Re: Adding PCMCIA support to the kernel tree -- developers needed.

[Oliver Neukum <Oliver.Neukum@lrz.uni-muenchen.de>]

> > You can retry, you are right. I failed to see that.
> > But you seem to suffer from the name reuse race.
> >
> > reality			task A			task B
> > plug in dev A
> > 			bind dev A to name 0
> > unplug dev A
> > 						unbind name 0
> > plug in dev B
> > 						bind dev B to name 0
> > 			do something arbitrary
> > 			to the dev associated
> > 			with name 0
> >
> > If the kernel would select name 0, it could lock on name 0.
> > With your scheme this is hard to do.
>
> Unbind on name 0 should block until task A finishes the arbitrary stuff.
> Is there any problem with that? We could even have a 'setup finished'
> ioctl for this, though I think I'd prefer just having one task per action.

This would work provided that the lock is taken atomically with binding to 
the name.

> > Nor do you absolutely need to.
> > You can already rename network devices by ioctl.
> > For everything else a humble symlink should do the job, shouldn't it ?
>
> Yes, but with humble symlinks you will run out of minor/major numbers soon.

Why is that ? Even if you assign numbers by the agent you would take them out 
of a pool of numbers the kernel could also use.
In both cases it would seem that devices use the same amount of numbers.

> > Else you introduce complexity without much gain.
> > And you need renaming in any case, as device names may have been assigned
> > during boot.
>
> Yes. Symlinks would help here, however, you'd probably need devfs in
> that case.

I can see devfs helping tremendously with providing stable names, but why is 
it necessary ?

	Regards
		Oliver

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