net/hyperv: Remove unnecessary kmap_atomic in netvsc driver

__get_free_pages() doesn't return HI memory, so the memory is always mapped.
kmap_atomic() is not necessary here. This patch removes the kmap_atomic()
calls and related code for locking and page manipulation.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/net/hyperv/hyperv_net.h

@@ -39,9 +39,6 @@ struct xferpage_packet {
 	u32 count;
 };
 
-/* The number of pages which are enough to cover jumbo frame buffer. */
-#define NETVSC_PACKET_MAXPAGE		4
-
 /*
  * Represent netvsc packet which contains 1 RNDIS and 1 ethernet frame
  * within the RNDIS
@@ -77,8 +74,9 @@ struct hv_netvsc_packet {
 
 	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[NETVSC_PACKET_MAXPAGE];
+	struct hv_page_buffer page_buf[0];
 };
 
 struct netvsc_device_info {

drivers/net/hyperv/netvsc.c

@@ -603,12 +603,10 @@ static void netvsc_receive(struct hv_device *device,
 	struct vmtransfer_page_packet_header *vmxferpage_packet;
 	struct nvsp_message *nvsp_packet;
 	struct hv_netvsc_packet *netvsc_packet = NULL;
-	unsigned long start;
-	unsigned long end, end_virtual;
 	/* struct netvsc_driver *netvscDriver; */
 	struct xferpage_packet *xferpage_packet = NULL;
-	int i, j;
-	int count = 0, bytes_remain = 0;
+	int i;
+	int count = 0;
 	unsigned long flags;
 	struct net_device *ndev;
 
@@ -717,53 +715,10 @@ static void netvsc_receive(struct hv_device *device,
 		netvsc_packet->completion.recv.recv_completion_tid =
 					vmxferpage_packet->d.trans_id;
 
+		netvsc_packet->data = (void *)((unsigned long)net_device->
+			recv_buf + vmxferpage_packet->ranges[i].byte_offset);
 		netvsc_packet->total_data_buflen =
 					vmxferpage_packet->ranges[i].byte_count;
-		netvsc_packet->page_buf_cnt = 1;
-
-		netvsc_packet->page_buf[0].len =
-					vmxferpage_packet->ranges[i].byte_count;
-
-		start = virt_to_phys((void *)((unsigned long)net_device->
-		recv_buf + vmxferpage_packet->ranges[i].byte_offset));
-
-		netvsc_packet->page_buf[0].pfn = start >> PAGE_SHIFT;
-		end_virtual = (unsigned long)net_device->recv_buf
-		    + vmxferpage_packet->ranges[i].byte_offset
-		    + vmxferpage_packet->ranges[i].byte_count - 1;
-		end = virt_to_phys((void *)end_virtual);
-
-		/* Calculate the page relative offset */
-		netvsc_packet->page_buf[0].offset =
-			vmxferpage_packet->ranges[i].byte_offset &
-			(PAGE_SIZE - 1);
-		if ((end >> PAGE_SHIFT) != (start >> PAGE_SHIFT)) {
-			/* Handle frame across multiple pages: */
-			netvsc_packet->page_buf[0].len =
-				(netvsc_packet->page_buf[0].pfn <<
-				 PAGE_SHIFT)
-				+ PAGE_SIZE - start;
-			bytes_remain = netvsc_packet->total_data_buflen -
-					netvsc_packet->page_buf[0].len;
-			for (j = 1; j < NETVSC_PACKET_MAXPAGE; j++) {
-				netvsc_packet->page_buf[j].offset = 0;
-				if (bytes_remain <= PAGE_SIZE) {
-					netvsc_packet->page_buf[j].len =
-						bytes_remain;
-					bytes_remain = 0;
-				} else {
-					netvsc_packet->page_buf[j].len =
-						PAGE_SIZE;
-					bytes_remain -= PAGE_SIZE;
-				}
-				netvsc_packet->page_buf[j].pfn =
-				    virt_to_phys((void *)(end_virtual -
-						bytes_remain)) >> PAGE_SHIFT;
-				netvsc_packet->page_buf_cnt++;
-				if (bytes_remain == 0)
-					break;
-			}
-		}
 
 		/* Pass it to the upper layer */
 		rndis_filter_receive(device, netvsc_packet);

drivers/net/hyperv/netvsc_drv.c

@@ -251,9 +251,6 @@ int netvsc_recv_callback(struct hv_device *device_obj,
 {
 	struct net_device *net = dev_get_drvdata(&device_obj->device);
 	struct sk_buff *skb;
-	void *data;
-	int i;
-	unsigned long flags;
 	struct netvsc_device *net_device;
 
 	net_device = hv_get_drvdata(device_obj);
@@ -272,27 +269,12 @@ int netvsc_recv_callback(struct hv_device *device_obj,
 		return 0;
 	}
 
-	/* for kmap_atomic */
-	local_irq_save(flags);
-
 	/*
 	 * Copy to skb. This copy is needed here since the memory pointed by
 	 * hv_netvsc_packet cannot be deallocated
 	 */
-	for (i = 0; i < packet->page_buf_cnt; i++) {
-		data = kmap_atomic(pfn_to_page(packet->page_buf[i].pfn),
-					       KM_IRQ1);
-		data = (void *)(unsigned long)data +
-				packet->page_buf[i].offset;
-
-		memcpy(skb_put(skb, packet->page_buf[i].len), data,
-		       packet->page_buf[i].len);
-
-		kunmap_atomic((void *)((unsigned long)data -
-				       packet->page_buf[i].offset), KM_IRQ1);
-	}
-
-	local_irq_restore(flags);
+	memcpy(skb_put(skb, packet->total_data_buflen), packet->data,
+		packet->total_data_buflen);
 
 	skb->protocol = eth_type_trans(skb, net);
 	skb->ip_summed = CHECKSUM_NONE;

drivers/net/hyperv/rndis_filter.c

@@ -309,7 +309,6 @@ static void rndis_filter_receive_data(struct rndis_device *dev,
 {
 	struct rndis_packet *rndis_pkt;
 	u32 data_offset;
-	int i;
 
 	rndis_pkt = &msg->msg.pkt;
 
@@ -322,17 +321,7 @@ static void rndis_filter_receive_data(struct rndis_device *dev,
 	data_offset = RNDIS_HEADER_SIZE + rndis_pkt->data_offset;
 
 	pkt->total_data_buflen -= data_offset;
-	pkt->page_buf[0].offset += data_offset;
-	pkt->page_buf[0].len -= data_offset;
-
-	/* Drop the 0th page, if rndis data go beyond page boundary */
-	if (pkt->page_buf[0].offset >= PAGE_SIZE) {
-		pkt->page_buf[1].offset = pkt->page_buf[0].offset - PAGE_SIZE;
-		pkt->page_buf[1].len -= pkt->page_buf[1].offset;
-		pkt->page_buf_cnt--;
-		for (i = 0; i < pkt->page_buf_cnt; i++)
-			pkt->page_buf[i] = pkt->page_buf[i+1];
-	}
+	pkt->data = (void *)((unsigned long)pkt->data + data_offset);
 
 	pkt->is_data_pkt = true;
 
@@ -367,11 +356,7 @@ int rndis_filter_receive(struct hv_device *dev,
 		return -ENODEV;
 	}
 
-	rndis_hdr = (struct rndis_message *)kmap_atomic(
-			pfn_to_page(pkt->page_buf[0].pfn), KM_IRQ0);
-
-	rndis_hdr = (void *)((unsigned long)rndis_hdr +
-			pkt->page_buf[0].offset);
+	rndis_hdr = pkt->data;
 
 	/* Make sure we got a valid rndis message */
 	if ((rndis_hdr->ndis_msg_type != REMOTE_NDIS_PACKET_MSG) &&
@@ -387,8 +372,6 @@ int rndis_filter_receive(struct hv_device *dev,
 			sizeof(struct rndis_message) :
 			rndis_hdr->msg_len);
 
-	kunmap_atomic(rndis_hdr - pkt->page_buf[0].offset, KM_IRQ0);
-
 	dump_rndis_message(dev, &rndis_msg);
 
 	switch (rndis_msg.ndis_msg_type) {