Re: [PATCH] tty: Remove dead termiox code

[Jiri Slaby <jirislaby@kernel.org>]

On 08. 12. 20, 12:13, Christoph Hellwig wrote:
> On Fri, Dec 04, 2020 at 09:20:39AM +0100, Jiri Slaby wrote:
>>>>> Delete this dead code; but leave the definition of struct termiox in the
>>>>> UAPI headers intact.
>>>>
>>>> I am thinking -- can/should we mark the structure as deprecated so that
>>>> userspace stops using it eventually?
>>>
>>> If it doesn't do anything, how can userspace even use it today?  :)
>>
>> Well, right. I am in favor to remove it, BUT: what if someone tries that
>> ioctl and bails out if EINVAL is returned. I mean: if they define a local
>> var of that struct type and pass it to the ioctl, we would break the build
>> by removing the struct completely. Even if the code didn't do anything
>> useful, it still could be built. So is this very potential breakage OK?
> 
> Um, we do guarantee a stable ABI.  We have never guaranteed that all old
> crappy code will continue to compile, although we avoid gratious
> breakage.  And assuming there ever was code using termiox (which I'm not
> sure about to start with) it will surely have some form of feature
> check, and I think we are better off with that feature check not
> detecting the presence as that would be completely pointless.
> 
> Or in short: by keeping the uapi definition we do userspace software a
> disfavor.

OK, even better. I will remove it once I get to it (if noone beats me to 
it, of course).

thanks,
-- 
js
suse labs