[patch] detect duplicate drivers

[Stas Sergeev]

Hello.

Currently an attempt to register multiple
drivers with the same name causes the
stack trace with some cryptic error message.
The attached patch adds the necessary check
and the clear error message.

Signed-off-by: Stas Sergeev <stsp@xxxxxxxx>
--- a/drivers/base/driver.c	2008-04-22 20:51:31.000000000 +0400
+++ b/drivers/base/driver.c	2008-04-26 19:43:26.000000000 +0400
@@ -217,12 +217,22 @@
 int driver_register(struct device_driver *drv)
 {
 	int ret;
+	struct device_driver *other;
 
 	if ((drv->bus->probe && drv->probe) ||
 	    (drv->bus->remove && drv->remove) ||
 	    (drv->bus->shutdown && drv->shutdown))
 		printk(KERN_WARNING "Driver '%s' needs updating - please use "
 			"bus_type methods\n", drv->name);
+
+	other = driver_find(drv->name, drv->bus);
+	if (other) {
+		put_driver(other);
+		printk(KERN_ERR "Error: Driver '%s' is already registered, "
+			"aborting...\n", drv->name);
+		return -EEXIST;
+	}
+
 	ret = bus_add_driver(drv);
 	if (ret)
 		return ret;