Merge branch 'hv_netvsc-less-headroom'

Merge branch 'hv_netvsc-less-headroom'

K. Y. Srinivasan says:

====================
hv_netvsc: Eliminate the additional head room

In an attempt to avoid having to allocate memory on the send path, the netvsc
driver was requesting additional head room so that both rndis header and the
netvsc packet (the state that had to persist) could be placed in the skb.
Since the amount of head room requested was exceeding the default head room
as set in LL_MAX_HEADER, we were forcing a reallocation of skb.

With this patch-set, I have reduced the size of the netvsc packet to less
than 20 bytes and with this reduction we don't need to ask for any additional
headroom. We place the rndis header in the skb head room and we place the
netvsc packet in control buffer area in the skb.

V2:  - Addressed  review comments:
     - Eliminated more fields from netvsc packet structure.

V3:  - Fixed a typo in patch: hv_netvsc: Don't ask for additional head room in the skb.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/hyperv_net.h

@@ -124,37 +124,22 @@ struct ndis_tcp_ip_checksum_info;
 /*
  * Represent netvsc packet which contains 1 RNDIS and 1 ethernet frame
  * within the RNDIS
+ *
+ * The size of this structure is less than 48 bytes and we can now
+ * place this structure in the skb->cb field.
  */
 struct hv_netvsc_packet {
 	/* Bookkeeping stuff */
-	u32 status;
-
-	bool is_data_pkt;
-	bool xmit_more; /* from skb */
-	bool cp_partial; /* partial copy into send buffer */
+	u8 cp_partial; /* partial copy into send buffer */
 
-	u16 vlan_tci;
+	u8 rmsg_size; /* RNDIS header and PPI size */
+	u8 rmsg_pgcnt; /* page count of RNDIS header and PPI */
+	u8 page_buf_cnt;
 
 	u16 q_idx;
-	struct vmbus_channel *channel;
-
-	u64 send_completion_tid;
-	void *send_completion_ctx;
-	void (*send_completion)(void *context);
-
 	u32 send_buf_index;
 
-	/* This points to the memory after page_buf */
-	struct rndis_message *rndis_msg;
-
-	u32 rmsg_size; /* RNDIS header and PPI size */
-	u32 rmsg_pgcnt; /* page count of RNDIS header and PPI */
-
 	u32 total_data_buflen;
-	/* Points to the send/receive buffer where the ethernet frame is */
-	void *data;
-	u32 page_buf_cnt;
-	struct hv_page_buffer *page_buf;
 };
 
 struct netvsc_device_info {
@@ -187,29 +172,36 @@ struct rndis_device {
 
 
 /* Interface */
+struct rndis_message;
 int netvsc_device_add(struct hv_device *device, void *additional_info);
 int netvsc_device_remove(struct hv_device *device);
 int netvsc_send(struct hv_device *device,
-		struct hv_netvsc_packet *packet);
+		struct hv_netvsc_packet *packet,
+		struct rndis_message *rndis_msg,
+		struct hv_page_buffer **page_buffer,
+		struct sk_buff *skb);
 void netvsc_linkstatus_callback(struct hv_device *device_obj,
 				struct rndis_message *resp);
-void netvsc_xmit_completion(void *context);
 int netvsc_recv_callback(struct hv_device *device_obj,
 			struct hv_netvsc_packet *packet,
-			struct ndis_tcp_ip_checksum_info *csum_info);
+			void **data,
+			struct ndis_tcp_ip_checksum_info *csum_info,
+			struct vmbus_channel *channel,
+			u16 vlan_tci);
 void netvsc_channel_cb(void *context);
 int rndis_filter_open(struct hv_device *dev);
 int rndis_filter_close(struct hv_device *dev);
 int rndis_filter_device_add(struct hv_device *dev,
 			void *additional_info);
 void rndis_filter_device_remove(struct hv_device *dev);
 int rndis_filter_receive(struct hv_device *dev,
-			struct hv_netvsc_packet *pkt);
+			struct hv_netvsc_packet *pkt,
+			void **data,
+			struct vmbus_channel *channel);
 
 int rndis_filter_set_packet_filter(struct rndis_device *dev, u32 new_filter);
 int rndis_filter_set_device_mac(struct hv_device *hdev, char *mac);
 
-
 #define NVSP_INVALID_PROTOCOL_VERSION	((u32)0xFFFFFFFF)
 
 #define NVSP_PROTOCOL_VERSION_1		2
@@ -632,7 +624,6 @@ struct nvsp_message {
 #define RNDIS_PKT_ALIGN_DEFAULT 8
 
 struct multi_send_data {
-	spinlock_t lock; /* protect struct multi_send_data */
 	struct hv_netvsc_packet *pkt; /* netvsc pkt pending */
 	u32 count; /* counter of batched packets */
 };
@@ -1272,5 +1263,4 @@ struct rndis_message {
 #define TRANSPORT_INFO_IPV6_TCP ((INFO_IPV6 << 16) | INFO_TCP)
 #define TRANSPORT_INFO_IPV6_UDP ((INFO_IPV6 << 16) | INFO_UDP)
 
-
 #endif /* _HYPERV_NET_H */