Re: [PATCH net-next 1/4] time64.h: define PSEC_PER_NSEC and use it in tc-taprio

[Vladimir Oltean]

Hi Vincenzo,

On Mon, Jun 27, 2022 at 08:52:51AM +0100, Vincenzo Frascino wrote:
> Hi Vladimir,
> 
> On 6/26/22 13:05, Vladimir Oltean wrote:
> > Time-sensitive networking code needs to work with PTP times expressed in
> > nanoseconds, and with packet transmission times expressed in
> > picoseconds, since those would be fractional at higher than gigabit
> > speed when expressed in nanoseconds.
> > 
> > Convert the existing uses in tc-taprio to a PSEC_PER_NSEC macro.
> > 
> > Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> > Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
> > ---
> >  include/vdso/time64.h  | 1 +
> >  net/sched/sch_taprio.c | 4 ++--
> >  2 files changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/vdso/time64.h b/include/vdso/time64.h
> > index b40cfa2aa33c..f1c2d02474ae 100644
> > --- a/include/vdso/time64.h
> > +++ b/include/vdso/time64.h
> > @@ -6,6 +6,7 @@
> >  #define MSEC_PER_SEC	1000L
> >  #define USEC_PER_MSEC	1000L
> >  #define NSEC_PER_USEC	1000L
> > +#define PSEC_PER_NSEC	1000L
> 
> Are you planning to use this definition in the vdso library code? If not, you
> should define PSEC_PER_NSEC in "include/linux/time64.h". The vdso namespace
> should contain only the definitions shared by the implementations of the kernel
> and of the vdso library.

I am not. I thought it would be ok to preserve the locality of
definitions by placing this near the others of its kind, since a macro
doesn't affect the compiled vDSO code in any way. But if you prefer, I
can create a new mini-section in linux/time64.h. Any preference on where
exactly to place that definition within the file?