On Tue, Mar 04, 2014 at 08:36:28AM +0100, Mike Galbraith wrote:
> (boing boing boing... hell with it, today doesn't exist;)
you lost me at boing.. :)
> On Tue, 2014-03-04 at 08:31 +0100, Mike Galbraith wrote:
> > On Tue, 2014-03-04 at 08:20 +0100, Henrik Austad wrote:
> > > On Tue, Mar 04, 2014 at 06:20:09AM +0100, Mike Galbraith wrote:
> > > > Greetings,
> > > >
> > > > While rummaging around looking for HTH a gaggle of weird a$$ machines
> > > > can manage to timewarp back and forth by exactly 208 days, I stumbled
> > > > across $subject which looks like it may want to borrow Salman's fix.
> > > >
> > > > clocksource: avoid unnecessary overflow in cyclecounter_cyc2ns()
> > > >
> > > > As per 4cecf6d401a "sched, x86: Avoid unnecessary overflow in
> > > > sched_clock",
> > > > cycles * mult >> shift is overflow prone. so give it the same treatment.
> > > >
> > > > Cc: Salman Qazi <sq...@google.com>
> > > > Cc: John Stultz <johns...@us.ibm.com>
> > > > Signed-off-by: Mike Galbraith <bitbuc...@online.de>
> > > > ---
> > > > include/linux/clocksource.h | 11 ++++++++---
> > > > 1 file changed, 8 insertions(+), 3 deletions(-)
> > > >
> > > > --- a/include/linux/clocksource.h
> > > > +++ b/include/linux/clocksource.h
> > > > @@ -77,13 +77,18 @@ struct timecounter {
> > > > *
> > > > * XXX - This could use some mult_lxl_ll() asm optimization. Same code
> > > > * as in cyc2ns, but with unsigned result.
> > > > + *
> > > > + * Because it is the same as x86 __cycles_2_ns, give it the same
> > > > treatment as
> > > > + * commit 4cecf6d401a "sched, x86: Avoid unnecessary overflow in
> > > > sched_clock"
> > > > + * to avoid a potential cycles * mult overflow.
> > >
> > > Do we normally reference a particular commit in a comment? Why not just
> > > grab the same comment and add a "this is grabbed from arch/x86/... ?
> >
> > Fewer '+' signs? History doesn't go away, so seems fine to me.
I wasn't thinking about the number of +'s in the code, but rather
referencing other parts of the code from the code and particular commits in
the commit-msg itself. It was the code<->commitmsg interface I was
pondering.
Besides, it wasn't meant as "you shouldn't do that", but more "is it ok to
do that?" :)
--
Henrik Austad
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