Re: [patch] convert the scsi layer to use struct device

Kay Sievers
2008-03-15T18:25:54Z

On Sat, 2008-03-15 at 13:01 -0500, James Bottomley wrote:
> On Sat, 2008-03-15 at 11:16 -0500, James Bottomley wrote:
> > On Sat, 2008-03-15 at 16:17 +0100, Kay Sievers wrote:
> > > We just need to create something like a "contains" link from the
> > > component to the scsi device, and a "enclosure" link at the scsi device
> > > back to the component, right?
> >
> > Assuming you're moving to the single tree model, then I can easily do
> > this:
> >
> > <real enclosure device>/<enclosure>/<enclosure component>/device -> link
> > to component device
> >
> > with a back link in the component device pointing to the enclosure
> > component.
> >
> > The way components work, probably blowing away enclosure_component_class
> > makes the most sense anyway.
>
> OK, so this is the patch doing the above; is this what you had in mind?
> We're now managing all the links.

Yeah, that looks fine.

While I in general don't really like the <classname>:<devname> symlinks.
One needs to readdir() the whole device directory to find them, which is
not nice for a 1:1 relationship link between two devices. I would prefer
to be able to find an enclosure component for a LUN by simply looking
at:
/sys/bus/scsi/devices/0:0:0:0/enclosure/
instead of searching for that composed link, because one can't predict
its name. Can there ever be more than one link from a device to an
enclosure?

Also the "device" link, it will work to use that name, I guess, but it
has usually a different meaning, as all "device" links are just
meaninglessly pointing to the next parent device with !SYSFS_DEPRECATED.
﻿With !SYSFS_DEPRECATED <classname>:<devname> links are no longer
created for any device, the class device directories just live in a
subdirectory with the class name.

Do you prefer the <classname>:<devname>, "device" names?

Thanks,
Kay

> diff --git a/drivers/misc/enclosure.c b/drivers/misc/enclosure.c
> index fafb57f..0736cff 100644
> --- a/drivers/misc/enclosure.c
> +++ b/drivers/misc/enclosure.c
> @@ -31,7 +31,6 @@
> static LIST_HEAD(container_list);
> static DEFINE_MUTEX(container_list_lock);
> static struct class enclosure_class;
> -static struct class enclosure_component_class;
>
> /**
> * enclosure_find - find an enclosure given a device
> @@ -166,6 +165,40 @@ void enclosure_unregister(struct enclosure_device *edev)
> }
> EXPORT_SYMBOL_GPL(enclosure_unregister);
>
> +#define ENCLOSURE_NAME_SIZE 64
> +
> +static void enclosure_link_name(struct enclosure_component *cdev, char *name)
> +{
> + strcpy(name, "enclosure_device:");
> + strcat(name, cdev->cdev.bus_id);
> +}
> +
> +static void enclosure_remove_links(struct enclosure_component *cdev)
> +{
> + char name[ENCLOSURE_NAME_SIZE];
> +
> + enclosure_link_name(cdev, name);
> + sysfs_remove_link(&cdev->dev->kobj, name);
> + sysfs_remove_link(&cdev->cdev.kobj, "device");
> +}
> +
> +static int enclosure_add_links(struct enclosure_component *cdev)
> +{
> + int error;
> + char name[ENCLOSURE_NAME_SIZE];
> +
> + error = sysfs_create_link(&cdev->cdev.kobj, &cdev->dev->kobj, "device");
> + if (error)
> + return error;
> +
> + enclosure_link_name(cdev, name);
> + error = sysfs_create_link(&cdev->dev->kobj, &cdev->cdev.kobj, name);
> + if (error)
> + sysfs_remove_link(&cdev->cdev.kobj, "device");
> +
> + return error;
> +}
> +
> static void enclosure_release(struct device *cdev)
> {
> struct enclosure_device *edev = to_enclosure_device(cdev);
> @@ -178,10 +211,15 @@ static void enclosure_component_release(struct device *dev)
> {
> struct enclosure_component *cdev = to_enclosure_component(dev);
>
> - put_device(cdev->dev);
> + if (cdev->dev) {
> + enclosure_remove_links(cdev);
> + put_device(cdev->dev);
> + }
> put_device(dev->parent);
> }
>
> +static struct attribute_group *enclosure_groups[];
> +
> /**
> * enclosure_component_register - add a particular component to an enclosure
> * @edev: the enclosure to add the component
> @@ -217,12 +255,14 @@ enclosure_component_register(struct enclosure_device *edev,
> ecomp->number = number;
> cdev = &ecomp->cdev;
> cdev->parent = get_device(&edev->edev);
> - cdev->class = &enclosure_component_class;
> if (name)
> snprintf(cdev->bus_id, BUS_ID_SIZE, "%s", name);
> else
> snprintf(cdev->bus_id, BUS_ID_SIZE, "%u", number);
>
> + cdev->release = enclosure_component_release;
> + cdev->groups = enclosure_groups;
> +
> err = device_register(cdev);
> if (err)
> ERR_PTR(err);
> @@ -255,10 +295,12 @@ int enclosure_add_device(struct enclosure_device *edev, int component,
>
> cdev = &edev->component[component];
>
> - device_del(&cdev->cdev);
> + if (cdev->dev)
> + enclosure_remove_links(cdev);
> +
> put_device(cdev->dev);
> cdev->dev = get_device(dev);
> - return device_add(&cdev->cdev);
> + return enclosure_add_links(cdev);
> }
> EXPORT_SYMBOL_GPL(enclosure_add_device);
>
> @@ -442,24 +484,32 @@ static ssize_t get_component_type(struct device *cdev,
> }
>
>
> -static struct device_attribute enclosure_component_attrs[] = {
> - __ATTR(fault, S_IRUGO | S_IWUSR, get_component_fault,
> - set_component_fault),
> - __ATTR(status, S_IRUGO | S_IWUSR, get_component_status,
> - set_component_status),
> - __ATTR(active, S_IRUGO | S_IWUSR, get_component_active,
> - set_component_active),
> - __ATTR(locate, S_IRUGO | S_IWUSR, get_component_locate,
> - set_component_locate),
> - __ATTR(type, S_IRUGO, get_component_type, NULL),
> - __ATTR_NULL
> +static DEVICE_ATTR(fault, S_IRUGO | S_IWUSR, get_component_fault,
> + set_component_fault);
> +static DEVICE_ATTR(status, S_IRUGO | S_IWUSR, get_component_status,
> + set_component_status);
> +static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, get_component_active,
> + set_component_active);
> +static DEVICE_ATTR(locate, S_IRUGO | S_IWUSR, get_component_locate,
> + set_component_locate);
> +static DEVICE_ATTR(type, S_IRUGO, get_component_type, NULL);
> +
> +static struct attribute *enclosure_component_attrs[] = {
> + &dev_attr_fault.attr,
> + &dev_attr_status.attr,
> + &dev_attr_active.attr,
> + &dev_attr_locate.attr,
> + &dev_attr_type.attr,
> + NULL
> };
>
> -static struct class enclosure_component_class = {
> - .name = "enclosure_component",
> - .owner = THIS_MODULE,
> - .dev_attrs = enclosure_component_attrs,
> - .dev_release = enclosure_component_release,
> +static struct attribute_group enclosure_group = {
> + .attrs = enclosure_component_attrs,
> +};
> +
> +static struct attribute_group *enclosure_groups[] = {
> + &enclosure_group,
> + NULL
> };
>
> static int __init enclosure_init(void)
> @@ -469,20 +519,12 @@ static int __init enclosure_init(void)
> err = class_register(&enclosure_class);
> if (err)
> return err;
> - err = class_register(&enclosure_component_class);
> - if (err)
> - goto err_out;
>
> return 0;
> - err_out:
> - class_unregister(&enclosure_class);
> -
> - return err;
> }
>
> static void __exit enclosure_exit(void)
> {
> - class_unregister(&enclosure_component_class);
> class_unregister(&enclosure_class);
> }
>
>
>

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