linux-kernel - Re: [PATCH 4/5] uio: Support 2^MINOR

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Date:	Fri, 17 Sep 2010 22:36:50 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
cc:	Greg Kroah-Hartman <gregkh@...e.de>,
	"Hans J. Koch" <hjk@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] uio: Support 2^MINOR_BITS minors

On Tue, 14 Sep 2010, Eric W. Biederman wrote:

> 
> register_chrdev limits uio devices to 256 minor numbers which causes
> problems on one system I have with 384+ uio devices.  So instead set
> UIO_MAX_DEVICES to the maximum number of minors and use
> alloc_chrdev_region to reserve the uio minors.
> 
> The final result is that the code works the same but the uio driver now
> supports any minor the idr allocator comes up with.
> 
> Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>

One minor nit:

> +	result = alloc_chrdev_region(&uio_dev, 0, UIO_MAX_DEVICES, name);
> +	if (result)
> +		goto out;

  		return result;

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>

> +
> +	result = -ENOMEM;
> +	cdev = cdev_alloc();
> +	if (!cdev)
> +		goto out_unregister;
> +
> +	cdev->owner = THIS_MODULE;
> +	cdev->ops = &uio_fops;
> +	kobject_set_name(&cdev->kobj, "%s", name);
> +
> +	result = cdev_add(cdev, uio_dev, UIO_MAX_DEVICES);
> +	if (result)
> +		goto out_put;
> +
> +	uio_major = MAJOR(uio_dev);
> +	uio_cdev = cdev;
> +	result = 0;
> +out:
> +	return result;
> +out_put:
> +	kobject_put(&cdev->kobj);
> +out_unregister:
> +	unregister_chrdev_region(uio_dev, UIO_MAX_DEVICES);
> +	goto out;
>  }
>  
>  static void uio_major_cleanup(void)
>  {
> -	unregister_chrdev(uio_major, "uio");
> +	unregister_chrdev_region(MKDEV(uio_major, 0), UIO_MAX_DEVICES);
> +	cdev_del(uio_cdev);
>  }
>  
>  static int init_uio_class(void)
> -- 
> 1.7.2.2
> 
> --
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