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From:   Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
To:     xiaolinkui <xiaolinkui@kylinos.cn>, "hch@lst.de" <hch@lst.de>,
        "sagi@grimberg.me" <sagi@grimberg.me>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: [PATCH] nvme: target: use struct_size() in kmalloc()
Thread-Topic: [PATCH] nvme: target: use struct_size() in kmalloc()
Thread-Index: AQHVDH8oTBY/BlMzjUaR4gerzBgDxQ==
Date:   Fri, 17 May 2019 16:32:02 +0000
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If maintainers are okay with this then,=0A=
=0A=
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>=0A=
=0A=
On 5/17/19 12:07 AM, xiaolinkui wrote:=0A=
> Use struct_size() to keep code sample.=0A=
> One of the more common cases of allocation size calculations is finding=
=0A=
> the size of a structure that has a zero-sized array at the end, along=0A=
> with memory for some number of elements for that array. For example:=0A=
>=0A=
> struct foo {=0A=
>     int stuff;=0A=
>     struct boo entry[];=0A=
> };=0A=
>=0A=
> instance =3D kmalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP=
_KERNEL);=0A=
>=0A=
> Instead of leaving these open-coded and prone to type mistakes, we can=0A=
> now use the new struct_size() helper:=0A=
>=0A=
> instance =3D kmalloc(struct_size(instance, entry, count), GFP_KERNEL);=0A=
>=0A=
> Signed-off-by: xiaolinkui <xiaolinkui@kylinos.cn>=0A=
> ---=0A=
>  drivers/nvme/target/admin-cmd.c | 4 ++--=0A=
>  1 file changed, 2 insertions(+), 2 deletions(-)=0A=
>=0A=
> diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-=
cmd.c=0A=
> index 9f72d51..6f9f830 100644=0A=
> --- a/drivers/nvme/target/admin-cmd.c=0A=
> +++ b/drivers/nvme/target/admin-cmd.c=0A=
> @@ -248,8 +248,8 @@ static void nvmet_execute_get_log_page_ana(struct nvm=
et_req *req)=0A=
>  	u16 status;=0A=
>  =0A=
>  	status =3D NVME_SC_INTERNAL;=0A=
> -	desc =3D kmalloc(sizeof(struct nvme_ana_group_desc) +=0A=
> -			NVMET_MAX_NAMESPACES * sizeof(__le32), GFP_KERNEL);=0A=
> +	desc =3D kmalloc(struct_size(desc, nsids, NVMET_MAX_NAMESPACES),=0A=
> +			GFP_KERNEL);=0A=
>  	if (!desc)=0A=
>  		goto out;=0A=
>  =0A=
=0A=
=0A=