netdev - Re: [PATCH v2 net] net: solve a NAPI race

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Message-ID: <1488389559.9415.300.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Wed, 01 Mar 2017 09:32:39 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     David Laight <David.Laight@...lab.com>,
        David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: Re: [PATCH v2 net] net: solve a NAPI race

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.