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path: root/drivers/xen/gntdev.c
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Diffstat (limited to 'drivers/xen/gntdev.c')
-rw-r--r--drivers/xen/gntdev.c34
1 files changed, 32 insertions, 2 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index afca14d9042e..99d8151c824a 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -193,8 +193,10 @@ static void gntdev_put_map(struct grant_map *map)
atomic_sub(map->count, &pages_mapped);
- if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
+ if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
notify_remote_via_evtchn(map->notify.event);
+ evtchn_put(map->notify.event);
+ }
if (map->pages) {
if (!use_ptemod)
@@ -312,7 +314,8 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
}
}
- err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
+ err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset,
+ pages, true);
if (err)
return err;
@@ -599,6 +602,8 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
struct ioctl_gntdev_unmap_notify op;
struct grant_map *map;
int rc;
+ int out_flags;
+ unsigned int out_event;
if (copy_from_user(&op, u, sizeof(op)))
return -EFAULT;
@@ -606,6 +611,21 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
return -EINVAL;
+ /* We need to grab a reference to the event channel we are going to use
+ * to send the notify before releasing the reference we may already have
+ * (if someone has called this ioctl twice). This is required so that
+ * it is possible to change the clear_byte part of the notification
+ * without disturbing the event channel part, which may now be the last
+ * reference to that event channel.
+ */
+ if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
+ if (evtchn_get(op.event_channel_port))
+ return -EINVAL;
+ }
+
+ out_flags = op.action;
+ out_event = op.event_channel_port;
+
spin_lock(&priv->lock);
list_for_each_entry(map, &priv->maps, next) {
@@ -624,12 +644,22 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
goto unlock_out;
}
+ out_flags = map->notify.flags;
+ out_event = map->notify.event;
+
map->notify.flags = op.action;
map->notify.addr = op.index - (map->index << PAGE_SHIFT);
map->notify.event = op.event_channel_port;
+
rc = 0;
+
unlock_out:
spin_unlock(&priv->lock);
+
+ /* Drop the reference to the event channel we did not save in the map */
+ if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
+ evtchn_put(out_event);
+
return rc;
}