[PARCH] driver core: add driver_find to find a driver by name

[PARCH] driver core: add driver_find to find a driver by name

[Dmitry Torokhov]

Hi,

Here is a patch that adds driver_find() that allows to search for a driver
on a bus by it's name. The function is similar to device_find already present
in the tree. I need it for my serio sysfs patches where user can re-bind
serio port to an alternate driver by echoing driver's name to serio port's
driver attribute.

-- 
Dmitry


===================================================================


ChangeSet@1.1792, 2004-06-27 20:49:01-05:00, dtor_core@ameritech.net
  Driver core: add driver_find helper to find a driver by its name
  
  Signed-off-by: Dmitry Torokhov <dtor@mail.ru>


 drivers/base/driver.c  |   16 ++++++++++++++++
 include/linux/device.h |    1 +
 2 files changed, 17 insertions(+)


===================================================================



diff -Nru a/drivers/base/driver.c b/drivers/base/driver.c
--- a/drivers/base/driver.c	2004-06-27 21:24:06 -05:00
+++ b/drivers/base/driver.c	2004-06-27 21:24:06 -05:00
@@ -111,10 +111,26 @@
 	up(&drv->unload_sem);
 }
 
+/**
+ *	driver_find - find driver on a given bus by its name.
+ *	@name:	name of the driver.
+ *	@bus:	bus to seatch for the driver
+ */
+
+struct device_driver *driver_find(const char *name, struct bus_type *bus)
+{
+	struct kobject *k = kset_find_obj(&bus->drivers, name);
+	if (k)
+		return to_drv(k);
+	return NULL;
+}
+
+
 EXPORT_SYMBOL(driver_register);
 EXPORT_SYMBOL(driver_unregister);
 EXPORT_SYMBOL(get_driver);
 EXPORT_SYMBOL(put_driver);
+EXPORT_SYMBOL(driver_find);
 
 EXPORT_SYMBOL(driver_create_file);
 EXPORT_SYMBOL(driver_remove_file);
diff -Nru a/include/linux/device.h b/include/linux/device.h
--- a/include/linux/device.h	2004-06-27 21:24:06 -05:00
+++ b/include/linux/device.h	2004-06-27 21:24:06 -05:00
@@ -120,6 +120,7 @@
 
 extern struct device_driver * get_driver(struct device_driver * drv);
 extern void put_driver(struct device_driver * drv);
+extern struct device_driver *driver_find(const char *name, struct bus_type *bus);
 
 
 /* driverfs interface for exporting driver attributes */

Re: [PARCH] driver core: add driver_find to find a driver by name

[Christoph Hellwig]

On Sun, Jun 27, 2004 at 09:26:03PM -0500, Dmitry Torokhov wrote:
> Hi,
> 
> Here is a patch that adds driver_find() that allows to search for a driver
> on a bus by it's name. The function is similar to device_find already present
> in the tree. I need it for my serio sysfs patches where user can re-bind
> serio port to an alternate driver by echoing driver's name to serio port's
> driver attribute.

It looks like it's missing some refcounting, no?

RE: [PARCH] driver core: add driver_find to find a driver by name

[Dmitry Torokhov]

Christoph Hellwig wrote:
> On Sun, Jun 27, 2004 at 09:26:03PM -0500, Dmitry Torokhov wrote:
> > Hi,
> >
> > Here is a patch that adds driver_find() that allows to search for a
> driver
> > on a bus by it's name. The function is similar to device_find already
> present
> > in the tree. I need it for my serio sysfs patches where user can re-bind
> > serio port to an alternate driver by echoing driver's name to serio
> port's
> > driver attribute.
> 
> It looks like it's missing some refcounting, no?

Actually I think that kset_find_obj is the one that is missing
refcounting - device/driver can easily go away on return from
this function as well, no?

Anyway, usage in serio should be fine as the whole thing is
protected by serio_sem.

--
Dmitry

Re: [PARCH] driver core: add driver_find to find a driver by name

[Greg KH]

On Sun, Jun 27, 2004 at 09:26:03PM -0500, Dmitry Torokhov wrote:
> Hi,
> 
> Here is a patch that adds driver_find() that allows to search for a driver
> on a bus by it's name. The function is similar to device_find already present
> in the tree. I need it for my serio sysfs patches where user can re-bind
> serio port to an alternate driver by echoing driver's name to serio port's
> driver attribute.

Applied, thanks.

greg k-h

Re: [PARCH] driver core: add driver_find to find a driver by name

[Marcelo Tosatti]

On Wed, Jul 14, 2004 at 04:02:46PM -0700, Greg KH wrote:
> On Sun, Jun 27, 2004 at 09:26:03PM -0500, Dmitry Torokhov wrote:
> > Hi,
> > 
> > Here is a patch that adds driver_find() that allows to search for a driver
> > on a bus by it's name. The function is similar to device_find already present
> > in the tree. I need it for my serio sysfs patches where user can re-bind
> > serio port to an alternate driver by echoing driver's name to serio port's
> > driver attribute.
> 
> Applied, thanks.

Dmitry,

I remember you fixed kset_find_obj() to get a reference count on the kobject.

driver_find()/device_find() use that, maybe it would be nice to add a comment 
on top of those saying the caller is responsible for putting the refcount 
on the kobject?

Last time I looked at your patches there was no such comment on driver_find/device_find, 
only kset_find_obj().

Just nitpicking.

Re: [PARCH] driver core: add driver_find to find a driver by name

[Dmitry Torokhov]

On Thursday 15 July 2004 07:30 am, Marcelo Tosatti wrote:
> On Wed, Jul 14, 2004 at 04:02:46PM -0700, Greg KH wrote:
> > On Sun, Jun 27, 2004 at 09:26:03PM -0500, Dmitry Torokhov wrote:
> > > Hi,
> > > 
> > > Here is a patch that adds driver_find() that allows to search for a driver
> > > on a bus by it's name. The function is similar to device_find already present
> > > in the tree. I need it for my serio sysfs patches where user can re-bind
> > > serio port to an alternate driver by echoing driver's name to serio port's
> > > driver attribute.
> > 
> > Applied, thanks.
> 
> Dmitry,
> 
> I remember you fixed kset_find_obj() to get a reference count on the kobject.
> 
> driver_find()/device_find() use that, maybe it would be nice to add a comment 
> on top of those saying the caller is responsible for putting the refcount 
> on the kobject?
> 
> Last time I looked at your patches there was no such comment on driver_find/device_find, 
> only kset_find_obj().
> 
> Just nitpicking.
> 

Hi Marcelo,

I tried to document driver_find, device_find and find_bus, please check out
the version that Greg has committed. If comments still somewhat unclear I
will try redoing them.

-- 
Dmitry