virtio: clarify NO_NOTIFY flag usage

[linux-2.6-omap-h63xx.git] / include / linux / virtio_ring.h

diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 8cde10e792c4c362077887d207a11249af603cd4..abe481ed990e328bd6f5ec1f5212deeed07b9fea 100644 (file)
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -15,9 +15,13 @@
 /* This marks a buffer as write-only (otherwise read-only). */
 #define VRING_DESC_F_WRITE     2
 
-/* This means don't notify other side when buffer added. */
+/* The Host uses this in used->flags to advise the Guest: don't kick me when
+ * you add a buffer.  It's unreliable, so it's simply an optimization.  Guest
+ * will still kick if it's out of buffers. */
 #define VRING_USED_F_NO_NOTIFY 1
-/* This means don't interrupt guest when buffer consumed. */
+/* The Guest uses this in avail->flags to advise the Host: don't interrupt me
+ * when you consume a buffer.  It's unreliable, so it's simply an
+ * optimization.  */
 #define VRING_AVAIL_F_NO_INTERRUPT     1
 
 /* Virtio ring descriptors: 16 bytes.  These can chain together via "next". */
@@ -89,7 +93,7 @@ struct vring {
  * };
  */
 static inline void vring_init(struct vring *vr, unsigned int num, void *p,
-                             unsigned int pagesize)
+                             unsigned long pagesize)
 {
        vr->num = num;
        vr->desc = p;
@@ -98,7 +102,7 @@ static inline void vring_init(struct vring *vr, unsigned int num, void *p,
                            & ~(pagesize - 1));
 }
 
-static inline unsigned vring_size(unsigned int num, unsigned int pagesize)
+static inline unsigned vring_size(unsigned int num, unsigned long pagesize)
 {
        return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
                 + pagesize - 1) & ~(pagesize - 1))