Re: [PATCH 2/8] sockopt: Rename SO_TIMESTAMP* to SO_TIMESTAMP*_OLD

[Willem de Bruijn]

On Fri, Nov 30, 2018 at 5:38 PM Deepa Dinamani <deepa.kernel@xxxxxxxxx> wrote:
>
> On Sat, Nov 24, 2018 at 7:59 PM Willem de Bruijn
> <willemdebruijn.kernel@xxxxxxxxx> wrote:
> >
> > On Sat, Nov 24, 2018 at 3:58 AM Deepa Dinamani <deepa.kernel@xxxxxxxxx> wrote:
> > >
> > > SO_TIMESTAMP, SO_TIMESTAMPNS and SO_TIMESTAMPING options, the
> > > way they are currently defined, are not y2038 safe.
> > > Subsequent patches in the series add new y2038 safe versions
> > > of these options which provide 64 bit timestamps on all
> > > architectures uniformly.
> > > Hence, rename existing options with OLD tag suffixes.
> >
> > Why do the existing interfaces have to be renamed when new interfaces are added?
>
> Existing options need to be renamed because of the macro below:
>
> #define SO_TIMESTAMP (sizeof(time_t) == sizeof(__kernel_long_t) ? \
>             SO_TIMESTAMP_OLD : SO_TIMESTAMP_NEW)
>
> SO_TIMESTAMP is now dependent on size of time_t because of the libc flag.

Yes, I understand the mechanism based on libc's definition of time_t
after Arnd's explanation. Please do capture that in the commit
message, for possible future readers who stumble upon the code with
git blame.