Staging: hv: transmit scatter gather support

The transmit management of pages was confusing for handling
fragmented SKB's. (But since NETIF_F_SG was never set, the code was never hit).

The parameter AdditionalRequestPageBufferCount is always one,
(and leads to ugly code), so just inline and add comments.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 22 insertions, 32 deletions

diff --git a/drivers/staging/hv/RndisFilter.c b/drivers/staging/hv/RndisFilter.c
index 861139677e3..de4bc80341c 100644
--- a/drivers/staging/hv/RndisFilter.c
+++ b/drivers/staging/hv/RndisFilter.c
@@ -624,7 +624,6 @@ int RndisFilterInit(struct netvsc_driver *Driver)
                    sizeof(struct rndis_filter_packet));
 
         Driver->RequestExtSize = sizeof(struct rndis_filter_packet);
-        Driver->AdditionalRequestPageBufferCount = 1; /* For rndis header */
 
         /* Driver->Context = rndisDriver; */
 
diff --git a/drivers/staging/hv/netvsc_drv.c b/drivers/staging/hv/netvsc_drv.c
index b02455cfe23..4124979835a 100644
--- a/drivers/staging/hv/netvsc_drv.c
+++ b/drivers/staging/hv/netvsc_drv.c
@@ -144,27 +144,21 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
                 (struct netvsc_driver_context *)driver_ctx;
         struct netvsc_driver *net_drv_obj = &net_drv_ctx->drv_obj;
         struct hv_netvsc_packet *packet;
-        int i;
         int ret;
-        int num_frags;
+        unsigned int i, num_pages;
         int retries = 0;
 
         DPRINT_ENTER(NETVSC_DRV);
 
-        /* Support only 1 chain of frags */
-        ASSERT(skb_shinfo(skb)->frag_list == NULL);
-        ASSERT(skb->dev == net);
-
         DPRINT_DBG(NETVSC_DRV, "xmit packet - len %d data_len %d",
                    skb->len, skb->data_len);
 
-        /* Add 1 for skb->data and any additional ones requested */
-        num_frags = skb_shinfo(skb)->nr_frags + 1 +
-                    net_drv_obj->AdditionalRequestPageBufferCount;
+        /* Add 1 for skb->data and additional one for RNDIS */
+        num_pages = skb_shinfo(skb)->nr_frags + 1 + 1;
 
         /* Allocate a netvsc packet based on # of frags. */
         packet = kzalloc(sizeof(struct hv_netvsc_packet) +
-                         (num_frags * sizeof(struct hv_page_buffer)) +
+                         (num_pages * sizeof(struct hv_page_buffer)) +
                          net_drv_obj->RequestExtSize, GFP_ATOMIC);
         if (!packet) {
                 DPRINT_ERR(NETVSC_DRV, "unable to allocate hv_netvsc_packet");
@@ -173,36 +167,30 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
 
         packet->Extension = (void *)(unsigned long)packet +
                                 sizeof(struct hv_netvsc_packet) +
-                                    (num_frags * sizeof(struct hv_page_buffer));
+                                    (num_pages * sizeof(struct hv_page_buffer));
 
         /* Setup the rndis header */
-        packet->PageBufferCount = num_frags;
+        packet->PageBufferCount = num_pages;
 
         /* TODO: Flush all write buffers/ memory fence ??? */
         /* wmb(); */
 
         /* Initialize it from the skb */
-        ASSERT(skb->data);
         packet->TotalDataBufferLength   = skb->len;
 
-        /*
-         * Start filling in the page buffers starting at
-         * AdditionalRequestPageBufferCount offset
-         */
-        packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Pfn = virt_to_phys(skb->data) >> PAGE_SHIFT;
-        packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Offset = (unsigned long)skb->data & (PAGE_SIZE - 1);
-        packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Length = skb->len - skb->data_len;
-
-        ASSERT((skb->len - skb->data_len) <= PAGE_SIZE);
-
-        for (i = net_drv_obj->AdditionalRequestPageBufferCount + 1;
-             i < num_frags; i++) {
-                packet->PageBuffers[i].Pfn =
-                        page_to_pfn(skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].page);
-                packet->PageBuffers[i].Offset =
-                        skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].page_offset;
-                packet->PageBuffers[i].Length =
-                        skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].size;
+        /* Start filling in the page buffers starting after RNDIS buffer. */
+        packet->PageBuffers[1].Pfn = virt_to_phys(skb->data) >> PAGE_SHIFT;
+        packet->PageBuffers[1].Offset
+                = (unsigned long)skb->data & (PAGE_SIZE - 1);
+        packet->PageBuffers[1].Length = skb_headlen(skb);
+
+        /* Additional fragments are after SKB data */
+        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+                skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+
+                packet->PageBuffers[i+2].Pfn = page_to_pfn(f->page);
+                packet->PageBuffers[i+2].Offset = f->page_offset;
+                packet->PageBuffers[i+2].Length = f->size;
         }
 
         /* Set the completion routine */
@@ -423,6 +411,9 @@ static int netvsc_probe(struct device *device)
 
         net->netdev_ops = &device_ops;
 
+        /* TODO: Add GSO and Checksum offload */
+        net->features = NETIF_F_SG;
+
         SET_NETDEV_DEV(net, device);
 
         ret = register_netdev(net);