Subject: provide a variant of __RING_SIZE() that is an integer constant expression

Without that, gcc 4.5 won't compile (at least) netfront, where this is
being used to specify array sizes.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- head-2010-02-03.orig/drivers/xen/blkfront/block.h	2010-01-18 17:06:20.000000000 +0100
+++ head-2010-02-03/drivers/xen/blkfront/block.h	2010-02-24 10:23:50.000000000 +0100
@@ -87,7 +87,7 @@ struct blk_shadow {
 	unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 };
 
-#define BLK_RING_SIZE __RING_SIZE((blkif_sring_t *)0, PAGE_SIZE)
+#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
 
 /*
  * We have one of these per vbd, whether ide, scsi or 'other'.  They
--- head-2010-02-03.orig/drivers/xen/blktap/blktap.c	2010-01-04 13:22:46.000000000 +0100
+++ head-2010-02-03/drivers/xen/blktap/blktap.c	2010-02-24 10:24:04.000000000 +0100
@@ -70,7 +70,7 @@
  * mmap_alloc is initialised to 2 and should be adjustable on the fly via
  * sysfs.
  */
-#define BLK_RING_SIZE		__RING_SIZE((blkif_sring_t *)0, PAGE_SIZE)
+#define BLK_RING_SIZE		__CONST_RING_SIZE(blkif, PAGE_SIZE)
 #define MAX_DYNAMIC_MEM		BLK_RING_SIZE
 #define MAX_PENDING_REQS	BLK_RING_SIZE
 #define MMAP_PAGES (MAX_PENDING_REQS * BLKIF_MAX_SEGMENTS_PER_REQUEST)
--- head-2010-02-03.orig/drivers/xen/blktap2/blktap.h	2009-12-16 12:14:37.000000000 +0100
+++ head-2010-02-03/drivers/xen/blktap2/blktap.h	2010-02-24 10:24:14.000000000 +0100
@@ -69,7 +69,7 @@ extern int blktap_debug_level;
  * mmap_alloc is initialised to 2 and should be adjustable on the fly via
  * sysfs.
  */
-#define BLK_RING_SIZE		__RING_SIZE((blkif_sring_t *)0, PAGE_SIZE)
+#define BLK_RING_SIZE		__CONST_RING_SIZE(blkif, PAGE_SIZE)
 #define MAX_DYNAMIC_MEM		BLK_RING_SIZE
 #define MAX_PENDING_REQS	BLK_RING_SIZE
 #define MMAP_PAGES (MAX_PENDING_REQS * BLKIF_MAX_SEGMENTS_PER_REQUEST)
--- head-2010-02-03.orig/drivers/xen/netback/common.h	2010-01-25 14:01:52.000000000 +0100
+++ head-2010-02-03/drivers/xen/netback/common.h	2010-02-24 10:24:57.000000000 +0100
@@ -177,8 +177,8 @@ extern
 void netif_accel_init(void);
 
 
-#define NET_TX_RING_SIZE __RING_SIZE((netif_tx_sring_t *)0, PAGE_SIZE)
-#define NET_RX_RING_SIZE __RING_SIZE((netif_rx_sring_t *)0, PAGE_SIZE)
+#define NET_TX_RING_SIZE __CONST_RING_SIZE(netif_tx, PAGE_SIZE)
+#define NET_RX_RING_SIZE __CONST_RING_SIZE(netif_rx, PAGE_SIZE)
 
 void netif_disconnect(netif_t *netif);
 
--- head-2010-02-03.orig/drivers/xen/netfront/netfront.h	2010-01-28 10:33:49.000000000 +0100
+++ head-2010-02-03/drivers/xen/netfront/netfront.h	2010-02-24 10:25:14.000000000 +0100
@@ -38,8 +38,8 @@
 #include <linux/skbuff.h>
 #include <linux/list.h>
 
-#define NET_TX_RING_SIZE __RING_SIZE((struct netif_tx_sring *)0, PAGE_SIZE)
-#define NET_RX_RING_SIZE __RING_SIZE((struct netif_rx_sring *)0, PAGE_SIZE)
+#define NET_TX_RING_SIZE __CONST_RING_SIZE(netif_tx, PAGE_SIZE)
+#define NET_RX_RING_SIZE __CONST_RING_SIZE(netif_rx, PAGE_SIZE)
 
 #include <xen/xenbus.h>
 
--- head-2010-02-03.orig/drivers/xen/scsifront/common.h	2010-01-28 10:33:16.000000000 +0100
+++ head-2010-02-03/drivers/xen/scsifront/common.h	2010-02-24 10:25:34.000000000 +0100
@@ -70,8 +70,7 @@
 #define VSCSIIF_MAX_TARGET          64
 #define VSCSIIF_MAX_LUN             255
 
-#define VSCSIIF_RING_SIZE	\
-    __RING_SIZE((struct vscsiif_sring *)0, PAGE_SIZE)
+#define VSCSIIF_RING_SIZE	__CONST_RING_SIZE(vscsiif, PAGE_SIZE)
 #define VSCSIIF_MAX_REQS	VSCSIIF_RING_SIZE
 
 struct vscsifrnt_shadow {
--- head-2010-02-03.orig/include/xen/interface/io/ring.h	2010-01-19 16:01:04.000000000 +0100
+++ head-2010-02-03/include/xen/interface/io/ring.h	2010-02-24 10:15:52.000000000 +0100
@@ -50,6 +50,12 @@ typedef unsigned int RING_IDX;
  * A ring contains as many entries as will fit, rounded down to the nearest 
  * power of two (so we can mask with (size-1) to loop around).
  */
+#define __CONST_RING_SIZE(_s, _sz) \
+    (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
+	    sizeof(((struct _s##_sring *)0)->ring[0])))
+/*
+ * The same for passing in an actual pointer instead of a name tag.
+ */
 #define __RING_SIZE(_s, _sz) \
     (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
 
--- head-2010-02-03.orig/include/xen/interface/io/usbif.h	2009-10-15 11:45:41.000000000 +0200
+++ head-2010-02-03/include/xen/interface/io/usbif.h	2010-02-24 10:17:25.000000000 +0100
@@ -128,7 +128,7 @@ struct usbif_urb_response {
 typedef struct usbif_urb_response usbif_urb_response_t;
 
 DEFINE_RING_TYPES(usbif_urb, struct usbif_urb_request, struct usbif_urb_response);
-#define USB_URB_RING_SIZE __RING_SIZE((struct usbif_urb_sring *)0, PAGE_SIZE)
+#define USB_URB_RING_SIZE __CONST_RING_SIZE(usbif_urb, PAGE_SIZE)
 
 /*
  * RING for notifying connect/disconnect events to frontend
@@ -146,6 +146,6 @@ struct usbif_conn_response {
 typedef struct usbif_conn_response usbif_conn_response_t;
 
 DEFINE_RING_TYPES(usbif_conn, struct usbif_conn_request, struct usbif_conn_response);
-#define USB_CONN_RING_SIZE __RING_SIZE((struct usbif_conn_sring *)0, PAGE_SIZE)
+#define USB_CONN_RING_SIZE __CONST_RING_SIZE(usbif_conn, PAGE_SIZE)
 
 #endif /* __XEN_PUBLIC_IO_USBIF_H__ */