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Date:   Tue, 13 Aug 2019 21:14:06 +0200
From:   Florian Westphal <fw@strlen.de>
To:     Ander Juaristi <a@juaristi.eus>
Cc:     netfilter-devel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] netfilter: nft_meta: support for time matching
Message-ID: <20190813191406.lhsz3y4bbmuzixxi@breakpoint.cc>
References: <20190813183820.6659-1-a@juaristi.eus>
 <20190813183820.6659-2-a@juaristi.eus>
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Ander Juaristi <a@juaristi.eus> wrote:
> +++ b/net/netfilter/nft_meta.c
> @@ -28,6 +28,27 @@
>  
>  static DEFINE_PER_CPU(struct rnd_state, nft_prandom_state);
>  
> +static u8 nft_meta_weekday(unsigned long secs)
> +{
> +	u8 wday;
> +	unsigned int dse;
> +
> +	secs -= 60 * sys_tz.tz_minuteswest;
> +	dse = secs / 86400;

This will probably fail to compile (link) on 32bit arches.
You need to use do_div() here.

> +	wday = (4 + dse) % 7;

This is fine, as this only involves 32bit integers.