[PATCH RFC 1/2] usbif.h: don't require PAGE_SIZE to be present

[Wei Liu <wei.liu2@citrix.com>]

If it is present, use it; otherwise use 4096. Also provide two new
macros to let user have control over the page size used to do
calculation.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Tim Deegan <tim@xen.org>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Juergen Gross <jgross@suse.com>
---
 xen/include/public/io/usbif.h | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/xen/include/public/io/usbif.h b/xen/include/public/io/usbif.h
index 4053c24..ac38318 100644
--- a/xen/include/public/io/usbif.h
+++ b/xen/include/public/io/usbif.h
@@ -216,6 +216,16 @@ struct usbif_urb_request {
 };
 typedef struct usbif_urb_request usbif_urb_request_t;
 
+/*
+ * Reference to PAGE_SIZE was overlooked when this header file was
+ * introduced. Respect PAGE_SIZE if defined, otherwise, use 4096.
+ */
+#ifdef PAGE_SIZE
+#define _USB_RING_PAGE_SIZE PAGE_SIZE
+#else
+#define _USB_RING_PAGE_SIZE 4096
+#endif
+
 struct usbif_urb_response {
 	uint16_t id; /* request id */
 	uint16_t start_frame;  /* start frame (ISO) */
@@ -226,7 +236,12 @@ 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 __CONST_RING_SIZE(usbif_urb, PAGE_SIZE)
+/*
+ * Please use _SIZE2 variant in new code, _SIZE variant is kept for
+ * backward-compatibility.
+ */
+#define USB_URB_RING_SIZE __CONST_RING_SIZE(usbif_urb, _USB_RING_PAGE_SIZE)
+#define USB_URB_RING_SIZE2(pgsize) __CONST_RING_SIZE(usbif_urb, (pgsize))
 
 /*
  * RING for notifying connect/disconnect events to frontend
@@ -248,6 +263,11 @@ 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 __CONST_RING_SIZE(usbif_conn, PAGE_SIZE)
+/*
+ * Please use _SIZE2 variant in new code, _SIZE variant is kept for
+ * backward-compatibility.
+ */
+#define USB_CONN_RING_SIZE  __CONST_RING_SIZE(usbif_conn, _USB_RING_PAGE_SIZE)
+#define USB_CONN_RING_SIZE2(pgsize) __CONST_RING_SIZE(usbif_conn, (pgsize))
 
 #endif /* __XEN_PUBLIC_IO_USBIF_H__ */
-- 
2.1.4


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