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Date: Tue, 27 Sep 2016 18:23:50 +0800 From: Liping Zhang <zlpnobody@...il.com> To: Vishwanath Pai <vpai@...mai.com> Cc: Pablo Neira Ayuso <pablo@...filter.org>, Patrick McHardy <kaber@...sh.net>, Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>, johunt@...mai.com, Netfilter Developer Mailing List <netfilter-devel@...r.kernel.org>, coreteam@...filter.org, Linux Kernel Network Developers <netdev@...r.kernel.org>, Vishwanath Pai <pai.vishwain@...il.com> Subject: Re: [PATCH] Fix link error in 32bit arch because of 64bit division Hi Vishwanath Pai, 2016-09-27 15:42 GMT+08:00 Vishwanath Pai <vpai@...mai.com>: > Fix link error in 32bit arch because of 64bit division This should be "netfilter: xt_hashlimit: fix ... " > > --- a/net/netfilter/xt_hashlimit.c > +++ b/net/netfilter/xt_hashlimit.c > @@ -465,19 +465,20 @@ static u64 user2credits(u64 user, int revision) > { > if (revision == 1) { > /* If multiplying would overflow... */ > - if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY_v1)) > + if (user > div64_u64(0xFFFFFFFF, (HZ*CREDITS_PER_JIFFY_v1))) Here divisor and dividend are all 32-bit integer, so covert "/" to div64_u64 seems unnecessary. > /* Divide first. */ > - return (user / XT_HASHLIMIT_SCALE) *\ > + return div64_u64(user, XT_HASHLIMIT_SCALE) *\ > HZ * CREDITS_PER_JIFFY_v1; > > - return (user * HZ * CREDITS_PER_JIFFY_v1) \ > - / XT_HASHLIMIT_SCALE; > + return div64_u64((user * HZ * CREDITS_PER_JIFFY_v1), > + XT_HASHLIMIT_SCALE); > } else { > - if (user > 0xFFFFFFFFFFFFFFFF / (HZ*CREDITS_PER_JIFFY)) > - return (user / XT_HASHLIMIT_SCALE_v2) *\ > + if (user > div64_u64(0xFFFFFFFFFFFFFFFF, (HZ*CREDITS_PER_JIFFY))) 0xFFFFFFFFFFFFFFFF and "HZ*CREDITS_PER_JIFFY" are both constant, and GCC will do constant folding optimization, so I think convert "/" to div64_u64 here is also unnecessary. > + return div64_u64(user, XT_HASHLIMIT_SCALE_v2) *\ > HZ * CREDITS_PER_JIFFY; > > - return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE_v2; > + return div64_u64((user * HZ * CREDITS_PER_JIFFY), > + XT_HASHLIMIT_SCALE_v2); > } > } >
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