[PATCH 17/18] xen/sndfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross <jgross@xxxxxxxx>]

Simplify sndfront's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 sound/xen/xen_snd_front_evtchnl.c | 41 +++++++------------------------
 1 file changed, 9 insertions(+), 32 deletions(-)

diff --git a/sound/xen/xen_snd_front_evtchnl.c 
b/sound/xen/xen_snd_front_evtchnl.c
index 3e21369c8216..32d42fd3f7ac 100644
--- a/sound/xen/xen_snd_front_evtchnl.c
+++ b/sound/xen/xen_snd_front_evtchnl.c
@@ -143,12 +143,12 @@ void xen_snd_front_evtchnl_flush(struct 
xen_snd_front_evtchnl *channel)
 static void evtchnl_free(struct xen_snd_front_info *front_info,
                         struct xen_snd_front_evtchnl *channel)
 {
-       unsigned long page = 0;
+       void *page = NULL;
 
        if (channel->type == EVTCHNL_TYPE_REQ)
-               page = (unsigned long)channel->u.req.ring.sring;
+               page = channel->u.req.ring.sring;
        else if (channel->type == EVTCHNL_TYPE_EVT)
-               page = (unsigned long)channel->u.evt.page;
+               page = channel->u.evt.page;
 
        if (!page)
                return;
@@ -167,10 +167,7 @@ static void evtchnl_free(struct xen_snd_front_info 
*front_info,
                xenbus_free_evtchn(front_info->xb_dev, channel->port);
 
        /* End access and free the page. */
-       if (channel->gref != INVALID_GRANT_REF)
-               gnttab_end_foreign_access(channel->gref, page);
-       else
-               free_page(page);
+       xenbus_teardown_ring(&page, 1, &channel->gref);
 
        memset(channel, 0, sizeof(*channel));
 }
@@ -196,8 +193,7 @@ static int evtchnl_alloc(struct xen_snd_front_info 
*front_info, int index,
                         enum xen_snd_front_evtchnl_type type)
 {
        struct xenbus_device *xb_dev = front_info->xb_dev;
-       unsigned long page;
-       grant_ref_t gref;
+       void *page;
        irq_handler_t handler;
        char *handler_name = NULL;
        int ret;
@@ -207,12 +203,9 @@ static int evtchnl_alloc(struct xen_snd_front_info 
*front_info, int index,
        channel->index = index;
        channel->front_info = front_info;
        channel->state = EVTCHNL_STATE_DISCONNECTED;
-       channel->gref = INVALID_GRANT_REF;
-       page = get_zeroed_page(GFP_KERNEL);
-       if (!page) {
-               ret = -ENOMEM;
+       ret = xenbus_setup_ring(xb_dev, GFP_KERNEL, &page, 1, &channel->gref);
+       if (ret)
                goto fail;
-       }
 
        handler_name = kasprintf(GFP_KERNEL, "%s-%s", XENSND_DRIVER_NAME,
                                 type == EVTCHNL_TYPE_REQ ?
@@ -226,33 +219,19 @@ static int evtchnl_alloc(struct xen_snd_front_info 
*front_info, int index,
        mutex_init(&channel->ring_io_lock);
 
        if (type == EVTCHNL_TYPE_REQ) {
-               struct xen_sndif_sring *sring = (struct xen_sndif_sring *)page;
+               struct xen_sndif_sring *sring = page;
 
                init_completion(&channel->u.req.completion);
                mutex_init(&channel->u.req.req_io_lock);
                SHARED_RING_INIT(sring);
                FRONT_RING_INIT(&channel->u.req.ring, sring, XEN_PAGE_SIZE);
 
-               ret = xenbus_grant_ring(xb_dev, sring, 1, &gref);
-               if (ret < 0) {
-                       channel->u.req.ring.sring = NULL;
-                       goto fail;
-               }
-
                handler = evtchnl_interrupt_req;
        } else {
-               ret = gnttab_grant_foreign_access(xb_dev->otherend_id,
-                                                 virt_to_gfn((void *)page), 0);
-               if (ret < 0)
-                       goto fail;
-
-               channel->u.evt.page = (struct xensnd_event_page *)page;
-               gref = ret;
+               channel->u.evt.page = page;
                handler = evtchnl_interrupt_evt;
        }
 
-       channel->gref = gref;
-
        ret = xenbus_alloc_evtchn(xb_dev, &channel->port);
        if (ret < 0)
                goto fail;
@@ -279,8 +258,6 @@ static int evtchnl_alloc(struct xen_snd_front_info 
*front_info, int index,
        return 0;
 
 fail:
-       if (page)
-               free_page(page);
        kfree(handler_name);
        dev_err(&xb_dev->dev, "Failed to allocate ring: %d\n", ret);
        return ret;
-- 
2.34.1