Messages in this thread | | | Date | Wed, 23 Jun 2021 05:42:12 +0300 | From | "Dmitry V. Levin" <> | Subject | Re: [PATCH v2] userfaultfd: fix UFFDIO_CONTINUE ioctl request definition |
| |
Hi,
On Tue, Jun 01, 2021 at 05:34:32PM +0300, Gleb Fotengauer-Malinovskiy wrote: > This ioctl request reads from uffdio_continue structure which justifies > _IOC_READ flag. > See NOTEs in include/uapi/asm-generic/ioctl.h for more information.
These ioctl flag usage rules seem to be a perpetual source of mistakes. I suggest a slightly different wording of the commit message which is hopefully a bit easier to follow:
"This ioctl request reads from uffdio_continue structure written by userspace which justifies _IOC_WRITE flag. It also writes back to that structure which justifies _IOC_READ flag.
See NOTEs in include/uapi/asm-generic/ioctl.h for more information."
Please make sure this patch is merged before v5.13 is released, otherwise the UAPI bug would have to stay for backwards ABI compatibility.
> Fixes: f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE ioctl") > Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org> > Acked-by: Peter Xu <peterx@redhat.com> > --- > include/uapi/linux/userfaultfd.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > v2 fix commit message > > diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h > index bafbeb1a2624..650480f41f1d 100644 > --- a/include/uapi/linux/userfaultfd.h > +++ b/include/uapi/linux/userfaultfd.h > @@ -80,8 +80,8 @@ > struct uffdio_zeropage) > #define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \ > struct uffdio_writeprotect) > -#define UFFDIO_CONTINUE _IOR(UFFDIO, _UFFDIO_CONTINUE, \ > - struct uffdio_continue) > +#define UFFDIO_CONTINUE _IOWR(UFFDIO, _UFFDIO_CONTINUE, \ > + struct uffdio_continue) > > /* read() structure */ > struct uffd_msg {
Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
-- ldv
| |