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Subject: Re: [PATCH v7] mm: cma: support sysfs
To:     John Hubbard <jhubbard@nvidia.com>,
        Minchan Kim <minchan@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
        gregkh@linuxfoundation.org, surenb@google.com, joaodias@google.com,
        willy@infradead.org, Colin Ian King <colin.king@canonical.com>
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From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <8f147942-9a94-1e36-b608-4dd883af29b1@gmail.com>
Date:   Thu, 25 Mar 2021 01:42:12 +0300
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25.03.2021 01:23, John Hubbard пишет:
> On 3/24/21 3:11 PM, Dmitry Osipenko wrote:
>> 25.03.2021 01:01, John Hubbard пишет:
>>> On 3/24/21 2:31 PM, Dmitry Osipenko wrote:
>>>> ...
>>>>> +#include <linux/kobject.h>
>>>>> +
>>>>> +struct cma_kobject {
>>>>> +    struct cma *cma;
>>>>> +    struct kobject kobj;
>>>>
>>>> If you'll place the kobj as the first member of the struct, then
>>>> container_of will be a no-op.
>>>>
>>>
>>> However, *this does not matter*. Let's not get carried away. If
>>> container_of() ends up as a compile-time addition of +8, instead
>>> of +0, there is not going to be a visible effect in the world.
>>> Or do you have some perf data to the contrary?
>>>
>>> Sometimes these kinds of things matter. But other times, they are
>>> just pointless to fret about, and this is once such case.
>>
>> Performance is out of question here, my main point is about maintaining
> 
> In that case, there is even less reason to harass people about the order
> of members of a struct.
> 
>> a good coding style. Otherwise there is no point in not embedding kobj
>> into cma struct as well, IMO.
> 
> 
> We really don't need to worry about the order of members in a struct,
> from a "coding style" point of view. It is a solid step too far.
> 
> Sorry if that sounds a little too direct. But this review has tended to
> go quite too far into nitpicks that are normally left as-is, and I've
> merely picked one that is particularly questionable. I realize that other
> coding communities have their own standards. Here, I'm explaining what
> I have observed about linux-mm and linux-kernel, which needs to be
> respected.

I tried to help as much as I could, sorry if this felt annoying to you
or anyone else.

I assume that linux-mm maintainers, like any other maintainers, should
skip all suggestions that are deemed as inappropriate to them.