Free grant reference when block device shuts down.

Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>

diff --git a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
index d3caf467c85122297bb11d2033197a8d8a179a30..136f7d68d90cff11c51bcd93e894da49b2daee12 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
@@ -58,6 +58,7 @@ static unsigned int blkif_state = BLKIF_STATE_DISCONNECTED;
 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
     (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLKIF_RING_SIZE)
 #define GRANTREF_INVALID (1<<15)
+#define GRANT_INVALID_REF      (0xFFFF)
 
 static int recovery = 0; /* Recovery in progress: protected by blkif_io_lock */
 
@@ -368,6 +369,9 @@ static void blkif_free(struct blkfront_info *info)
                free_page((unsigned long)info->ring.sring);
                info->ring.sring = NULL;
        }
+       if (info->ring_ref != GRANT_INVALID_REF)
+               gnttab_end_foreign_access(info->ring_ref, 0);
+       info->ring_ref = GRANT_INVALID_REF;
        unbind_evtchn_from_irqhandler(info->evtchn, info); 
        info->evtchn = 0;
 }
@@ -502,6 +506,8 @@ static int setup_blkring(struct xenbus_device *dev, struct blkfront_info *info)
        evtchn_op_t op = { .cmd = EVTCHNOP_alloc_unbound };
        int err;
 
+       info->ring_ref = GRANT_INVALID_REF;
+
        sring = (void *)__get_free_page(GFP_KERNEL);
        if (!sring) {
                xenbus_dev_error(dev, -ENOMEM, "allocating shared ring");
@@ -524,6 +530,7 @@ static int setup_blkring(struct xenbus_device *dev, struct blkfront_info *info)
        err = HYPERVISOR_event_channel_op(&op);
        if (err) {
                gnttab_end_foreign_access(info->ring_ref, 0);
+               info->ring_ref = GRANT_INVALID_REF;
                free_page((unsigned long)info->ring.sring);
                info->ring.sring = 0;
                xenbus_dev_error(dev, err, "allocating event channel");