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Date: Fri, 16 Dec 2022 11:10:41 +0100 From: Pablo Neira Ayuso <pablo@...filter.org> To: Julian Anastasov <ja@....bg> Cc: Arnd Bergmann <arnd@...nel.org>, Simon Horman <horms@...ge.net.au>, Arnd Bergmann <arnd@...db.de>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Jiri Wiesner <jwiesner@...e.de>, netdev@...r.kernel.org, lvs-devel@...r.kernel.org, netfilter-devel@...r.kernel.org, coreteam@...filter.org, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] ipvs: use div_s64 for signed division 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@...db.de> > > > > 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@...db.de> > > --- > > 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@....bg> >
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