Re: [Ocfs2-devel] [PATCH 1/1 linux-next] ocfs2: remove unnecessary sizeof(char)

[Rasmus Villemoes <linux@rasmusvillemoes.dk>]

On Mon, Dec 22 2014, Andrew Morton <akpm@linux-foundation.org> wrote:

> On Mon, 22 Dec 2014 20:05:09 +0100 Fabian Frederick <fabf@skynet.be> wrote:
>
>>  
>> -	replay_map = kzalloc(sizeof(struct ocfs2_replay_map) +
>> -			     (osb->max_slots * sizeof(char)), GFP_KERNEL);
>> +	replay_map = kzalloc(sizeof(struct ocfs2_replay_map) + osb->max_slots,
>> +			     GFP_KERNEL);
>>  
>
> I dunno.  The code at present isn't particularly idiomatic, but it has
> some documentation value and says "I know what I'm doing".
>
> It would be better if it was
>
> 	kzalloc(sizeof(struct ocfs2_replay_map) *
> 		sizeof(struct ocfs2_replay_map.rm_replay_slots[0]), ...);
>
> And it would be better if C permitted that ;)
>
> 	kzalloc(sizeof(struct ocfs2_replay_map) *
> 		sizeof((struct ocfs2_replay_map *)0)->rm_replay_slots[0]), ...);
>
> yuk.

Well, the yuckiness could be hidden behind FIELD_SIZEOF. CodingStyle
explicitly mentions that macro. No opinion on whether it's worth it in
this case.

Rasmus