linux-kernel - RE: [PATCH next 10/11] block: Use a boolean expression instead of max() on booleans

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Date: Mon, 29 Jan 2024 11:47:37 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: David Laight <David.Laight@...LAB.COM>, "'linux-kernel@...r.kernel.org'"
 <linux-kernel@...r.kernel.org>, 'Linus
 Torvalds' <torvalds@...ux-foundation.org>, 'Netdev'
 <netdev@...r.kernel.org>, "'dri-devel@...ts.freedesktop.org'"
 <dri-devel@...ts.freedesktop.org>
Cc: 'Jens Axboe' <axboe@...nel.dk>, "'Matthew Wilcox (Oracle)'"
 <willy@...radead.org>, 'Christoph Hellwig' <hch@...radead.org>,
 "'linux-btrfs@...r.kernel.org'" <linux-btrfs@...r.kernel.org>, 'Andrew
 Morton' <akpm@...ux-foundation.org>, 'Andy Shevchenko'
 <andriy.shevchenko@...ux.intel.com>, "'David S . Miller'"
 <davem@...emloft.net>, 'Dan Carpenter' <dan.carpenter@...aro.org>
Subject: RE: [PATCH next 10/11] block: Use a boolean expression instead of
 max() on booleans

On Mon, 29 Jan 2024, David Laight <David.Laight@...LAB.COM> wrote:
> From: Jani Nikula
>> Sent: 29 January 2024 09:08
>> 
>> On Sun, 28 Jan 2024, David Laight <David.Laight@...LAB.COM> wrote:
>> > blk_stack_limits() contains:
>> > 	t->zoned = max(t->zoned, b->zoned);
>> > These are bool, so it is just a bitwise or.
>> 
>> Should be a logical or, really. And || in code.
>
> Not really, bitwise is fine for bool (especially for 'or')
> and generates better code.

Logical operations for booleans are more readable for humans than
bitwise. And semantically correct.

With a = b || c you know what happens regardless of the types in
question. a = b | c you have to look up the types to know what's going
on.

To me, better code only matters if it's a hotpath.

That said, not my are of maintenance, so *shrug*.

BR,
Jani.

-- 
Jani Nikula, Intel