[PATCH 16/18] xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross <jgross@xxxxxxxx>]

Simplify xen-hcd's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 drivers/usb/host/xen-hcd.c | 55 +++++++++-----------------------------
 1 file changed, 13 insertions(+), 42 deletions(-)

diff --git a/drivers/usb/host/xen-hcd.c b/drivers/usb/host/xen-hcd.c
index 9cbc7c2dab02..0acb68eb37ee 100644
--- a/drivers/usb/host/xen-hcd.c
+++ b/drivers/usb/host/xen-hcd.c
@@ -1098,19 +1098,10 @@ static void xenhcd_destroy_rings(struct xenhcd_info 
*info)
                unbind_from_irqhandler(info->irq, info);
        info->irq = 0;
 
-       if (info->urb_ring_ref != INVALID_GRANT_REF) {
-               gnttab_end_foreign_access(info->urb_ring_ref,
-                                         (unsigned long)info->urb_ring.sring);
-               info->urb_ring_ref = INVALID_GRANT_REF;
-       }
-       info->urb_ring.sring = NULL;
-
-       if (info->conn_ring_ref != INVALID_GRANT_REF) {
-               gnttab_end_foreign_access(info->conn_ring_ref,
-                                         (unsigned long)info->conn_ring.sring);
-               info->conn_ring_ref = INVALID_GRANT_REF;
-       }
-       info->conn_ring.sring = NULL;
+       xenbus_teardown_ring((void **)&info->urb_ring.sring, 1,
+                            &info->urb_ring_ref);
+       xenbus_teardown_ring((void **)&info->conn_ring.sring, 1,
+                            &info->conn_ring_ref);
 }
 
 static int xenhcd_setup_rings(struct xenbus_device *dev,
@@ -1118,47 +1109,27 @@ static int xenhcd_setup_rings(struct xenbus_device *dev,
 {
        struct xenusb_urb_sring *urb_sring;
        struct xenusb_conn_sring *conn_sring;
-       grant_ref_t gref;
        int err;
 
-       info->urb_ring_ref = INVALID_GRANT_REF;
        info->conn_ring_ref = INVALID_GRANT_REF;
-
-       urb_sring = (struct xenusb_urb_sring *)get_zeroed_page(
-                                                       GFP_NOIO | __GFP_HIGH);
-       if (!urb_sring) {
-               xenbus_dev_fatal(dev, -ENOMEM, "allocating urb ring");
-               return -ENOMEM;
+       err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH,
+                               (void **)&urb_sring, 1, &info->urb_ring_ref);
+       if (err) {
+               xenbus_dev_fatal(dev, err, "allocating urb ring");
+               return err;
        }
        SHARED_RING_INIT(urb_sring);
        FRONT_RING_INIT(&info->urb_ring, urb_sring, PAGE_SIZE);
 
-       err = xenbus_grant_ring(dev, urb_sring, 1, &gref);
-       if (err < 0) {
-               free_page((unsigned long)urb_sring);
-               info->urb_ring.sring = NULL;
-               goto fail;
-       }
-       info->urb_ring_ref = gref;
-
-       conn_sring = (struct xenusb_conn_sring *)get_zeroed_page(
-                                                       GFP_NOIO | __GFP_HIGH);
-       if (!conn_sring) {
-               xenbus_dev_fatal(dev, -ENOMEM, "allocating conn ring");
-               err = -ENOMEM;
+       err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH,
+                               (void **)&conn_sring, 1, &info->conn_ring_ref);
+       if (err) {
+               xenbus_dev_fatal(dev, err, "allocating conn ring");
                goto fail;
        }
        SHARED_RING_INIT(conn_sring);
        FRONT_RING_INIT(&info->conn_ring, conn_sring, PAGE_SIZE);
 
-       err = xenbus_grant_ring(dev, conn_sring, 1, &gref);
-       if (err < 0) {
-               free_page((unsigned long)conn_sring);
-               info->conn_ring.sring = NULL;
-               goto fail;
-       }
-       info->conn_ring_ref = gref;
-
        err = xenbus_alloc_evtchn(dev, &info->evtchn);
        if (err) {
                xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
-- 
2.34.1