Re: [PATCH] TTY: export NR_LDISC and N_* line discipline numbers to user-space

[Florian Fainelli <ffainelli@freebox.fr>]

On Tuesday 24 May 2011 15:33:53 Greg KH wrote:
> On Tue, May 24, 2011 at 03:17:23PM +0200, Florian Fainelli wrote:
> > Hello,
> > 
> > On Tuesday 24 May 2011 14:40:44 Greg KH wrote:
> > > On Tue, May 24, 2011 at 10:43:03AM +0200, Florian Fainelli wrote:
> > > > From: Florian Fainelli <ffainelli@freebox.fr>
> > > > 
> > > > Since commit (4564f9e5: consolidate line discipline number
> > > > definitions) the patch moved all line discipline number from a
> > > > per-architecture termios.h to a shared one: tty.h. However, prior to
> > > > this consolidation work, the line discipline numbers were outside of
> > > > an ifdef
> > > > __KERNEL__/endif block so these numbers used to be exported to
> > > > user-space.
> > > > 
> > > > Since such numbers are kernel ABI anyway, and tty.h is already
> > > > included for user- space header processing, just move these relevant
> > > > defines outside of the ifdef __KERNEL__/endif block in
> > > > include/linux/tty.h.
> > > 
> > > Any reason you didn't copy _any_ of the people who signed off on that
> > > patch, or the original author of that patch?
> > 
> > No particular reason but my mistake, fixed that.
> > 
> > > Anyway, this is been this way for four years, since the 2.6.21 kernel
> > > release.  Since no one has noticed, or complained, since then, how much
> > > a problem is this really?
> > 
> > This is a problem because you may have out of tree drivers using a line
> > discpline number, and you do not want your companion user-space
> > application to have to use a different line discpline number but the one
> > the kernel should provide.
> > 
> > > Meaning, why has it taken this long for anyone to notice?
> > 
> > - long standing user-space applications such as pppd got their N_PPP long
> > ago, and do not have to worry about N_PPP being renumbered so they can
> > just define it in pppd's sources it won't break
> > 
> > - I started implementing a line discipline driver only a couple of months
> > ago and then realized that such ABI should have been exported
> 
> Ok, then it really isn't that important of a change :)
> 
> I'll queue it up for the next major merge window after this one, thanks.

Thanks!
--
Florian