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SubjectRe: [PATCH] Xen: consolidate and simplify struct xenbus_driver instantiation
On Wed, Dec 21, 2011 at 04:01:27PM +0000, Jan Beulich wrote:
> 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.

Looks good, except:

a) It also needs four ACKs from:

1) block for block maintainer (Jens Axboe <axboe@kernel.dk> )
2) kbdinput for input maintainer (Dmitry Torokhov <dmitry.torokhov@gmail.com)
3) fbfront for the video maintainer (FlorianSchandinat@gmx.de)
4) network for the network maintainer (Ian Campbell <ian.campbell@citrix.com>, netdev@vger.kernel.org ,"David S. Miller" <davem@davemloft.net>)

CC-ing all of them.

b) this is changing it from xen-pciback to pciback:

> --- 3.2-rc6/drivers/xen/xen-pciback/xenbus.c
> +++ 3.2-rc6-struct-xenbus_driver/drivers/xen/xen-pciback/xenbus.c
> @@ -707,19 +707,16 @@ static int xen_pcibk_xenbus_remove(struc
> 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, "pciback",
^^^^^^^^^
I think that should be "xen-pciback" or just DRV_NAME ?

> .probe = xen_pcibk_xenbus_probe,
> .remove = xen_pcibk_xenbus_remove,
> .otherend_changed = xen_pcibk_frontend_changed,
> -};
> +);

Otherwise all the other changes look OK to me.

Here is the unchanged version of the patch for the other maintainers.

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.
Signed-off-by: Jan Beulich <jbeulich@suse.com>

---
drivers/block/xen-blkback/xenbus.c | 9 ++------
drivers/block/xen-blkfront.c | 11 +++-------
drivers/input/misc/xen-kbdfront.c | 7 +-----
drivers/net/xen-netback/xenbus.c | 9 ++------
drivers/net/xen-netfront.c | 9 ++------
drivers/pci/xen-pcifront.c | 11 +++-------
drivers/video/xen-fbfront.c | 9 ++------
drivers/xen/xen-pciback/xenbus.c | 13 ++++--------
drivers/xen/xenbus/xenbus_probe.c | 7 ------
drivers/xen/xenbus/xenbus_probe.h | 4 ---
drivers/xen/xenbus/xenbus_probe_backend.c | 8 ++-----
drivers/xen/xenbus/xenbus_probe_frontend.c | 8 ++-----
include/xen/xenbus.h | 31 ++++++++---------------------
13 files changed, 44 insertions(+), 92 deletions(-)
--- 3.2-rc6/drivers/block/xen-blkback/xenbus.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/block/xen-blkback/xenbus.c
@@ -787,17 +787,14 @@ static const struct xenbus_device_id xen
};


-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);
}
--- 3.2-rc6/drivers/block/xen-blkfront.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/block/xen-blkfront.c
@@ -1437,16 +1437,13 @@ static const struct xenbus_device_id blk
{ "" }
};

-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);

--- 3.2-rc6/drivers/input/misc/xen-kbdfront.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/input/misc/xen-kbdfront.c
@@ -361,15 +361,12 @@ static const struct xenbus_device_id xen
{ "" }
};

-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)
{
--- 3.2-rc6/drivers/net/xen-netback/xenbus.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/net/xen-netback/xenbus.c
@@ -474,17 +474,14 @@ static const struct xenbus_device_id net
};


-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);
}
--- 3.2-rc6/drivers/net/xen-netfront.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/net/xen-netfront.c
@@ -1910,7 +1910,7 @@ static void xennet_sysfs_delif(struct ne

#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(struc
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)
{
--- 3.2-rc6/drivers/pci/xen-pcifront.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/pci/xen-pcifront.c
@@ -1126,14 +1126,11 @@ static const struct xenbus_device_id xen
{""},
};

-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);
--- 3.2-rc6/drivers/video/xen-fbfront.c
+++ 3.2-rc6-struct-xenbus_driver/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)
{
--- 3.2-rc6/drivers/xen/xen-pciback/xenbus.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/xen/xen-pciback/xenbus.c
@@ -707,19 +707,16 @@ static int xen_pcibk_xenbus_remove(struc
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, "pciback",
.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(voi
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);
}
--- 3.2-rc6/drivers/xen/xenbus/xenbus_probe.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/xen/xenbus/xenbus_probe.c
@@ -291,14 +291,9 @@ void xenbus_dev_shutdown(struct device *
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);
}
--- 3.2-rc6/drivers/xen/xenbus/xenbus_probe.h
+++ 3.2-rc6-struct-xenbus_driver/drivers/xen/xenbus/xenbus_probe.h
@@ -53,9 +53,7 @@ extern int xenbus_match(struct device *_
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);
--- 3.2-rc6/drivers/xen/xenbus/xenbus_probe_backend.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -232,15 +232,13 @@ int xenbus_dev_is_online(struct xenbus_d
}
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,
--- 3.2-rc6/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ 3.2-rc6-struct-xenbus_driver/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -230,15 +230,13 @@ static void wait_for_devices(struct xenb
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 xe

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;
--- 3.2-rc6/include/xen/xenbus.h
+++ 3.2-rc6-struct-xenbus_driver/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);


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