[xen] Skip probing of any unsupported device types

Xen 4.4 includes the device "device/suspend/event-channel" which does
not have a "backend" key.  This currently causes the entire XenBus
device tree probe to fail.

Fix by skipping probe attempts for device types for which there is no
iPXE driver.

Debugged-by: Eytan Heidingsfeld <eytanh@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/interface/xen/xenbus.c b/src/interface/xen/xenbus.c
index c328af44319c81dcd6d20161cbdc5bc7c9dd527b..5dd01dfa31a8ee0cbe56943665997cbde1524de6 100644 (file)
--- a/src/interface/xen/xenbus.c
+++ b/src/interface/xen/xenbus.c
@@ -206,13 +206,14 @@ static struct xen_driver * xenbus_find_driver ( const char *type ) {
  *
  * @v xen              Xen hypervisor
  * @v parent           Parent device
- * @v type             Device type
  * @v instance         Device instance
+ * @v driver           Device driver
  * @ret rc             Return status code
  */
 static int xenbus_probe_device ( struct xen_hypervisor *xen,
-                                struct device *parent, const char *type,
-                                const char *instance ) {
+                                struct device *parent, const char *instance,
+                                struct xen_driver *driver ) {
+       const char *type = driver->type;
        struct xen_device *xendev;
        size_t key_len;
        int rc;
@@ -234,6 +235,10 @@ static int xenbus_probe_device ( struct xen_hypervisor *xen,
        xendev->xen = xen;
        xendev->key = ( ( void * ) ( xendev + 1 ) );
        snprintf ( xendev->key, key_len, "device/%s/%s", type, instance );
+       xendev->driver = driver;
+       xendev->dev.driver_name = driver->name;
+       DBGC ( xendev, "XENBUS %s has driver \"%s\"\n", xendev->key,
+              xendev->driver->name );
 
        /* Read backend key */
        if ( ( rc = xenstore_read ( xen, &xendev->backend, xendev->key,
@@ -253,18 +258,6 @@ static int xenbus_probe_device ( struct xen_hypervisor *xen,
        DBGC ( xendev, "XENBUS %s backend=\"%s\" in domain %ld\n",
               xendev->key, xendev->backend, xendev->backend_id );
 
-       /* Look for a driver */
-       xendev->driver = xenbus_find_driver ( type );
-       if ( ! xendev->driver ) {
-               DBGC ( xendev, "XENBUS %s has no driver\n", xendev->key );
-               /* Not a fatal error */
-               rc = 0;
-               goto err_no_driver;
-       }
-       xendev->dev.driver_name = xendev->driver->name;
-       DBGC ( xendev, "XENBUS %s has driver \"%s\"\n", xendev->key,
-              xendev->driver->name );
-
        /* Probe driver */
        if ( ( rc = xendev->driver->probe ( xendev ) ) != 0 ) {
                DBGC ( xendev, "XENBUS could not probe %s: %s\n",
@@ -276,7 +269,6 @@ static int xenbus_probe_device ( struct xen_hypervisor *xen,
 
        xendev->driver->remove ( xendev );
  err_probe:
- err_no_driver:
  err_read_backend_id:
        free ( xendev->backend );
  err_read_backend:
@@ -310,11 +302,21 @@ static void xenbus_remove_device ( struct xen_device *xendev ) {
  */
 static int xenbus_probe_type ( struct xen_hypervisor *xen,
                               struct device *parent, const char *type ) {
+       struct xen_driver *driver;
        char *children;
        char *child;
        size_t len;
        int rc;
 
+       /* Look for a driver */
+       driver = xenbus_find_driver ( type );
+       if ( ! driver ) {
+               DBGC ( xen, "XENBUS has no driver for \"%s\" devices\n", type );
+               /* Not a fatal error */
+               rc = 0;
+               goto err_no_driver;
+       }
+
        /* Get children of this key */
        if ( ( rc = xenstore_directory ( xen, &children, &len, "device",
                                         type, NULL ) ) != 0 ) {
@@ -326,8 +328,8 @@ static int xenbus_probe_type ( struct xen_hypervisor *xen,
        /* Probe each child */
        for ( child = children ; child < ( children + len ) ;
              child += ( strlen ( child ) + 1 /* NUL */ ) ) {
-               if ( ( rc = xenbus_probe_device ( xen, parent, type,
-                                                 child ) ) != 0 )
+               if ( ( rc = xenbus_probe_device ( xen, parent, child,
+                                                 driver ) ) != 0 )
                        goto err_probe_device;
        }
 
@@ -337,6 +339,7 @@ static int xenbus_probe_type ( struct xen_hypervisor *xen,
  err_probe_device:
        free ( children );
  err_directory:
+ err_no_driver:
        return rc;
 }