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

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Date:	Fri, 17 Sep 2010 22:57:05 +0200
From:	"Hans J. Koch" <hjk@...utronix.de>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	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 Fri, Sep 17, 2010 at 10:36:50PM +0200, Thomas Gleixner wrote:
> 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;

Well, ok... Greg, can you fix this when you take the patch into your tree?

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

Signed-off-by: Hans J. Koch <hjk@...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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