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>

13 files changed, 44 insertions, 92 deletions

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index f759ad4584c3..edbb69ebdf20 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -787,17 +787,14 @@ static const struct xenbus_device_id xen_blkbk_ids[] = {
 };
 
 
-static struct xenbus_driver xen_blkbk = {
-        .name = "vbd",
-        .owner = THIS_MODULE,
-        .ids = xen_blkbk_ids,
+static DEFINE_XENBUS_DRIVER(xen_blkbk, ,
         .probe = xen_blkbk_probe,
         .remove = xen_blkbk_remove,
         .otherend_changed = frontend_changed
-};
+);
 
 
 int xen_blkif_xenbus_init(void)
 {
-        return xenbus_register_backend(&xen_blkbk);
+        return xenbus_register_backend(&xen_blkbk_driver);
 }
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 7b2ec5908413..9fd3ee203b1e 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1437,16 +1437,13 @@ static const struct xenbus_device_id blkfront_ids[] = {
         { "" }
 };
 
-static struct xenbus_driver blkfront = {
-        .name = "vbd",
-        .owner = THIS_MODULE,
-        .ids = blkfront_ids,
+static DEFINE_XENBUS_DRIVER(blkfront, ,
         .probe = blkfront_probe,
         .remove = blkfront_remove,
         .resume = blkfront_resume,
         .otherend_changed = blkback_changed,
         .is_ready = blkfront_is_ready,
-};
+);
 
 static int __init xlblk_init(void)
 {
@@ -1461,7 +1458,7 @@ static int __init xlblk_init(void)
                 return -ENODEV;
         }
 
-        ret = xenbus_register_frontend(&blkfront);
+        ret = xenbus_register_frontend(&blkfront_driver);
         if (ret) {
                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
                 return ret;
@@ -1474,7 +1471,7 @@ module_init(xlblk_init);
 
 static void __exit xlblk_exit(void)
 {
-        return xenbus_unregister_driver(&blkfront);
+        return xenbus_unregister_driver(&blkfront_driver);
 }
 module_exit(xlblk_exit);
 
diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
index ad2e51c04db8..02ca8680ea5b 100644
--- a/drivers/input/misc/xen-kbdfront.c
+++ b/drivers/input/misc/xen-kbdfront.c
@@ -361,15 +361,12 @@ static const struct xenbus_device_id xenkbd_ids[] = {
         { "" }
 };
 
-static struct xenbus_driver xenkbd_driver = {
-        .name = "vkbd",
-        .owner = THIS_MODULE,
-        .ids = xenkbd_ids,
+static DEFINE_XENBUS_DRIVER(xenkbd, ,
         .probe = xenkbd_probe,
         .remove = xenkbd_remove,
         .resume = xenkbd_resume,
         .otherend_changed = xenkbd_backend_changed,
-};
+);
 
 static int __init xenkbd_init(void)
 {
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 1ce729d6af75..410018c4c528 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -474,17 +474,14 @@ static const struct xenbus_device_id netback_ids[] = {
 };
 
 
-static struct xenbus_driver netback = {
-        .name = "vif",
-        .owner = THIS_MODULE,
-        .ids = netback_ids,
+static DEFINE_XENBUS_DRIVER(netback, ,
         .probe = netback_probe,
         .remove = netback_remove,
         .uevent = netback_uevent,
         .otherend_changed = frontend_changed,
-};
+);
 
 int xenvif_xenbus_init(void)
 {
-        return xenbus_register_backend(&netback);
+        return xenbus_register_backend(&netback_driver);
 }
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 226faab23603..81ff5a749279 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1910,7 +1910,7 @@ static void xennet_sysfs_delif(struct net_device *netdev)
 
 #endif /* CONFIG_SYSFS */
 
-static struct xenbus_device_id netfront_ids[] = {
+static const struct xenbus_device_id netfront_ids[] = {
         { "vif" },
         { "" }
 };
@@ -1937,15 +1937,12 @@ static int __devexit xennet_remove(struct xenbus_device *dev)
         return 0;
 }
 
-static struct xenbus_driver netfront_driver = {
-        .name = "vif",
-        .owner = THIS_MODULE,
-        .ids = netfront_ids,
+static DEFINE_XENBUS_DRIVER(netfront, ,
         .probe = netfront_probe,
         .remove = __devexit_p(xennet_remove),
         .resume = netfront_resume,
         .otherend_changed = netback_changed,
-};
+);
 
 static int __init netif_init(void)
 {
diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 90832a955991..7cf3d2fcf56a 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -1126,14 +1126,11 @@ static const struct xenbus_device_id xenpci_ids[] = {
         {""},
 };
 
-static struct xenbus_driver xenbus_pcifront_driver = {
-        .name                   = "pcifront",
-        .owner                  = THIS_MODULE,
-        .ids                    = xenpci_ids,
+static DEFINE_XENBUS_DRIVER(xenpci, "pcifront",
         .probe                  = pcifront_xenbus_probe,
         .remove                 = pcifront_xenbus_remove,
         .otherend_changed       = pcifront_backend_changed,
-};
+);
 
 static int __init pcifront_init(void)
 {
@@ -1142,12 +1139,12 @@ static int __init pcifront_init(void)
 
         pci_frontend_registrar(1 /* enable */);
 
-        return xenbus_register_frontend(&xenbus_pcifront_driver);
+        return xenbus_register_frontend(&xenpci_driver);
 }
 
 static void __exit pcifront_cleanup(void)
 {
-        xenbus_unregister_driver(&xenbus_pcifront_driver);
+        xenbus_unregister_driver(&xenpci_driver);
         pci_frontend_registrar(0 /* disable */);
 }
 module_init(pcifront_init);
diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
index beac52fc1c0e..cb4529c40d74 100644
--- a/drivers/video/xen-fbfront.c
+++ b/drivers/video/xen-fbfront.c
@@ -671,20 +671,17 @@ InitWait:
         }
 }
 
-static struct xenbus_device_id xenfb_ids[] = {
+static const struct xenbus_device_id xenfb_ids[] = {
         { "vfb" },
         { "" }
 };
 
-static struct xenbus_driver xenfb_driver = {
-        .name = "vfb",
-        .owner = THIS_MODULE,
-        .ids = xenfb_ids,
+static DEFINE_XENBUS_DRIVER(xenfb, ,
         .probe = xenfb_probe,
         .remove = xenfb_remove,
         .resume = xenfb_resume,
         .otherend_changed = xenfb_backend_changed,
-};
+);
 
 static int __init xenfb_init(void)
 {
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index 075525945e36..c80f9c84d08e 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -707,19 +707,16 @@ static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
         return 0;
 }
 
-static const struct xenbus_device_id xenpci_ids[] = {
+static const struct xenbus_device_id xen_pcibk_ids[] = {
         {"pci"},
         {""},
 };
 
-static struct xenbus_driver xenbus_xen_pcibk_driver = {
-        .name                   = DRV_NAME,
-        .owner                  = THIS_MODULE,
-        .ids                    = xenpci_ids,
+static DEFINE_XENBUS_DRIVER(xen_pcibk, DRV_NAME,
         .probe                  = xen_pcibk_xenbus_probe,
         .remove                 = xen_pcibk_xenbus_remove,
         .otherend_changed       = xen_pcibk_frontend_changed,
-};
+);
 
 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 
@@ -735,11 +732,11 @@ int __init xen_pcibk_xenbus_register(void)
         if (passthrough)
                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
         pr_info(DRV_NAME ": backend is %s\n", xen_pcibk_backend->name);
-        return xenbus_register_backend(&xenbus_xen_pcibk_driver);
+        return xenbus_register_backend(&xen_pcibk_driver);
 }
 
 void __exit xen_pcibk_xenbus_unregister(void)
 {
         destroy_workqueue(xen_pcibk_wq);
-        xenbus_unregister_driver(&xenbus_xen_pcibk_driver);
+        xenbus_unregister_driver(&xen_pcibk_driver);
 }
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 1c05b2508ae8..3864967202b5 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -291,14 +291,9 @@ void xenbus_dev_shutdown(struct device *_dev)
 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 
 int xenbus_register_driver_common(struct xenbus_driver *drv,
-                                  struct xen_bus_type *bus,
-                                  struct module *owner,
-                                  const char *mod_name)
+                                  struct xen_bus_type *bus)
 {
-        drv->driver.name = drv->name;
         drv->driver.bus = &bus->bus;
-        drv->driver.owner = owner;
-        drv->driver.mod_name = mod_name;
 
         return driver_register(&drv->driver);
 }
diff --git a/drivers/xen/xenbus/xenbus_probe.h b/drivers/xen/xenbus/xenbus_probe.h
index 460d784a769a..bb4f92ed8730 100644
--- a/drivers/xen/xenbus/xenbus_probe.h
+++ b/drivers/xen/xenbus/xenbus_probe.h
@@ -53,9 +53,7 @@ extern int xenbus_match(struct device *_dev, struct device_driver *_drv);
 extern int xenbus_dev_probe(struct device *_dev);
 extern int xenbus_dev_remove(struct device *_dev);
 extern int xenbus_register_driver_common(struct xenbus_driver *drv,
-                                         struct xen_bus_type *bus,
-                                         struct module *owner,
-                                         const char *mod_name);
+                                         struct xen_bus_type *bus);
 extern int xenbus_probe_node(struct xen_bus_type *bus,
                              const char *type,
                              const char *nodename);
diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c
index c3c7cd195c11..257be37d9091 100644
--- a/drivers/xen/xenbus/xenbus_probe_backend.c
+++ b/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -232,15 +232,13 @@ int xenbus_dev_is_online(struct xenbus_device *dev)
 }
 EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
 
-int __xenbus_register_backend(struct xenbus_driver *drv,
-                              struct module *owner, const char *mod_name)
+int xenbus_register_backend(struct xenbus_driver *drv)
 {
         drv->read_otherend_details = read_frontend_details;
 
-        return xenbus_register_driver_common(drv, &xenbus_backend,
-                                             owner, mod_name);
+        return xenbus_register_driver_common(drv, &xenbus_backend);
 }
-EXPORT_SYMBOL_GPL(__xenbus_register_backend);
+EXPORT_SYMBOL_GPL(xenbus_register_backend);
 
 static int backend_probe_and_watch(struct notifier_block *notifier,
                                    unsigned long event,
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index 2f73195512b4..9c57819df51a 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -230,15 +230,13 @@ static void wait_for_devices(struct xenbus_driver *xendrv)
                          print_device_status);
 }
 
-int __xenbus_register_frontend(struct xenbus_driver *drv,
-                               struct module *owner, const char *mod_name)
+int xenbus_register_frontend(struct xenbus_driver *drv)
 {
         int ret;
 
         drv->read_otherend_details = read_backend_details;
 
-        ret = xenbus_register_driver_common(drv, &xenbus_frontend,
-                                            owner, mod_name);
+        ret = xenbus_register_driver_common(drv, &xenbus_frontend);
         if (ret)
                 return ret;
 
@@ -247,7 +245,7 @@ int __xenbus_register_frontend(struct xenbus_driver *drv,
 
         return 0;
 }
-EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
+EXPORT_SYMBOL_GPL(xenbus_register_frontend);
 
 static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
 static int backend_state;
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index b1b6676c1c43..e8c599b237c2 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);