Hi Julian,
On Thu, Dec 15, 2022 at 09:01:59PM +0200, Julian Anastasov wrote:
>
> Hello,
>
> On Thu, 15 Dec 2022, Arnd Bergmann wrote:
>
> > From: Arnd Bergmann <arnd@xxxxxxxx>
> >
> > do_div() is only well-behaved for positive numbers, and now warns
> > when the first argument is a an s64:
> >
> > net/netfilter/ipvs/ip_vs_est.c: In function 'ip_vs_est_calc_limits':
> > include/asm-generic/div64.h:222:35: error: comparison of distinct pointer types lacks a cast [-Werror]
> > 222 | (void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
> > | ^~
> > net/netfilter/ipvs/ip_vs_est.c:694:17: note: in expansion of macro 'do_div'
> > 694 | do_div(val, loops);
>
> net-next already contains fix for this warning
> and changes val to u64.
Arnd's patch applies fine on top of net-next, maybe he is addressing
something else?
> > Convert to using the more appropriate div_s64(), which also
> > simplifies the code a bit.
> >
> > Fixes: 705dd3444081 ("ipvs: use kthreads for stats estimation")
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> > ---
> > net/netfilter/ipvs/ip_vs_est.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
> > index ce2a1549b304..dbc32f8cf1f9 100644
> > --- a/net/netfilter/ipvs/ip_vs_est.c
> > +++ b/net/netfilter/ipvs/ip_vs_est.c
> > @@ -691,15 +691,13 @@ static int ip_vs_est_calc_limits(struct netns_ipvs *ipvs, int *chain_max)
> > }
> > if (diff >= NSEC_PER_SEC)
> > continue;
> > - val = diff;
> > - do_div(val, loops);
> > + val = div_s64(diff, loops);
>
> On CONFIG_X86_32 both versions execute single divl
> for our case but div_s64 is not inlined. I'm not expert in
> this area but if you think div_u64 is more appropriate then
> post another patch. Note that now val is u64 and
> min_est is still s32 (can be u32).
>
> > if (!min_est || val < min_est) {
> > min_est = val;
> > /* goal: 95usec per chain */
> > val = 95 * NSEC_PER_USEC;
> > if (val >= min_est) {
> > - do_div(val, min_est);
> > - max = (int)val;
> > + max = div_s64(val, min_est);
> > } else {
> > max = 1;
> > }
> > --
> > 2.35.1
>
> Regards
>
> --
> Julian Anastasov <ja@xxxxxx>
>
