Re: [PATCH] ext4: hash: change kzalloc(n * sizeof, ...) to kcalloc(n, sizeof, ...)

[Andreas Dilger]

On Mar 15, 2025, at 9:28 PM, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> 
> On Sat, Mar 15, 2025 at 12:29:34PM -0400, Ethan Carter Edwards wrote:
>> Open coded arithmetic in allocator arguments is discouraged. Helper
>> functions like kcalloc are preferred.
> 
> Well, yes, but ...
> 
>> +++ b/fs/ext4/hash.c
>> @@ -302,7 +302,7 @@ int ext4fs_dirhash(const struct inode *dir, const char *name, int len,
>> 
>> 	if (len && IS_CASEFOLDED(dir) &&
>> 	   (!IS_ENCRYPTED(dir) || fscrypt_has_encryption_key(dir))) {
>> -		buff = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL);
>> +		buff = kcalloc(PATH_MAX, sizeof(char), GFP_KERNEL);
> 
> sizeof(char) is defined to be 1.  So this should just be
> kzalloc(PATH_MAX, GFP_KERNEL).

I was going to say exactly the same thing.
Passing "1" to kcalloc() is just pure overhead.

Cheers, Andreas

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