Re: [PATCH -next] tpm: Use kzalloc for allocating only one thing

From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Zheng Yongjun <zhengyongjun3@huawei.com>,
	peterhuewe@gmx.de, jarkko@kernel.org,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: jgg@ziepe.ca
Subject: Re: [PATCH -next] tpm: Use kzalloc for allocating only one thing
Date: Tue, 29 Dec 2020 08:23:49 -0800	[thread overview]
Message-ID: <788cb2e68b98513c84cdc186923f7f99eb55b983.camel@HansenPartnership.com> (raw)
In-Reply-To: <20201229135154.23648-1-zhengyongjun3@huawei.com>

On Tue, 2020-12-29 at 21:51 +0800, Zheng Yongjun wrote:
> Use kzalloc rather than kcalloc(1,...)
> 
> The semantic patch that makes this change is as follows:
> (http://coccinelle.lip6.fr/)

What's the reason for wanting to do this transformation?

>  drivers/char/tpm/tpm1-cmd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-
> cmd.c
> index ca7158fa6e6c..4d8415e3b778 100644
> --- a/drivers/char/tpm/tpm1-cmd.c
> +++ b/drivers/char/tpm/tpm1-cmd.c
> @@ -794,7 +794,7 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32
> tpm_suspend_pcr)
>   */
>  int tpm1_get_pcr_allocation(struct tpm_chip *chip)
>  {
> -	chip->allocated_banks = kcalloc(1, sizeof(*chip-
> >allocated_banks),
> +	chip->allocated_banks = kzalloc(sizeof(*chip->allocated_banks),
>  					GFP_KERNEL);
>  	if (!chip->allocated_banks)
>  		return -ENOMEM;

The reason tpm1 has this is because it mirrors the allocation in tpm2
so we retain code consistency.  It's a fairly minor advantage, so it
could be changed if you have a better rationale ... but what is it?

James