[PATCH] 9p/xen: mark 9p transport device as closing when removing it

[Ariadne Conill <ariadne@ariadne.space>]

We need to do this so that we can signal to the other end that the
device is being removed, so that it will release its claim on the
underlying memory allocation.  Otherwise releasing the grant-table
entries is deferred resulting in a kernel oops since the pages have
already been freed.

Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Fixes: 71ebd71921e45 ("xen/9pfs: connect to the backend")
Signed-off-by: Ariadne Conill <ariadne@ariadne.space>
Signed-off-by: Alex Zenla <alex@xxxxxxxxx>
---
 net/9p/trans_xen.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index b9ff69c7522a..cde283c42dc6 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -312,6 +312,7 @@ static void xen_9pfs_front_remove(struct xenbus_device *dev)
 {
        struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
 
+       xenbus_switch_state(dev, XenbusStateClosing);
        dev_set_drvdata(&dev->dev, NULL);
        xen_9pfs_front_free(priv);
 }
-- 
2.52.0