xen-netfront: refactor making Tx requests

Eliminate all the duplicate code for making Tx requests by
consolidating them into a single xennet_make_one_txreq() function.

xennet_make_one_txreq() and xennet_make_txreqs() work with pages and
offsets so it will be easier to make netfront handle highmem frags in
the future.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 803ff5356faa88530297fcc36efeebd6b44e7513..01a4350eb313cdea4ee89b1d0c9fc811344662da 100644 (file)
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -421,99 +421,56 @@ static void xennet_tx_buf_gc(struct netfront_queue *queue)
        xennet_maybe_wake_tx(queue);
 }
 
-static void xennet_make_frags(struct sk_buff *skb, struct netfront_queue *queue,
-                             struct xen_netif_tx_request *tx)
-{
-       char *data = skb->data;
-       unsigned long mfn;
-       RING_IDX prod = queue->tx.req_prod_pvt;
-       int frags = skb_shinfo(skb)->nr_frags;
-       unsigned int offset = offset_in_page(data);
-       unsigned int len = skb_headlen(skb);
+static struct xen_netif_tx_request *xennet_make_one_txreq(
+       struct netfront_queue *queue, struct sk_buff *skb,
+       struct page *page, unsigned int offset, unsigned int len)
+{
        unsigned int id;
+       struct xen_netif_tx_request *tx;
        grant_ref_t ref;
-       int i;
 
-       /* While the header overlaps a page boundary (including being
-          larger than a page), split it it into page-sized chunks. */
-       while (len > PAGE_SIZE - offset) {
-               tx->size = PAGE_SIZE - offset;
-               tx->flags |= XEN_NETTXF_more_data;
-               len -= tx->size;
-               data += tx->size;
-               offset = 0;
+       len = min_t(unsigned int, PAGE_SIZE - offset, len);
 
-               id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs);
-               queue->tx_skbs[id].skb = skb_get(skb);
-               tx = RING_GET_REQUEST(&queue->tx, prod++);
-               tx->id = id;
-               ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
-               BUG_ON((signed short)ref < 0);
+       id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs);
+       tx = RING_GET_REQUEST(&queue->tx, queue->tx.req_prod_pvt++);
+       ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
+       BUG_ON((signed short)ref < 0);
 
-               mfn = virt_to_mfn(data);
-               gnttab_grant_foreign_access_ref(ref, queue->info->xbdev->otherend_id,
-                                               mfn, GNTMAP_readonly);
+       gnttab_grant_foreign_access_ref(ref, queue->info->xbdev->otherend_id,
+                                       page_to_mfn(page), GNTMAP_readonly);
 
-               queue->grant_tx_page[id] = virt_to_page(data);
-               tx->gref = queue->grant_tx_ref[id] = ref;
-               tx->offset = offset;
-               tx->size = len;
-               tx->flags = 0;
-       }
+       queue->tx_skbs[id].skb = skb;
+       queue->grant_tx_page[id] = page;
+       queue->grant_tx_ref[id] = ref;
 
-       /* Grant backend access to each skb fragment page. */
-       for (i = 0; i < frags; i++) {
-               skb_frag_t *frag = skb_shinfo(skb)->frags + i;
-               struct page *page = skb_frag_page(frag);
+       tx->id = id;
+       tx->gref = ref;
+       tx->offset = offset;
+       tx->size = len;
+       tx->flags = 0;
 
-               len = skb_frag_size(frag);
-               offset = frag->page_offset;
+       return tx;
+}
 
-               /* Skip unused frames from start of page */
-               page += offset >> PAGE_SHIFT;
-               offset &= ~PAGE_MASK;
+static struct xen_netif_tx_request *xennet_make_txreqs(
+       struct netfront_queue *queue, struct xen_netif_tx_request *tx,
+       struct sk_buff *skb, struct page *page,
+       unsigned int offset, unsigned int len)
+{
+       /* Skip unused frames from start of page */
+       page += offset >> PAGE_SHIFT;
+       offset &= ~PAGE_MASK;
 
-               while (len > 0) {
-                       unsigned long bytes;
-
-                       bytes = PAGE_SIZE - offset;
-                       if (bytes > len)
-                               bytes = len;
-
-                       tx->flags |= XEN_NETTXF_more_data;
-
-                       id = get_id_from_freelist(&queue->tx_skb_freelist,
-                                                 queue->tx_skbs);
-                       queue->tx_skbs[id].skb = skb_get(skb);
-                       tx = RING_GET_REQUEST(&queue->tx, prod++);
-                       tx->id = id;
-                       ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
-                       BUG_ON((signed short)ref < 0);
-
-                       mfn = pfn_to_mfn(page_to_pfn(page));
-                       gnttab_grant_foreign_access_ref(ref,
-                                                       queue->info->xbdev->otherend_id,
-                                                       mfn, GNTMAP_readonly);
-
-                       queue->grant_tx_page[id] = page;
-                       tx->gref = queue->grant_tx_ref[id] = ref;
-                       tx->offset = offset;
-                       tx->size = bytes;
-                       tx->flags = 0;
-
-                       offset += bytes;
-                       len -= bytes;
-
-                       /* Next frame */
-                       if (offset == PAGE_SIZE && len) {
-                               BUG_ON(!PageCompound(page));
-                               page++;
-                               offset = 0;
-                       }
-               }
+       while (len) {
+               tx->flags |= XEN_NETTXF_more_data;
+               tx = xennet_make_one_txreq(queue, skb_get(skb),
+                                          page, offset, len);
+               page++;
+               offset = 0;
+               len -= tx->size;
        }
 
-       queue->tx.req_prod_pvt = prod;
+       return tx;
 }
 
 /*
@@ -561,18 +518,15 @@ static u16 xennet_select_queue(struct net_device *dev, struct sk_buff *skb,
 
 static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
-       unsigned short id;
        struct netfront_info *np = netdev_priv(dev);
        struct netfront_stats *stats = this_cpu_ptr(np->stats);
-       struct xen_netif_tx_request *tx;
-       char *data = skb->data;
-       RING_IDX i;
-       grant_ref_t ref;
-       unsigned long mfn;
+       struct xen_netif_tx_request *tx, *first_tx;
+       unsigned int i;
        int notify;
        int slots;
-       unsigned int offset = offset_in_page(data);
-       unsigned int len = skb_headlen(skb);
+       struct page *page;
+       unsigned int offset;
+       unsigned int len;
        unsigned long flags;
        struct netfront_queue *queue = NULL;
        unsigned int num_queues = dev->real_num_tx_queues;
@@ -601,11 +555,12 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
                                    slots, skb->len);
                if (skb_linearize(skb))
                        goto drop;
-               data = skb->data;
-               offset = offset_in_page(data);
-               len = skb_headlen(skb);
        }
 
+       page = virt_to_page(skb->data);
+       offset = offset_in_page(skb->data);
+       len = skb_headlen(skb);
+
        spin_lock_irqsave(&queue->tx_lock, flags);
 
        if (unlikely(!netif_carrier_ok(dev) ||
@@ -615,25 +570,13 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
                goto drop;
        }
 
-       i = queue->tx.req_prod_pvt;
-
-       id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs);
-       queue->tx_skbs[id].skb = skb;
-
-       tx = RING_GET_REQUEST(&queue->tx, i);
+       /* First request for the linear area. */
+       first_tx = tx = xennet_make_one_txreq(queue, skb,
+                                             page, offset, len);
+       page++;
+       offset = 0;
+       len -= tx->size;
 
-       tx->id   = id;
-       ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
-       BUG_ON((signed short)ref < 0);
-       mfn = virt_to_mfn(data);
-       gnttab_grant_foreign_access_ref(
-               ref, queue->info->xbdev->otherend_id, mfn, GNTMAP_readonly);
-       queue->grant_tx_page[id] = virt_to_page(data);
-       tx->gref = queue->grant_tx_ref[id] = ref;
-       tx->offset = offset;
-       tx->size = len;
-
-       tx->flags = 0;
        if (skb->ip_summed == CHECKSUM_PARTIAL)
                /* local packet? */
                tx->flags |= XEN_NETTXF_csum_blank | XEN_NETTXF_data_validated;
@@ -641,11 +584,12 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
                /* remote but checksummed. */
                tx->flags |= XEN_NETTXF_data_validated;
 
+       /* Optional extra info after the first request. */
        if (skb_shinfo(skb)->gso_size) {
                struct xen_netif_extra_info *gso;
 
                gso = (struct xen_netif_extra_info *)
-                       RING_GET_REQUEST(&queue->tx, ++i);
+                       RING_GET_REQUEST(&queue->tx, queue->tx.req_prod_pvt++);
 
                tx->flags |= XEN_NETTXF_extra_info;
 
@@ -660,10 +604,19 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
                gso->flags = 0;
        }
 
-       queue->tx.req_prod_pvt = i + 1;
+       /* Requests for the rest of the linear area. */
+       tx = xennet_make_txreqs(queue, tx, skb, page, offset, len);
+
+       /* Requests for all the frags. */
+       for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+               skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+               tx = xennet_make_txreqs(queue, tx, skb,
+                                       skb_frag_page(frag), frag->page_offset,
+                                       skb_frag_size(frag));
+       }
 
-       xennet_make_frags(skb, queue, tx);
-       tx->size = skb->len;
+       /* First request has the packet length. */
+       first_tx->size = skb->len;
 
        RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&queue->tx, notify);
        if (notify)