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[Xen-devel] [PATCH 2/2] xen/gnt{dev, alloc}: reserve event channels for notify



When using the unmap notify ioctl, the event channel used for
notification needs to be reserved to avoid it being deallocated prior to
sending the notification.

Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---
 drivers/xen/gntalloc.c |   14 +++++++++++++-
 drivers/xen/gntdev.c   |   11 +++++++++++
 2 files changed, 24 insertions(+), 1 deletions(-)

diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index f6832f4..a739fb1 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -178,8 +178,10 @@ static void __del_gref(struct gntalloc_gref *gref)
                tmp[gref->notify.pgoff] = 0;
                kunmap(gref->page);
        }
-       if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
+       if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
                notify_remote_via_evtchn(gref->notify.event);
+               evtchn_put(gref->notify.event);
+       }
 
        gref->notify.flags = 0;
 
@@ -396,6 +398,16 @@ static long gntalloc_ioctl_unmap_notify(struct 
gntalloc_file_private_data *priv,
                goto unlock_out;
        }
 
+       if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
+               if (evtchn_get(op.event_channel_port)) {
+                       rc = -EINVAL;
+                       goto unlock_out;
+               }
+       }
+
+       if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
+               evtchn_put(gref->notify.event);
+
        gref->notify.flags = op.action;
        gref->notify.pgoff = pgoff;
        gref->notify.event = op.event_channel_port;
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index f914b26..cfcc890 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -190,6 +190,7 @@ static void gntdev_put_map(struct grant_map *map)
 
        if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
                notify_remote_via_evtchn(map->notify.event);
+               evtchn_put(map->notify.event);
        }
 
        if (map->pages) {
@@ -596,6 +597,16 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, 
void __user *u)
                goto unlock_out;
        }
 
+       if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
+               if (evtchn_get(op.event_channel_port)) {
+                       rc = -EINVAL;
+                       goto unlock_out;
+               }
+       }
+
+       if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
+               evtchn_put(map->notify.event);
+
        map->notify.flags = op.action;
        map->notify.addr = op.index - (map->index << PAGE_SHIFT);
        map->notify.event = op.event_channel_port;
-- 
1.7.6.4


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