* Re: [PATCH v2 2/6] userfaultfd: add /dev/userfaultfd for fine grained access control
[not found] ` <20220422212945.2227722-3-axelrasmussen@google.com>
@ 2022-04-25 20:32 ` Dmitry V. Levin
2022-04-26 16:00 ` Axel Rasmussen
0 siblings, 1 reply; 3+ messages in thread
From: Dmitry V. Levin @ 2022-04-25 20:32 UTC (permalink / raw)
To: Axel Rasmussen
Cc: Alexander Viro, Andrew Morton, Charan Teja Reddy, Dave Hansen,
Gleb Fotengauer-Malinovskiy, Hugh Dickins, Jan Kara,
Jonathan Corbet, Mel Gorman, Mike Kravetz, Mike Rapoport,
Nadav Amit, Peter Xu, Shuah Khan, Suren Baghdasaryan,
Vlastimil Babka, zhangyi, linux-api, linux-doc, linux-fsdevel,
linux-kernel, linux-mm, linux-kselftest
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?
--
ldv
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2 2/6] userfaultfd: add /dev/userfaultfd for fine grained access control
2022-04-25 20:32 ` [PATCH v2 2/6] userfaultfd: add /dev/userfaultfd for fine grained access control Dmitry V. Levin
@ 2022-04-26 16:00 ` Axel Rasmussen
2022-04-26 17:13 ` Arnd Bergmann
0 siblings, 1 reply; 3+ messages in thread
From: Axel Rasmussen @ 2022-04-26 16:00 UTC (permalink / raw)
To: Dmitry V. Levin
Cc: Alexander Viro, Andrew Morton, Charan Teja Reddy, Dave Hansen,
Gleb Fotengauer-Malinovskiy, Hugh Dickins, Jan Kara,
Jonathan Corbet, Mel Gorman, Mike Kravetz, Mike Rapoport,
Nadav Amit, Peter Xu, Shuah Khan, Suren Baghdasaryan,
Vlastimil Babka, zhangyi, linux-api, linux-doc, linux-fsdevel,
LKML, Linux MM, Linuxkselftest
You're right, [1] says _IO is appropriate for ioctls which only take
an integer argument. I'll send a v3 with this fix, although I might
wait a bit for any other review comments before doing so. Thanks for
taking a look!
https://www.kernel.org/doc/html/latest/driver-api/ioctl.html
On Mon, Apr 25, 2022 at 1:32 PM Dmitry V. Levin <ldv@altlinux.org> wrote:
>
> 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?
>
>
> --
> ldv
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2 2/6] userfaultfd: add /dev/userfaultfd for fine grained access control
2022-04-26 16:00 ` Axel Rasmussen
@ 2022-04-26 17:13 ` Arnd Bergmann
0 siblings, 0 replies; 3+ messages in thread
From: Arnd Bergmann @ 2022-04-26 17:13 UTC (permalink / raw)
To: Axel Rasmussen
Cc: Dmitry V. Levin, Alexander Viro, Andrew Morton, Charan Teja Reddy,
Dave Hansen, Gleb Fotengauer-Malinovskiy, Hugh Dickins, Jan Kara,
Jonathan Corbet, Mel Gorman, Mike Kravetz, Mike Rapoport,
Nadav Amit, Peter Xu, Shuah Khan, Suren Baghdasaryan,
Vlastimil Babka, zhangyi, Linux API, open list:DOCUMENTATION,
Linux FS-devel Mailing List, LKML, Linux MM, Linuxkselftest
On Tue, Apr 26, 2022 at 6:00 PM Axel Rasmussen <axelrasmussen@google.com> wrote:
>
> You're right, [1] says _IO is appropriate for ioctls which only take
> an integer argument. I'll send a v3 with this fix, although I might
> wait a bit for any other review comments before doing so. Thanks for
> taking a look!
If there are no other command codes, you could also set .compat_ioctl
to the same function pointer as .unlocked_ioctl, the compat_ptr_ioctl
conversion is only needed when there are commands that take a pointer.
Armd
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] ` <20220422212945.2227722-3-axelrasmussen@google.com>
2022-04-25 20:32 ` [PATCH v2 2/6] userfaultfd: add /dev/userfaultfd for fine grained access control Dmitry V. Levin
2022-04-26 16:00 ` Axel Rasmussen
2022-04-26 17:13 ` Arnd Bergmann
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