Xen: consolidate and simplify struct xenbus_driver instantiation

The 'name', 'owner', and 'mod_name' members are redundant with the
identically named fields in the 'driver' sub-structure. Rather than
switching each instance to specify these fields explicitly, introduce
a macro to simplify this.

Eliminate further redundancy by allowing the drvname argument to
DEFINE_XENBUS_DRIVER() to be blank (in which case the first entry from
the ID table will be used for .driver.name).

Also eliminate the questionable xenbus_register_{back,front}end()
wrappers - their sole remaining purpose was the checking of the
'owner' field, proper setting of which shouldn't be an issue anymore
when the macro gets used.

v2: Restore DRV_NAME for the driver name in xen-pciback.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 9 insertions, 22 deletions

diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index b1b6676c1c4..e8c599b237c 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -85,8 +85,6 @@ struct xenbus_device_id
 
 /* A xenbus driver. */
 struct xenbus_driver {
-	char *name;
-	struct module *owner;
 	const struct xenbus_device_id *ids;
 	int (*probe)(struct xenbus_device *dev,
 		     const struct xenbus_device_id *id);
@@ -101,31 +99,20 @@ struct xenbus_driver {
 	int (*is_ready)(struct xenbus_device *dev);
 };
 
-static inline struct xenbus_driver *to_xenbus_driver(struct device_driver *drv)
-{
-	return container_of(drv, struct xenbus_driver, driver);
+#define DEFINE_XENBUS_DRIVER(var, drvname, methods...)		\
+struct xenbus_driver var ## _driver = {				\
+	.driver.name = drvname + 0 ?: var ## _ids->devicetype,	\
+	.driver.owner = THIS_MODULE,				\
+	.ids = var ## _ids, ## methods				\
 }
 
-int __must_check __xenbus_register_frontend(struct xenbus_driver *drv,
-					    struct module *owner,
-					    const char *mod_name);
-
-static inline int __must_check
-xenbus_register_frontend(struct xenbus_driver *drv)
+static inline struct xenbus_driver *to_xenbus_driver(struct device_driver *drv)
 {
-	WARN_ON(drv->owner != THIS_MODULE);
-	return __xenbus_register_frontend(drv, THIS_MODULE, KBUILD_MODNAME);
+	return container_of(drv, struct xenbus_driver, driver);
 }
 
-int __must_check __xenbus_register_backend(struct xenbus_driver *drv,
-					   struct module *owner,
-					   const char *mod_name);
-static inline int __must_check
-xenbus_register_backend(struct xenbus_driver *drv)
-{
-	WARN_ON(drv->owner != THIS_MODULE);
-	return __xenbus_register_backend(drv, THIS_MODULE, KBUILD_MODNAME);
-}
+int __must_check xenbus_register_frontend(struct xenbus_driver *);
+int __must_check xenbus_register_backend(struct xenbus_driver *);
 
 void xenbus_unregister_driver(struct xenbus_driver *drv);