getting device info from device node

getting device info from device node

[Oliver Neukum]

Hi Greg,

I must disagree. The most basic thing about configuring
a device is identifying it. You must be able to tell what it is.

However I think I found a relatively clean way.
You can return a name from an ioctl().
You just can't return the one human readable name.
You can return a name which is unique and can only
be used while the device is still plugged in.

	Regards
		Oliver

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Re: getting device info from device node

[Greg KH]

On Wed, Jun 05, 2002 at 12:13:18AM +0200, Oliver Neukum wrote:
> Hi Greg,
> 
> I must disagree. The most basic thing about configuring
> a device is identifying it. You must be able to tell what it is.
> 
> However I think I found a relatively clean way.
> You can return a name from an ioctl().
> You just can't return the one human readable name.
> You can return a name which is unique and can only
> be used while the device is still plugged in.

Great, how does the kernel create this "name"?

thanks,

greg k-h

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Re: getting device info from device node

[Oliver Neukum]

Am Mittwoch, 5. Juni 2002 00:19 schrieben Sie:
> On Wed, Jun 05, 2002 at 12:13:18AM +0200, Oliver Neukum wrote:
> > Hi Greg,
> >
> > I must disagree. The most basic thing about configuring
> > a device is identifying it. You must be able to tell what it is.
> >
> > However I think I found a relatively clean way.
> > You can return a name from an ioctl().
> > You just can't return the one human readable name.
> > You can return a name which is unique and can only
> > be used while the device is still plugged in.
>
> Great, how does the kernel create this "name"?

I'd suggest a fixed prefix+pid+counter.
What it actually is doesn't matter if it's unique.
It's simply a directory with the files in it hard links
to the files in the persistent directory.
The trick is that we refuse to open files in it, if the
name has been invalidated by device removal.
I am not sure how much of the vfs locking we could use.
I am not Al Viro, that's why it didn't occur to me earlier.

	Regards
		Oliver

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