A parent-less device should not crash dahdi

* A parent-less device should not crash dahdi:
  - Access span->parent->dev instead of span->parent-dev.parent
    in soem cases.
  - Access span->parent->dev via new inline span_device()
  - Use span_device() in all dahdi_dev_{dbg,info}()

* Allow low-level drivers to set their device name.
  - Drivers that don't use this feature get the default name
    based on the parent device name
  - Parent-less devices which don't set their name, fails
    to register with -EINVAL

Signed-off-by: Oron Peled <oron.peled@xorcom.com>
Acked-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>

Origin: http://svnview.digium.com/svn/dahdi?view=rev&rev=10449

git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/branches/2.6@10568 a0bf4364-ded3-4de4-8d8a-66a801d63aff

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/dahdi/dahdi-sysfs.c b/drivers/dahdi/dahdi-sysfs.c
index a03aba8..3e6d157 100644
--- a/drivers/dahdi/dahdi-sysfs.c
+++ b/drivers/dahdi/dahdi-sysfs.c
@@ -796,10 +796,17 @@ int dahdi_sysfs_add_device(struct dahdi_device *ddev, struct device *parent)
 {
 	int ret;
 	struct device *const dev = &ddev->dev;
+	const char *dn;
 
 	dev->parent = parent;
 	dev->bus = &dahdi_device_bus;
-	dev_set_name(dev, "%s:%s", parent->bus->name, dev_name(parent));
+	dn = dev_name(dev);
+	if (!dn || !*dn) {
+		/* Invent default name based on parent */
+		if (!parent)
+			return -EINVAL;
+		dev_set_name(dev, "%s:%s", parent->bus->name, dev_name(parent));
+	}
 	ret = device_add(dev);
 	return ret;
 }