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Date: Sun, 25 Jan 2015 20:33:16 +0800
From: Greg KH <gregkh@...uxfoundation.org>
To: Mandeep Sandhu <mandeep.sandhu@...ninc.com>
Cc: hjk@...sjkoch.de, linux-kernel@...r.kernel.org,
viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/4] uio: Simplify the lifetime logic of struct
uio_device.
On Fri, Jan 16, 2015 at 10:49:36AM -0800, Mandeep Sandhu wrote:
> Embed struct device into struct uio_device, and use
> the refcounting and the release method of struct device
> to control struct uio_device.
>
> This allows device_create and device_destroy to be replaced
> with the more standard device_register and device_unregister,
> and allows the struct device reference count to act as a
> reference count on struct idev as well.
>
> Tested-by: Mandeep Sandhu <mandeep.sandhu@...ninc.com>
> Signed-off-by: Mandeep Sandhu <mandeep.sandhu@...ninc.com>
> ---
> drivers/uio/uio.c | 41 ++++++++++++++++++++++++++---------------
> include/linux/uio_driver.h | 3 ++-
> 2 files changed, 28 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 6276f13..350b81b 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -16,7 +16,6 @@
> #include <linux/module.h>
> #include <linux/init.h>
> #include <linux/poll.h>
> -#include <linux/device.h>
> #include <linux/slab.h>
> #include <linux/mm.h>
> #include <linux/idr.h>
> @@ -270,7 +269,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
> if (!map_found) {
> map_found = 1;
> idev->map_dir = kobject_create_and_add("maps",
> - &idev->dev->kobj);
> + &idev->device.kobj);
> if (!idev->map_dir)
> goto err_map;
> }
> @@ -295,7 +294,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
> if (!portio_found) {
> portio_found = 1;
> idev->portio_dir = kobject_create_and_add("portio",
> - &idev->dev->kobj);
> + &idev->device.kobj);
> if (!idev->portio_dir)
> goto err_portio;
> }
> @@ -334,7 +333,7 @@ err_map_kobj:
> kobject_put(&map->kobj);
> }
> kobject_put(idev->map_dir);
> - dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
> + dev_err(&idev->device, "error creating sysfs files (%d)\n", ret);
> return ret;
> }
>
> @@ -371,7 +370,7 @@ static int uio_get_minor(struct uio_device *idev)
> idev->minor = retval;
> retval = 0;
> } else if (retval == -ENOSPC) {
> - dev_err(idev->dev, "too many uio devices\n");
> + dev_err(&idev->device, "too many uio devices\n");
> retval = -EINVAL;
> }
> mutex_unlock(&minor_lock);
> @@ -785,6 +784,13 @@ static void release_uio_class(void)
> uio_major_cleanup();
> }
>
> +static void uio_device_release(struct device *dev)
> +{
> + struct uio_device *idev = dev_get_drvdata(dev);
No, calculate the offset of, then you don't need to mess with drvdata,
as that shouldn't be used by the "core" of a subsystem.
> +
> + devm_kfree(dev->parent, idev);
> +}
> +
> /**
> * uio_register_device - register a new userspace IO device
> * @owner: module that creates the new device
> @@ -819,14 +825,19 @@ int __uio_register_device(struct module *owner,
> if (ret)
> return ret;
>
> - idev->dev = device_create(&uio_class, parent,
> - MKDEV(uio_major, idev->minor), idev,
> - "uio%d", idev->minor);
> - if (IS_ERR(idev->dev)) {
> - printk(KERN_ERR "UIO: device register failed\n");
> - ret = PTR_ERR(idev->dev);
> + idev->device.devt = MKDEV(uio_major, idev->minor);
> + idev->device.class = &uio_class;
> + idev->device.parent = parent;
> + idev->device.release = uio_device_release;
> + dev_set_drvdata(&idev->device, idev);
This will not be needed if you fix up the release function.
> +
> + ret = kobject_set_name(&idev->device.kobj, "uio%d", idev->minor);
dev_set_name()?
> + if (ret)
> + goto err_device_create;
> +
> + ret = device_register(&idev->device);
> + if (ret)
> goto err_device_create;
> - }
>
> ret = uio_dev_add_attributes(idev);
> if (ret)
> @@ -835,7 +846,7 @@ int __uio_register_device(struct module *owner,
> info->uio_dev = idev;
>
> if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
> - ret = devm_request_irq(idev->dev, info->irq, uio_interrupt,
> + ret = devm_request_irq(&idev->device, info->irq, uio_interrupt,
> info->irq_flags, info->name, idev);
> if (ret)
> goto err_request_irq;
> @@ -846,7 +857,7 @@ int __uio_register_device(struct module *owner,
> err_request_irq:
> uio_dev_del_attributes(idev);
> err_uio_dev_add_attributes:
> - device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
> + device_unregister(&idev->device);
> err_device_create:
> uio_free_minor(idev);
> return ret;
> @@ -871,7 +882,7 @@ void uio_unregister_device(struct uio_info *info)
>
> uio_dev_del_attributes(idev);
>
> - device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
> + device_unregister(&idev->device);
>
> return;
> }
> diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
> index 32c0e83..e8f7f82 100644
> --- a/include/linux/uio_driver.h
> +++ b/include/linux/uio_driver.h
> @@ -14,6 +14,7 @@
> #ifndef _UIO_DRIVER_H_
> #define _UIO_DRIVER_H_
>
> +#include <linux/device.h>
> #include <linux/fs.h>
> #include <linux/interrupt.h>
>
> @@ -65,7 +66,7 @@ struct uio_port {
>
> struct uio_device {
> struct module *owner;
> - struct device *dev;
> + struct device device;
No need to rename the variable, just change it from being a pointer.
thanks,
greg k-h
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