linux-kernel - Re: [PATCH] block: Use BIT macro from include/linux/bitops.h

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Message-ID: <555CE3C4.7010406@kernel.dk>
Date:	Wed, 20 May 2015 13:43:00 -0600
From:	Jens Axboe <axboe@...nel.dk>
To:	Jagan Teki <jteki@...nedev.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Wolfram Sang <wsa@...-dreams.de>
Subject: Re: [PATCH] block: Use BIT macro from include/linux/bitops.h

On 05/20/2015 01:41 PM, Jagan Teki wrote:
> On 21 May 2015 at 00:52, Jens Axboe <axboe@...nel.dk> wrote:
>> On 05/18/2015 01:14 PM, Jagan Teki wrote:
>>>
>>> Replace (1 << nr) to BIT(nr) where nr = 0, 1, 2 .... 31
>>
>>
>> I don't like it, I think it hurts readability.
>
> What do you mean by don't like, using kernel defined macro instead of
> numerical assignments huts readability?

In the context of the patch, BIT(0) == (1 << 0) is obvious. But if I 
just came across BIT(7) in the code, I'd have to check, whereas anyone 
would immediately know that (1 << 7) is the 7th bit set. Hence, 
readability is worse, and that's important.

-- 
Jens Axboe

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