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From: Jesper Dangaard Brouer <brouer@redhat.com>
To: sameehj@amazon.com
Cc: "Jesper Dangaard Brouer" <brouer@redhat.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	"Toke Høiland-Jørgensen" <toke@redhat.com>,
	"Daniel Borkmann" <borkmann@iogearbox.net>,
	"Alexei Starovoitov" <alexei.starovoitov@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Alexander Duyck" <alexander.duyck@gmail.com>,
	"Jeff Kirsher" <jeffrey.t.kirsher@intel.com>,
	"David Ahern" <dsahern@gmail.com>,
	"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
	"Lorenzo Bianconi" <lorenzo@kernel.org>,
	"Saeed Mahameed" <saeedm@mellanox.com>,
	"Tariq Toukan" <tariqt@mellanox.com>
Subject: [PATCH net-next v4 06/33] net: XDP-generic determining XDP frame size
Date: Thu, 14 May 2020 12:49:28 +0200	[thread overview]
Message-ID: <158945336804.97035.7164852191163722056.stgit@firesoul> (raw)
In-Reply-To: <158945314698.97035.5286827951225578467.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 4c91de39890a..f937a3ff668d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4617,6 +4617,11 @@ 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;
@@ -4640,14 +4645,11 @@ 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	other threads:[~2020-05-14 10:49 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14 10:48 [PATCH net-next v4 00/33] XDP extend with knowledge of " Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 01/33] xdp: add frame size to xdp_buff Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 02/33] bnxt: add XDP frame size to driver Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 03/33] sfc: add XDP frame size Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 04/33] mvneta: add XDP frame size to driver Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 05/33] net: netsec: Add support for XDP frame size Jesper Dangaard Brouer
2020-05-14 10:49 ` Jesper Dangaard Brouer [this message]
2020-05-14 10:49 ` [PATCH net-next v4 07/33] xdp: xdp_frame add member frame_sz and handle in convert_to_xdp_frame Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 08/33] xdp: cpumap redirect use frame_sz and increase skb_tailroom Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 09/33] veth: adjust hard_start offset on redirect XDP frames Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 10/33] veth: xdp using frame_sz in veth driver Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 11/33] dpaa2-eth: add XDP frame size Jesper Dangaard Brouer
2020-05-14 10:49 ` [PATCH net-next v4 12/33] hv_netvsc: add XDP frame size to driver Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 13/33] qlogic/qede: " Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 14/33] net: ethernet: ti: add XDP frame size to driver cpsw Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 15/33] ena: add XDP frame size to amazon NIC driver Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 16/33] mlx4: add XDP frame size and adjust max XDP MTU Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 17/33] net: thunderx: add XDP frame size Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 18/33] nfp: add XDP frame size to netronome driver Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 19/33] tun: add XDP frame size Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 20/33] vhost_net: also populate " Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 21/33] virtio_net: add XDP frame size in two code paths Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 22/33] ixgbe: fix XDP redirect on archs with PAGE_SIZE above 4K Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 23/33] ixgbe: add XDP frame size to driver Jesper Dangaard Brouer
2020-05-14 10:50 ` [PATCH net-next v4 24/33] ixgbevf: add XDP frame size to VF driver Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 25/33] i40e: add XDP frame size to driver Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 26/33] ice: " Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 27/33] xdp: for Intel AF_XDP drivers add XDP frame_sz Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 28/33] mlx5: rx queue setup time determine frame_sz for XDP Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 29/33] xdp: allow bpf_xdp_adjust_tail() to grow packet size Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 30/33] xdp: clear grow memory in bpf_xdp_adjust_tail() Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 31/33] bpf: add xdp.frame_sz in bpf_prog_test_run_xdp() Jesper Dangaard Brouer
2020-05-17  4:02   ` unstable xdp tests. Was: " Alexei Starovoitov
2020-05-18  9:52     ` Jesper Dangaard Brouer
2020-05-18 10:30       ` Jesper Dangaard Brouer
2020-05-18 19:19         ` Andrii Nakryiko
2020-05-14 10:51 ` [PATCH net-next v4 32/33] selftests/bpf: adjust BPF selftest for xdp_adjust_tail Jesper Dangaard Brouer
2020-05-14 10:51 ` [PATCH net-next v4 33/33] selftests/bpf: xdp_adjust_tail add grow tail tests Jesper Dangaard Brouer
2020-05-15  4:52 ` [PATCH net-next v4 00/33] XDP extend with knowledge of frame size Alexei Starovoitov

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