Re: [PATCH mm] sysfs: add /sys/dev/usb to handle CONFIG_USB_DEVICE_CLASS=y

From: Dan Williams
Date: Thu Apr 17 2008 - 23:44:36 EST


On Thu, Apr 17, 2008 at 8:08 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, 17 Apr 2008 19:11:03 -0700 Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
> > The deprecated config option CONFIG_USB_DEVICE_CLASS causes class devices
> > with duplicate major:minor numbers to be registered. In effect they
> > represent a usb specific address space for major:minor numbers so add 'usb'
> > as a directory along side 'block' and 'char'.
> >
>
> hm. That's a somewhat nasty patch you have there.
>

Yeah, it was a frantic unbreak -mm attempt more than anything else :(.

>
> >
> > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > index ba21118..bce5e4b 100644
> > --- a/drivers/base/core.c
> > +++ b/drivers/base/core.c
> > @@ -30,6 +30,10 @@ int (*platform_notify_remove)(struct device *dev) = NULL;
> > static struct kobject *dev_kobj;
> > static struct kobject *char_kobj;
> > static struct kobject *block_kobj;
> > +#ifdef CONFIG_USB_DEVICE_CLASS
> > +extern struct class *usb_classdev_class;
>
> This should be in a header file, but where?
>
>
> > +static struct kobject *usb_kobj;
> > +#endif
> >
> > #ifdef CONFIG_BLOCK
> > static inline int device_is_not_partition(struct device *dev)
> > @@ -764,7 +768,13 @@ static void device_remove_class_symlinks(struct device *dev)
> >
> > static struct kobject *device_to_dev_kobj(struct device *dev)
> > {
> > - return dev->class == &block_class ? block_kobj : char_kobj;
> > + if (dev->class == &block_class)
> > + return block_kobj;
>
> Does the existing code compile-n-work with CONFIG_BLOCK=n?
>

I'll take a look. And Greg shares my suspicion that there might be
other duplicate devices like these USB class devices, so need to look
for that as well.

>
> > +#ifdef CONFIG_USB_DEVICE_CLASS
> > + if (usb_classdev_class && dev->class == usb_classdev_class)
> > + return usb_kobj;
> > +#endif
>
> > +#ifdef CONFIG_USB_DEVICE_CLASS
> > + usb_kobj = kobject_create_and_add("usb", dev_kobj);
> > + if (!usb_kobj)
> > + goto usb_kobj_err;
> > +#endif
>
> > +#ifdef CONFIG_USB_DEVICE_CLASS
> > + usb_kobj_err:
> > + kobject_put(char_kobj);
> > +#endif
>
> > +#ifdef CONFIG_USB_DEVICE_CLASS
> > + kobject_put(usb_kobj);
> > +#endif
>
> mutter. I'd have thought that with suitable fiddling most of this code
> could be moved into the USB core and some of it (the
> kobject_create_and_add()) can be done via USB's initcalls.
>
> this:
>
> --- a/drivers/base/core.c~sysfs-add-sys-dev-usb-to-handle-config_usb_device_class=y-fix
> +++ a/drivers/base/core.c
> @@ -31,7 +31,6 @@ static struct kobject *dev_kobj;
>
> static struct kobject *char_kobj;
> static struct kobject *block_kobj;
> #ifdef CONFIG_USB_DEVICE_CLASS
> -extern struct class *usb_classdev_class;
> static struct kobject *usb_kobj;
> #endif
>
> diff -puN drivers/usb/core/devio.c~sysfs-add-sys-dev-usb-to-handle-config_usb_device_class=y-fix drivers/usb/core/devio.c
> --- a/drivers/usb/core/devio.c~sysfs-add-sys-dev-usb-to-handle-config_usb_device_class=y-fix
> +++ a/drivers/usb/core/devio.c
> @@ -43,6 +43,7 @@
> #include <linux/signal.h>
> #include <linux/poll.h>
> #include <linux/module.h>
> +#include <linux/device.h>
> #include <linux/usb.h>
> #include <linux/usbdevice_fs.h>
> #include <linux/cdev.h>
> diff -puN include/linux/device.h~sysfs-add-sys-dev-usb-to-handle-config_usb_device_class=y-fix include/linux/device.h
> --- a/include/linux/device.h~sysfs-add-sys-dev-usb-to-handle-config_usb_device_class=y-fix
> +++ a/include/linux/device.h
> @@ -623,4 +623,6 @@ extern const char *dev_driver_string(str
> #define MODULE_ALIAS_CHARDEV_MAJOR(major) \
> MODULE_ALIAS("char-major-" __stringify(major) "-*")
>
>
> +extern struct class *usb_classdev_class;
> +
> #endif /* _DEVICE_H_ */
> _
>
> deworsens things slightly.
>

Thanks,
Dan
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