[RFC][PATCH 7/8]: Auto-create ptmx node when mounting devpts

[sukadev at us.ibm.com]

H. Peter Anvin [hpa at zytor.com] wrote:
> Alan Cox wrote:
>>> auto-created, than supporting mknod(2) inside the devpts filesystem. It's 
>>> not a matter of "changing the user space"; it's a matter of what makes 
>>> most sense inside the kernel.
>> Having an extra node with different permissions suddenely appear without
>> warning isn't I think good behaviour.
>
> Hm.  Given that the single-instance mode is the backwards compatibility 
> mode (and it's accessible from outside the filesystem), it probably makes 
> sense to suppress creating this device node when *not* applying the "newns" 
> option, or whatever we want to call it.

I had the new ptmx node only in 'multi-mount' mode initially. But if users
want the multi-mount semantics, /dev/ptmx must be a symlink. If its a symlink,
we break in the single-mount case (which does not have the ptmx node and
we don't support mknod in pts).

>
>> I'm open to being convinced and the
>> other problems with that code are more pressing.

Yes, I will look at the latest in linux-next and the ->driver_data
approach.

But just to confirm, we do want try and keep single-mount semantics.

>
> Agreed.
>
> 	-hpa