Re: Multiple instances of devpts

[H. Peter Anvin]

Eric W. Biederman wrote:
> > /dev/ptmx can be a symlink ptmx -> pts/ptmx, and we add a ptmx instance 
> > inside the devpts filesystem.  Each devpts filesystem is responsible for 
> > its own pool of ptys, with own numbering, etc.
> >
> > This does mean that entries in /dev/pts are more than just plain device 
> > nodes, which they are now (you can cp -a a device node from /dev/pts 
> > into another filesystem and it will still "just work"), but I doubt this 
> > actually matters to anyone.  If anyone cares, now I guess would be a 
> > good time to speak up.
>
> Agreed.   That is another legitimate path.  And if all you care about is
> isolation and not dealing with the general class of problems with the
> global device number to device mapping that is sane.  I know we have
> several other virtual devices that we tend to care about but ptys are
> the real world pain point.

Thinking about it further, allowing this restriction would also allow a 
whole lot of cleanups inside the pty setup, since it would eliminate the 
need to do a separate lookup to find the corresponding devpts entry in 
pty_open().  The benefit here comes from the closer coupling between the 
pty and the devpts filesystem and isn't at all related to namespaces, 
but it's a very nice side benefit.

	-hpa
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/