Received-SPF: pass (google.com: domain of linux-kernel+bounces-203453-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Precedence: bulk
MIME-Version: 1.0
References: <20240605135245.14921-1-cuitao@kylinos.cn>
In-Reply-To: <20240605135245.14921-1-cuitao@kylinos.cn>
From: Jason Wang <jasowang@redhat.com>
Date: Thu, 6 Jun 2024 08:29:30 +0800
Message-ID: <CACGkMEvB4MoGqqOLvNyY8css8kq56-D5J2M4VZCM1AfGCojiRw@mail.gmail.com>
Subject: Re: [PATCH] tools/virtio: Use the __GFP_ZERO flag of kmalloc to
 complete the memory initialization.
To: cuitao <cuitao@kylinos.cn>
Cc: mst@redhat.com, virtualization@lists.linux.dev, xuanzhuo@linux.alibaba.com, 
	eperezma@redhat.com, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Wed, Jun 5, 2024 at 9:56=E2=80=AFPM cuitao <cuitao@kylinos.cn> wrote:
>
> Use the __GFP_ZERO flag of kmalloc to initialize memory while allocating =
it,
> without the need for an additional memset call.
>
> Signed-off-by: cuitao <cuitao@kylinos.cn>
> ---
>  tools/virtio/linux/kernel.h | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/tools/virtio/linux/kernel.h b/tools/virtio/linux/kernel.h
> index 6702008f7f5c..9e401fb7c215 100644
> --- a/tools/virtio/linux/kernel.h
> +++ b/tools/virtio/linux/kernel.h
> @@ -66,10 +66,7 @@ static inline void *kmalloc_array(unsigned n, size_t s=
, gfp_t gfp)
>
>  static inline void *kzalloc(size_t s, gfp_t gfp)
>  {
> -       void *p =3D kmalloc(s, gfp);
> -
> -       memset(p, 0, s);
> -       return p;
> +       return kmalloc(s, gfp | __GFP_ZERO);
>  }
>
>  static inline void *alloc_pages_exact(size_t s, gfp_t gfp)
> --
> 2.25.1
>

Does this really work?

extern void *__kmalloc_fake, *__kfree_ignore_start, *__kfree_ignore_end;
static inline void *kmalloc(size_t s, gfp_t gfp)
{
  if (__kmalloc_fake)
                return __kmalloc_fake;
        return malloc(s);
}

Thanks