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Date: Thu, 2 Feb 2017 20:51:53 +0000
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Laura Abbott <labbott@...oraproject.org>,
Will Deacon <will.deacon@....com>,
Stephen Boyd <sboyd@...eaurora.org>,
Gregory Clement <gregory.clement@...e-electrons.com>,
james.greenhalgh@....com, Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Markus Trippelsdorf <markus@...ppelsdorf.de>,
Andrew Morton <akpm@...ux-foundation.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Joe Perches <joe@...ches.com>
Subject: Re: [PATCH] log2: make order_base_2() behave correctly on const input value zero
> On 2 Feb 2017, at 20:49, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
>
> On Thu, Feb 2, 2017 at 9:04 AM, Ard Biesheuvel
> <ard.biesheuvel@...aro.org> wrote:
>>
>> So update order_base_2() to adhere to its own documented interface.
>
> Ok, looks like you screwed up the types according to the build server.
>
> Making the return type "unsigned long" is slightly excessive. If you
> need an unsigned long to describe the log2 of a number in the kernel,
> you're playing with numbers that are *way* too big.
>
> The old code used "ilog2()", which returns an int.
>
Yeah I cloned roundup_pow_of_2, and failed to spot that ilog2 returns an int. I sent out the v2 already
> Which is plenty big enough of a type.
>
> Linus
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