[Xen-devel] [PATCH] xen-netback: do not report success if backend_create_xenvif() fails

[Alexey Khoroshilov <khoroshilov@xxxxxxxxx>]

If xenvif_alloc() or xenbus_scanf() fail in backend_create_xenvif(),
xenbus is left in offline mode but netback_probe() reports success.

The patch implements propagation of error code for backend_create_xenvif().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
---
 drivers/net/xen-netback/xenbus.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 4e56a27f9689..fab0d4b42f58 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -39,7 +39,7 @@ struct backend_info {
 static int connect_rings(struct backend_info *be, struct xenvif_queue *queue);
 static void connect(struct backend_info *be);
 static int read_xenbus_vif_flags(struct backend_info *be);
-static void backend_create_xenvif(struct backend_info *be);
+static int backend_create_xenvif(struct backend_info *be);
 static void unregister_hotplug_status_watch(struct backend_info *be);
 static void set_backend_state(struct backend_info *be,
                              enum xenbus_state state);
@@ -352,7 +352,9 @@ static int netback_probe(struct xenbus_device *dev,
        be->state = XenbusStateInitWait;
 
        /* This kicks hotplug scripts, so do it immediately. */
-       backend_create_xenvif(be);
+       err = backend_create_xenvif(be);
+       if (err)
+               goto fail;
 
        return 0;
 
@@ -397,19 +399,19 @@ static int netback_uevent(struct xenbus_device *xdev,
 }
 
 
-static void backend_create_xenvif(struct backend_info *be)
+static int backend_create_xenvif(struct backend_info *be)
 {
        int err;
        long handle;
        struct xenbus_device *dev = be->dev;
 
        if (be->vif != NULL)
-               return;
+               return 0;
 
        err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
        if (err != 1) {
                xenbus_dev_fatal(dev, err, "reading handle");
-               return;
+               return (err < 0) ? err : -EINVAL;
        }
 
        be->vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
@@ -417,10 +419,11 @@ static void backend_create_xenvif(struct backend_info *be)
                err = PTR_ERR(be->vif);
                be->vif = NULL;
                xenbus_dev_fatal(dev, err, "creating interface");
-               return;
+               return err;
        }
 
        kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
+       return 0;
 }
 
 static void backend_disconnect(struct backend_info *be)
-- 
1.9.1


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