Drivers: net: hyperv: Enable scatter gather I/O

Cleanup the code and enable scatter gather I/O.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 9ef6be9..1f7b12f 100644 (file)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -140,21 +140,123 @@ static void netvsc_xmit_completion(void *context)
                dev_kfree_skb_any(skb);
 }
 
+static u32 fill_pg_buf(struct page *page, u32 offset, u32 len,
+                       struct hv_page_buffer *pb)
+{
+       int j = 0;
+
+       /* Deal with compund pages by ignoring unused part
+        * of the page.
+        */
+       page += (offset >> PAGE_SHIFT);
+       offset &= ~PAGE_MASK;
+
+       while (len > 0) {
+               unsigned long bytes;
+
+               bytes = PAGE_SIZE - offset;
+               if (bytes > len)
+                       bytes = len;
+               pb[j].pfn = page_to_pfn(page);
+               pb[j].offset = offset;
+               pb[j].len = bytes;
+
+               offset += bytes;
+               len -= bytes;
+
+               if (offset == PAGE_SIZE && len) {
+                       page++;
+                       offset = 0;
+                       j++;
+               }
+       }
+
+       return j + 1;
+}
+
+static void init_page_array(void *hdr, u32 len, struct sk_buff *skb,
+                           struct hv_page_buffer *pb)
+{
+       u32 slots_used = 0;
+       char *data = skb->data;
+       int frags = skb_shinfo(skb)->nr_frags;
+       int i;
+
+       /* The packet is laid out thus:
+        * 1. hdr
+        * 2. skb linear data
+        * 3. skb fragment data
+        */
+       if (hdr != NULL)
+               slots_used += fill_pg_buf(virt_to_page(hdr),
+                                       offset_in_page(hdr),
+                                       len, &pb[slots_used]);
+
+       slots_used += fill_pg_buf(virt_to_page(data),
+                               offset_in_page(data),
+                               skb_headlen(skb), &pb[slots_used]);
+
+       for (i = 0; i < frags; i++) {
+               skb_frag_t *frag = skb_shinfo(skb)->frags + i;
+
+               slots_used += fill_pg_buf(skb_frag_page(frag),
+                                       frag->page_offset,
+                                       skb_frag_size(frag), &pb[slots_used]);
+       }
+}
+
+static int count_skb_frag_slots(struct sk_buff *skb)
+{
+       int i, frags = skb_shinfo(skb)->nr_frags;
+       int pages = 0;
+
+       for (i = 0; i < frags; i++) {
+               skb_frag_t *frag = skb_shinfo(skb)->frags + i;
+               unsigned long size = skb_frag_size(frag);
+               unsigned long offset = frag->page_offset;
+
+               /* Skip unused frames from start of page */
+               offset &= ~PAGE_MASK;
+               pages += PFN_UP(offset + size);
+       }
+       return pages;
+}
+
+static int netvsc_get_slots(struct sk_buff *skb)
+{
+       char *data = skb->data;
+       unsigned int offset = offset_in_page(data);
+       unsigned int len = skb_headlen(skb);
+       int slots;
+       int frag_slots;
+
+       slots = DIV_ROUND_UP(offset + len, PAGE_SIZE);
+       frag_slots = count_skb_frag_slots(skb);
+       return slots + frag_slots;
+}
+
 static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
 {
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_netvsc_packet *packet;
        int ret;
-       unsigned int i, num_pages, npg_data;
+       unsigned int num_data_pages;
 
-       /* Add multipages for skb->data and additional 2 for RNDIS */
-       npg_data = (((unsigned long)skb->data + skb_headlen(skb) - 1)
-               >> PAGE_SHIFT) - ((unsigned long)skb->data >> PAGE_SHIFT) + 1;
-       num_pages = skb_shinfo(skb)->nr_frags + npg_data + 2;
+       /* We will atmost need two pages to describe the rndis
+        * header. We can only transmit MAX_PAGE_BUFFER_COUNT number
+        * of pages in a single packet.
+        */
+       num_data_pages = netvsc_get_slots(skb) + 2;
+       if (num_data_pages > MAX_PAGE_BUFFER_COUNT) {
+               netdev_err(net, "Packet too big: %u\n", skb->len);
+               dev_kfree_skb(skb);
+               net->stats.tx_dropped++;
+               return NETDEV_TX_OK;
+       }
 
        /* Allocate a netvsc packet based on # of frags. */
        packet = kzalloc(sizeof(struct hv_netvsc_packet) +
-                        (num_pages * sizeof(struct hv_page_buffer)) +
+                        (num_data_pages * sizeof(struct hv_page_buffer)) +
                         sizeof(struct rndis_message) +
                         NDIS_VLAN_PPI_SIZE, GFP_ATOMIC);
        if (!packet) {
@@ -169,44 +271,17 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
        packet->vlan_tci = skb->vlan_tci;
 
        packet->extension = (void *)(unsigned long)packet +
-                               sizeof(struct hv_netvsc_packet) +
-                                   (num_pages * sizeof(struct hv_page_buffer));
+                       sizeof(struct hv_netvsc_packet) +
+                       (num_data_pages * sizeof(struct hv_page_buffer));
 
        /* If the rndis msg goes beyond 1 page, we will add 1 later */
-       packet->page_buf_cnt = num_pages - 1;
+       packet->page_buf_cnt = num_data_pages - 1;
 
        /* Initialize it from the skb */
        packet->total_data_buflen = skb->len;
 
        /* Start filling in the page buffers starting after RNDIS buffer. */
-       packet->page_buf[1].pfn = virt_to_phys(skb->data) >> PAGE_SHIFT;
-       packet->page_buf[1].offset
-               = (unsigned long)skb->data & (PAGE_SIZE - 1);
-       if (npg_data == 1)
-               packet->page_buf[1].len = skb_headlen(skb);
-       else
-               packet->page_buf[1].len = PAGE_SIZE
-                       - packet->page_buf[1].offset;
-
-       for (i = 2; i <= npg_data; i++) {
-               packet->page_buf[i].pfn = virt_to_phys(skb->data
-                       + PAGE_SIZE * (i-1)) >> PAGE_SHIFT;
-               packet->page_buf[i].offset = 0;
-               packet->page_buf[i].len = PAGE_SIZE;
-       }
-       if (npg_data > 1)
-               packet->page_buf[npg_data].len = (((unsigned long)skb->data
-                       + skb_headlen(skb) - 1) & (PAGE_SIZE - 1)) + 1;
-
-       /* Additional fragments are after SKB data */
-       for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
-               const skb_frag_t *f = &skb_shinfo(skb)->frags[i];
-
-               packet->page_buf[i+npg_data+1].pfn =
-                       page_to_pfn(skb_frag_page(f));
-               packet->page_buf[i+npg_data+1].offset = f->page_offset;
-               packet->page_buf[i+npg_data+1].len = skb_frag_size(f);
-       }
+       init_page_array(NULL, 0, skb, &packet->page_buf[1]);
 
        /* Set the completion routine */
        packet->completion.send.send_completion = netvsc_xmit_completion;
@@ -451,8 +526,8 @@ static int netvsc_probe(struct hv_device *dev,
        net->netdev_ops = &device_ops;
 
        /* TODO: Add GSO and Checksum offload */
-       net->hw_features = 0;
-       net->features = NETIF_F_HW_VLAN_CTAG_TX;
+       net->hw_features = NETIF_F_SG;
+       net->features = NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_SG;
 
        SET_ETHTOOL_OPS(net, &ethtool_ops);
        SET_NETDEV_DEV(net, &dev->device);