netdev - [bpf-next V1 PATCH 05/15] xdp: introduce a new xdp

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Message-ID: <152037289047.25478.9430972413018479237.stgit@firesoul>
Date:   Tue, 06 Mar 2018 22:48:10 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     netdev@...r.kernel.org,
        BjörnTöpel <bjorn.topel@...el.com>,
        magnus.karlsson@...el.com
Cc:     eugenia@...lanox.com, Jason Wang <jasowang@...hat.com>,
        John Fastabend <john.fastabend@...il.com>,
        Eran Ben Elisha <eranbe@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>, galp@...lanox.com,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>
Subject: [bpf-next V1 PATCH 05/15] xdp: introduce a new xdp_frame type

This is needed to convert drivers tuntap and virtio_net.

This is a generalization of what is done inside cpumap, which will be
converted later.

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
 include/net/xdp.h |   40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index f6cbbbad412f..c5e7e2d27dd8 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -63,6 +63,46 @@ struct xdp_buff {
 	struct xdp_rxq_info *rxq;
 };
 
+struct xdp_frame {
+	void *data;
+	u16 len;
+	u16 headroom;
+	u16 metasize;
+	/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
+	 * while mem info is valid on remote CPU.
+	 */
+	struct xdp_mem_info mem;
+};
+
+/* Convert xdp_buff to xdp_frame */
+static inline
+struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
+{
+	struct xdp_frame *xdp_frame;
+	int metasize;
+	int headroom;
+
+	/* Assure headroom is available for storing info */
+	headroom = xdp->data - xdp->data_hard_start;
+	metasize = xdp->data - xdp->data_meta;
+	metasize = metasize > 0 ? metasize : 0;
+	if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
+		return NULL;
+
+	/* Store info in top of packet */
+	xdp_frame = xdp->data_hard_start;
+
+	xdp_frame->data = xdp->data;
+	xdp_frame->len  = xdp->data_end - xdp->data;
+	xdp_frame->headroom = headroom - sizeof(*xdp_frame);
+	xdp_frame->metasize = metasize;
+
+	/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
+	xdp_frame->mem = xdp->rxq->mem;
+
+	return xdp_frame;
+}
+
 static inline
 void xdp_return_frame(void *data, struct xdp_mem_info *mem)
 {