From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v2 net] net: solve a NAPI race
Date: Wed, 01 Mar 2017 09:32:39 -0800
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Cc: David Laight <David.Laight@aculab.com>,
        David Miller <davem@davemloft.net>,
        netdev <netdev@vger.kernel.org>,
        Tariq Toukan <tariqt@mellanox.com>,
        Saeed Mahameed <saeedm@mellanox.com>
To: Alexander Duyck <alexander.duyck@gmail.com>
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On Wed, 2017-03-01 at 08:14 -0800, Alexander Duyck wrote:

> What build flags are you using?  With -Os or -O2 I have seen it
> convert the /b * c into a single shift.
> 


Because b & c are unsigned in our case.

I presume David tried signed integers, this is why gcc does that.