1 files changed, 7 insertions, 19 deletions

diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
index da5b30771418..379291826261 100644
--- a/drivers/char/tpm/xen-tpmfront.c
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -126,16 +126,16 @@ static void vtpm_cancel(struct tpm_chip *chip)
 	notify_remote_via_evtchn(priv->evtchn);
 }
 
-static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
+static size_t shr_data_offset(struct vtpm_shared_page *shr)
 {
-	return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
+	return struct_size(shr, extra_pages, shr->nr_extra_pages);
 }
 
 static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
 	struct vtpm_shared_page *shr = priv->shr;
-	unsigned int offset = shr_data_offset(shr);
+	size_t offset = shr_data_offset(shr);
 
 	u32 ordinal;
 	unsigned long duration;
@@ -177,7 +177,7 @@ static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
 	struct vtpm_shared_page *shr = priv->shr;
-	unsigned int offset = shr_data_offset(shr);
+	size_t offset = shr_data_offset(shr);
 	size_t length = shr->length;
 
 	if (shr->state == VTPM_STATE_IDLE)
@@ -253,20 +253,12 @@ static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
 	struct xenbus_transaction xbt;
 	const char *message = NULL;
 	int rv;
-	grant_ref_t gref;
 
-	priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
-	if (!priv->shr) {
-		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
-		return -ENOMEM;
-	}
-
-	rv = xenbus_grant_ring(dev, priv->shr, 1, &gref);
+	rv = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&priv->shr, 1,
+			       &priv->ring_ref);
 	if (rv < 0)
 		return rv;
 
-	priv->ring_ref = gref;
-
 	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
 	if (rv)
 		return rv;
@@ -331,11 +323,7 @@ static void ring_free(struct tpm_private *priv)
 	if (!priv)
 		return;
 
-	if (priv->ring_ref)
-		gnttab_end_foreign_access(priv->ring_ref, 0,
-				(unsigned long)priv->shr);
-	else
-		free_page((unsigned long)priv->shr);
+	xenbus_teardown_ring((void **)&priv->shr, 1, &priv->ring_ref);
 
 	if (priv->irq)
 		unbind_from_irqhandler(priv->irq, priv);