Re: Question: how to retrieve drvdata from open() ?

[Christophe LEROY <christophe.leroy@c-s.fr>]

Hi, thanks for your answwer,

Le 27/11/2017 à 17:38, Matthew Wilcox a écrit :
> On Mon, Nov 27, 2017 at 04:18:42PM +0100, Christophe LEROY wrote:
>> When registering a device node with device_create(), it is possible to pass
>> a drvdata pointer.
>>
>> How can I retrieve that drvdata pointer from the open() fops ? I've not been
>> able to find any exemple.
> 
> You're not supposed to do it that way ... assuming you're talking about
> a character device, you embed the cdev in your own data structure and
> do this:
> 
> struct my_struct *my = container_of(inode->i_cdev, struct my_struct, cdev);
> 
> after calling:
> 
> cdev_init(&my->cdev, &my_dev_fops);
> 
> You'll use the drvdata when trying to go from the struct device to
> 'my_struct'.  There's no struct device in struct cdev.  I mean, you
> could probably get to it, but it's easier if you just do it the way that
> everybody else does it.
> 

I see, you are right I'm talking about a character device.

The driver I'm trying to clean is using __register_chrdev() which hides 
cdev and cdev operations. Does it mean it has to be changed to do cdev 
operations explicitely ?