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

[Wang, Xiaoming]

Dear tejun

> -----Original Message-----
> From: Tejun Heo [mailto:htejun@xxxxxxxxx] On Behalf Of Tejun Heo
> Sent: Friday, April 17, 2015 11:13 PM
> To: Alexey Dobriyan
> Cc: Wang, Xiaoming; Linux Kernel; Mel Gorman; Andrew Morton
> Subject: Re: [PATCH] proc: move the adding option Ngid to the end of
> proc/PID/status
> 
> On Fri, Apr 17, 2015 at 06:05:55PM +0300, Alexey Dobriyan wrote:
> > Moving Ngid to the end of file minimizes risk of breakage.
> 
> Hmmm... how so?  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.
> It doesn't matter whether the initial change was good or bad, the kernel w/ the
> new layout is already out in the wild and it has been out there for a while.  How
> is risking changing offsets on most of the fields on those kernels a good idea?
> Mimize the changes to work around the specific case.
> 

Do you mean we should to update the every application
under this new order?
> > Correctly written code doesn't care.
> > Code which hardcodes layout won't notice.
> 
> Huh?  Code which hardcodes layout since 1.5 years ago will definitely notice.
> 

As I mentioned before not all user update the kernel so frequently.
They will met this issue, if update to the 3.13,
The application failed to use which may run well previously.
> > It would be OK argument if gentlemen from Intel send "let's
> > futureproof and move Ngid because someone might depend on exact
> position" patch.
> >
> > Primum non nocere.
> 
> ajlkjaeligjlakd lakjeilgjal flekjfa.
> 
> --
> tejun
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