netdev - Re: [net-next,1/3] netem: convert to qdisc_watchdog_schedule

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Message-ID: <20171114144917.66f0047c@xeon-e3>
Date:   Tue, 14 Nov 2017 14:49:17 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     James Hogan <james.hogan@...s.com>
Cc:     Dave Taht <dave.taht@...il.com>, <netdev@...r.kernel.org>,
        <linux-next@...r.kernel.org>, <linux-mips@...ux-mips.org>,
        Ralf Baechle <ralf@...ux-mips.org>
Subject: Re: [net-next,1/3] netem: convert to qdisc_watchdog_schedule_ns

On Tue, 14 Nov 2017 21:11:13 +0000
James Hogan <james.hogan@...s.com> wrote:

> On Tue, Nov 07, 2017 at 12:59:34PM -0800, Dave Taht wrote:
> > diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
> > index db0228a..443a75d 100644
> > --- a/net/sched/sch_netem.c
> > +++ b/net/sched/sch_netem.c  
> 
> ...
> 
> > @@ -305,11 +305,11 @@ static bool loss_event(struct netem_sched_data *q)
> >   * std deviation sigma.  Uses table lookup to approximate the desired
> >   * distribution, and a uniformly-distributed pseudo-random source.
> >   */
> > -static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
> > -				struct crndstate *state,
> > -				const struct disttable *dist)
> > +static s64 tabledist(s64 mu, s64 sigma,  
> 
> sigma is used in a modulo operation in this function, which results in
> this error on a bunch of MIPS configs once it is made 64-bits wide:
> 
> net/sched/sch_netem.o In function `tabledist':
> net/sched/sch_netem.c:330: undefined reference to `__moddi3'
> 
> Should that code not be using <linux/math64.h>, i.e. div_s64_rem() now
> that it is 64bit?
> 
> Thanks
> James

Not really since random is only 32 bit, the sigma value being 64 bit makes
no sense really.

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