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path: root/drivers/net/xen-netback/common.h
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Diffstat (limited to 'drivers/net/xen-netback/common.h')
-rw-r--r--drivers/net/xen-netback/common.h19
1 files changed, 13 insertions, 6 deletions
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index ba30a6d9fefa..c955fc39d69a 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -101,6 +101,13 @@ struct xenvif_rx_meta {
#define MAX_PENDING_REQS 256
+/* It's possible for an skb to have a maximal number of frags
+ * but still be less than MAX_BUFFER_OFFSET in size. Thus the
+ * worst-case number of copy operations is MAX_SKB_FRAGS per
+ * ring slot.
+ */
+#define MAX_GRANT_COPY_OPS (MAX_SKB_FRAGS * XEN_NETIF_RX_RING_SIZE)
+
struct xenvif {
/* Unique identifier for this interface. */
domid_t domid;
@@ -141,13 +148,13 @@ struct xenvif {
*/
bool rx_event;
- /* Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
- * head/fragment page uses 2 copy operations because it
- * straddles two buffers in the frontend.
- */
- struct gnttab_copy grant_copy_op[2*XEN_NETIF_RX_RING_SIZE];
- struct xenvif_rx_meta meta[2*XEN_NETIF_RX_RING_SIZE];
+ /* This array is allocated seperately as it is large */
+ struct gnttab_copy *grant_copy_op;
+ /* We create one meta structure per ring request we consume, so
+ * the maximum number is the same as the ring size.
+ */
+ struct xenvif_rx_meta meta[XEN_NETIF_RX_RING_SIZE];
u8 fe_dev_addr[6];