adjust max XDP MTU Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 17/33] net: thunderx: add XDP frame size Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 18/33] nfp: add XDP frame size to netronome driver Jesper Dangaard Brouer
2020-04-30 11:21 ` [PATCH net-next v2 19/33] tun: add XDP frame size Jesper Dangaard Brouer
2020-05-06 20:32   ` Michael S. Tsirkin
2020-04-30 11:22 ` [PATCH net-next v2 20/33] vhost_net: also populate " Jesper Dangaard Brouer
2020-05-06  6:41   ` Jason Wang
2020-05-06  6:49     ` Jason Wang
2020-05-06 20:33   ` Michael S. Tsirkin
2020-04-30 11:22 ` [PATCH net-next v2 21/33] virtio_net: add XDP frame size in two code paths Jesper Dangaard Brouer
2020-05-06 20:34   ` Michael S. Tsirkin
2020-05-08  2:05     ` Jason Wang
2020-05-08  7:21       ` Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 22/33] ixgbe: fix XDP redirect on archs with PAGE_SIZE above 4K Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 23/33] ixgbe: add XDP frame size to driver Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 24/33] ixgbevf: add XDP frame size to VF driver Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 25/33] i40e: add XDP frame size to driver Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 26/33] ice: " Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 27/33] xdp: for Intel AF_XDP drivers add XDP frame_sz Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 28/33] mlx5: rx queue setup time determine frame_sz for XDP Jesper Dangaard Brouer
2020-04-30 17:07   ` Tariq Toukan
2020-04-30 17:12     ` Tariq Toukan
2020-05-01 12:32       ` Jesper Dangaard Brouer
2020-05-08 10:49         ` Jesper Dangaard Brouer
2020-05-01 13:01     ` Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 29/33] xdp: allow bpf_xdp_adjust_tail() to grow packet size Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 30/33] xdp: clear grow memory in bpf_xdp_adjust_tail() Jesper Dangaard Brouer
2020-04-30 11:22 ` [PATCH net-next v2 31/33] bpf: add xdp.frame_sz in bpf_prog_test_run_xdp() Jesper Dangaard Brouer
2020-04-30 11:23 ` [PATCH net-next v2 32/33] selftests/bpf: adjust BPF selftest for xdp_adjust_tail Jesper Dangaard Brouer
2020-04-30 11:23 ` [PATCH net-next v2 33/33] selftests/bpf: xdp_adjust_tail add grow tail tests Jesper Dangaard Brouer

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