Re: [PATCH v7] mm: cma: support sysfs

[Dmitry Osipenko]

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
a good coding style. Otherwise there is no point in not embedding kobj
into cma struct as well, IMO.