netdev - Re: [PATCH net-next] net: tcp: dctcp_update

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Message-ID: <5579F894.3030104@iogearbox.net>
Date:	Thu, 11 Jun 2015 23:07:32 +0200
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	David Miller <davem@...emloft.net>
CC:	netdev <netdev@...r.kernel.org>, Florian Westphal <fw@...len.de>
Subject: Re: [PATCH net-next] net: tcp: dctcp_update_alpha() fixes.

On 06/11/2015 07:11 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> dctcp_alpha can be read by from dctcp_get_info() without
> synchro, so use WRITE_ONCE() to prevent compiler from using
> dctcp_alpha as a temporary variable.
>
> Also, playing with small dctcp_shift_g (like 1), can expose
> an overflow with 32bit values shifted 9 times before divide.
>
> Use an u64 field to avoid this problem, and perform the divide
> only if acked_bytes_ecn is not zero.
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Change looks correct to me, thanks Eric!

Acked-by: Daniel Borkmann <daniel@...earbox.net>
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