Re: [PATCH v2 2/6] userfaultfd: add /dev/userfaultfd for fine grained access control

From: Dmitry V. Levin
Date: Mon Apr 25 2022 - 16:32:57 EST


On Fri, Apr 22, 2022 at 02:29:41PM -0700, Axel Rasmussen wrote:
[...]
> --- a/include/uapi/linux/userfaultfd.h
> +++ b/include/uapi/linux/userfaultfd.h
> @@ -12,6 +12,10 @@
>
> #include <linux/types.h>
>
> +/* ioctls for /dev/userfaultfd */
> +#define USERFAULTFD_IOC 0xAA
> +#define USERFAULTFD_IOC_NEW _IOWR(USERFAULTFD_IOC, 0x00, int)

Why this new ioctl is defined using _IOWR()? Since it neither reads from
user memory nor writes into user memory, it should rather be defined using
_IO(), shouldn't it?


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ldv