[PATCH v15 02/17]Add a new struct for device to manipulate external buffer.

[xiaohui . xin]

From: Xin Xiaohui <xiaohui.xin@xxxxxxxxx>

    Add a structure in structure net_device, the new field is
    named as mp_port. It's for mediate passthru (zero-copy).
    It contains the capability for the net device driver,
    a socket, and an external buffer creator, external means
    skb buffer belongs to the device may not be allocated from
    kernel space.

    Signed-off-by: Xin Xiaohui <xiaohui.xin@xxxxxxxxx>
    Signed-off-by: Zhao Yu <yzhao81new@xxxxxxxxx>
    Reviewed-by: Jeff Dike <jdike@xxxxxxxxxxxxxxx>
---
 include/linux/netdevice.h |   25 ++++++++++++++++++++++++-
 1 files changed, 24 insertions(+), 1 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 46c36ff..f6b1870 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -325,6 +325,28 @@ enum netdev_state_t {
 	__LINK_STATE_DORMANT,
 };
 
+/*The structure for mediate passthru(zero-copy). */
+struct mp_port	{
+	/* the header len */
+	int		hdr_len;
+	/* the max payload len for one descriptor */
+	int		data_len;
+	/* the pages for DMA in one time */
+	int		npages;
+	/* the socket bind to */
+	struct socket	*sock;
+	/* the header len for virtio-net */
+	int		vnet_hlen;
+	/* the external buffer page creator */
+	struct skb_ext_page *(*ctor)(struct mp_port *,
+				struct sk_buff *, int);
+	/* the hash function attached to find according
+	 * backend ring descriptor info for one external
+	 * buffer page.
+	 */
+	struct skb_ext_page *(*hash)(struct net_device *,
+				struct page *);
+};
 
 /*
  * This structure holds at boot time configured netdevice settings. They
@@ -1045,7 +1067,8 @@ struct net_device {
 
 	/* GARP */
 	struct garp_port	*garp_port;
-
+	/* mpassthru */
+	struct mp_port		*mp_port;
 	/* class/net/name entry */
 	struct device		dev;
 	/* space for optional device, statistics, and wireless sysfs groups */
-- 
1.7.3

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