linux-kernel - Re: [PATCH 1/7] drivers/rtc/sysfs: move code to count_attribute

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Message-ID: <CAKPOu+_CEJH0zfk5PQU5dxFY8ZiYjFvvAG2GXPM_3Fr2_om8Xw@mail.gmail.com>
Date:   Mon, 9 Oct 2023 20:01:43 +0200
From:   Max Kellermann <max.kellermann@...os.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] drivers/rtc/sysfs: move code to count_attribute_groups()

On Mon, Oct 9, 2023 at 7:24 PM Greg KH <gregkh@...uxfoundation.org> wrote:
> What 3 different purposes?

The variable gets initialized 3 times with different (unrelated) values:

1. count old rtc->dev.groups
2. count grps
3. allocate new rtc->dev.groups

This coding style is confusing and error prone. The code gets simpler
with this patch, because the cognitive load of understanding a
"count_attribute_groups()" call is lower than reading the "while" loop
and figuring out why it's there.

But I really wrote this patch because after making "rtc->dev.groups"
const, I cannot any longer assign it to "groups", because that
variable must remain non-const.