netdev - Re: [PATCH net-next] Fixes: 0e884c7 ipv4: L3 hash-based multipath: tag

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Date:	Mon, 5 Oct 2015 15:23:10 -0700
From:	Alexander Duyck <alexander.duyck@...il.com>
To:	Peter Nørlund <pch@...bogen.com>,
	netdev@...r.kernel.org
Cc:	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>
Subject: Re: [PATCH net-next] Fixes: 0e884c7 ipv4: L3 hash-based multipath:
 tag

On 10/05/2015 03:14 PM, Peter Nørlund wrote:
> commit 0e884c78ee19e902f300ed147083c28a0c6302f0 ("ipv4: L3 hash-based
> multipath") broke compilation for i386 and arm due to dependency on
> 64-bit division.
>
> The problem is simply solved by using the proper macro for 64-bit
> divison.
>
> Signed-off-by: Peter Nørlund <pch@...bogen.com>
> ---
>   net/ipv4/fib_semantics.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index 0c49d2f..52254e8 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -569,8 +569,8 @@ static void fib_rebalance(struct fib_info *fi)
>   			upper_bound = -1;
>   		} else {
>   			w += nexthop_nh->nh_weight;
> -			upper_bound = DIV_ROUND_CLOSEST(2147483648LL * w,
> -							total) - 1;
> +			upper_bound = DIV_ROUND_CLOSEST_ULL(2147483648ULL * w,
> +							    total) - 1;
>   		}
>   
>   		atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);

Normally the correct comment would include something like the following 
just before the signed-off-by line.
     Fixes: 0e884c78ee19 ("ipv4: L3 hash-based multipath")

I'm also kind of curious.  Why use 2147483648LL instead of just casting 
w as a u64 and shifting by 31?  It seems like that would be more readable.

Thanks.

- Alex
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