netdev - Re: [PATCH bpf] xdp: Prevent overflow in devmap_hash cost calculation for 32-bit builds

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Date:   Fri, 18 Oct 2019 16:25:24 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Toke Høiland-Jørgensen <toke@...hat.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...com>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Jakub Kicinski <kubakici@...pl>, Yonghong Song <yhs@...com>
Subject: Re: [PATCH bpf] xdp: Prevent overflow in devmap_hash cost calculation
 for 32-bit builds

On Fri, Oct 18, 2019 at 8:36 AM Toke Høiland-Jørgensen <toke@...hat.com> wrote:
>
> Tetsuo pointed out that without an explicit cast, the cost calculation for
> devmap_hash type maps could overflow on 32-bit builds. This adds the
> missing cast.
>
> Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index")
> Reported-by: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
> Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>

gmail delivery lags by a day :(
I applied this patch along with Yonghong's ack to bpf tree
(though I don't have it in my mail box, but it's there in patchworks).

I'm not sure that cleanup Jakub is proposing is possible or better.
Not everything is array_size here and in other places
where cost is computed. u64 is imo much cleaner.