On 20.06.22 01:34, Nadav Amit wrote:
> From: Nadav Amit <namit@xxxxxxxxxx>
>
> As the next patches are going to introduce more information that needs
> to be propagated regarding handled user requests, introduce uffd_flags
> that would be used to propagate this information.
>
> Remove the unused UFFD_FLAGS_SET to avoid confusion in the constant
> names.
>
> Introducing uffd flags also allows to avoid mm/userfaultfd from being
> using uapi (e.g., UFFDIO_COPY_MODE_WP).
>
> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
> Cc: Peter Xu <peterx@xxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>
> ---
> fs/userfaultfd.c | 20 +++++++++----
> include/linux/hugetlb.h | 4 +--
> include/linux/shmem_fs.h | 8 ++++--
> include/linux/userfaultfd_k.h | 23 +++++++++------
> mm/hugetlb.c | 3 +-
> mm/shmem.c | 6 ++--
> mm/userfaultfd.c | 53 ++++++++++++++++++-----------------
> 7 files changed, 68 insertions(+), 49 deletions(-)
>
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index d398f6bf6d74..5daafa54eb3f 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -1700,6 +1700,8 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
> struct uffdio_copy uffdio_copy;
> struct uffdio_copy __user *user_uffdio_copy;
> struct userfaultfd_wake_range range;
> + bool mode_wp;
> + uffd_flags_t uffd_flags;
>
> user_uffdio_copy = (struct uffdio_copy __user *) arg;
>
> @@ -1726,10 +1728,15 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
> goto out;
> if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP))
> goto out;
> +
> + mode_wp = uffdio_copy.mode & UFFDIO_COPY_MODE_WP;
> +
> + uffd_flags = mode_wp ? UFFD_FLAGS_WP : 0;
why not simply
uffd_flags = 0;
if (uffdio_copy.mode & UFFDIO_COPY_MODE_WP)
uffd_flags |= UFFD_FLAGS_WP;
?
[...]
> index eee374c29c85..6331148023c1 100644
> --- a/include/linux/userfaultfd_k.h
> +++ b/include/linux/userfaultfd_k.h
> @@ -34,7 +34,6 @@
> #define UFFD_NONBLOCK O_NONBLOCK
>
> #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
> -#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
>
> extern int sysctl_unprivileged_userfaultfd;
>
> @@ -56,23 +55,29 @@ enum mcopy_atomic_mode {
> MCOPY_ATOMIC_CONTINUE,
> };
>
> +typedef unsigned int __bitwise uffd_flags_t;
> +
Instead of using 0 when no flags are defined, add
#define UFFD_FLAGS_NONE ((__force uffd_flags_t)0)
which makes it easier to understand at callsites what's happening
Apart from these two things
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
--
Thanks,
David / dhildenb
