Re: [PATCH] proc: move the adding option Ngid to the end of proc/PID/status

Alexey Dobriyan
2015-04-23T20:32:30Z

On Tue, Apr 21, 2015 at 11:11:19AM -0400, Tejun Heo wrote:
> On Tue, Apr 21, 2015 at 05:00:07PM +0300, Alexey Dobriyan wrote:
> > > The only reason for changing the position is because
> > > there's this specific breakage. The goal should be working around
> > > that specific case while keeping the impact minimum on everyone else.
> >
> > If there are TWO incorrect parsers, one for TracerPid, another for Ngid,
> > you CAN'T workaround it. And if you can't workaround you choose code
> > which was written first, namely, TracerPid one.
>
> Not when the code has been out for 1.5 years. Minimizing the
> disturbance is the better course of action. Look at the file. If you
> move ngid to the end now, it's gonna shift most of the file content,
> which is what caused the problem in the first place.
>
> We don't know what's out there which again was the same problem which
> triggered this thread in the first place. Why would you take the same
> amount of risk when you can fix the known issue with less amount of
> changes?

There are 2 fields before Ngid and 35+ after Ngid. So the risk is not
the same. Potentionally, Ngid addition broke almost every parser.

> Just put ngid after tracerpid. That way, we can fix the
> known problems while changing the offsets of only four fields. At
> this point, no change to the file layout is "right". Such thing isn't
> defined regardless of who came first. The only thing we can do is
> working around the known cases while minimizing possible impacts.

We'll return to this thread when next breakage will be reported,
I promise. :^)