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

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

[Fabian Frederick]

sizeof(char) is always 1.

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
---
 fs/ocfs2/journal.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index e238bbc..750597c 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -129,8 +129,8 @@ int ocfs2_compute_replay_slots(struct ocfs2_super *osb)
 	if (osb->replay_map)
 		return 0;
 
-	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);
 
 	if (!replay_map) {
 		mlog_errno(-ENOMEM);
-- 
1.9.1

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

[Andrew Morton]

On Mon, 22 Dec 2014 20:05:09 +0100 Fabian Frederick <fabf@skynet.be> wrote:

> sizeof(char) is always 1.
> 
> ...
>
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -129,8 +129,8 @@ int ocfs2_compute_replay_slots(struct ocfs2_super *osb)
>  	if (osb->replay_map)
>  		return 0;
>  
> -	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);
>  
>  	if (!replay_map) {
>  		mlog_errno(-ENOMEM);

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.

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

[Rasmus Villemoes]

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