lkml.org 
[lkml]   [2020]   [Jul]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC v2 0/4] futex2: Add new futex interface
    Hello.

    On 09.07.2020 19:59, André Almeida wrote:
    > This RFC is a followup to the previous discussion initiated from my
    > last
    > patch "futex: Implement mechanism to wait on any of several
    > futexes"[1].
    > As stated in the thread, the correct approach to move forward with the
    > wait multiple operation would be to create a new syscall that would
    > have
    > all new cool features.
    >
    > The first patch adds the new interface and just translate the call for
    > the old interface, without implementing new features. The goal here is
    > to establish the interface and to check if everyone is happy with this
    > API. The rest of patches are selftests to show the interface in action.
    > I have the following questions:
    >
    > - What suggestions do you have to implement this? Start from scratch or
    > reuse the most code possible?
    >
    > - The interface seems correct and implements the requirements asked by
    > you?
    >
    > Those are the cool new features that this syscall should address some
    > day:
    >
    > - Operate with variable bit size futexes, not restricted to 32:
    > 8, 16 and 64
    >
    > - Wait on multiple futexes, using the following semantics:
    >
    > struct futex_wait {
    > void *uaddr;
    > unsigned long val;
    > unsigned long flags;
    > };
    >
    > sys_futex_waitv(struct futex_wait *waiters, unsigned int nr_waiters,
    > unsigned long flags, struct __kernel_timespec *timo);
    >
    > - Have NUMA optimizations: if FUTEX_NUMA_FLAG is set, the `void *uaddr`
    > argument won't be a value of type u{8, 16, 32, 64} anymore, but a
    > struct
    > containing a NUMA node hint:
    >
    > struct futex32_numa {
    > u32 value __attribute__ ((aligned (8)));
    > u32 hint;
    > };
    >
    > struct futex64_numa {
    > u64 value __attribute__ ((aligned (16)));
    > u64 hint;
    > };
    >
    > Thanks,
    > André
    >
    > Changes since v1:
    > - The timeout argument now uses __kernel_timespec as type
    > - time32 interface was removed
    > v1: https://lore.kernel.org/patchwork/cover/1255437/
    >
    > [1] https://lore.kernel.org/patchwork/patch/1194339/
    >
    > André Almeida (4):
    > futex2: Add new futex interface
    > selftests: futex: Add futex2 wake/wait test
    > selftests: futex: Add futex2 timeout test
    > selftests: futex: Add futex2 wouldblock test
    >
    > MAINTAINERS | 2 +-
    > arch/x86/entry/syscalls/syscall_32.tbl | 2 +
    > arch/x86/entry/syscalls/syscall_64.tbl | 2 +
    > include/linux/syscalls.h | 7 ++
    > include/uapi/asm-generic/unistd.h | 8 +-
    > include/uapi/linux/futex.h | 10 ++
    > init/Kconfig | 7 ++
    > kernel/Makefile | 1 +
    > kernel/futex2.c | 73 ++++++++++++
    > kernel/sys_ni.c | 4 +
    > tools/include/uapi/asm-generic/unistd.h | 7 +-
    > .../selftests/futex/functional/.gitignore | 1 +
    > .../selftests/futex/functional/Makefile | 4 +-
    > .../selftests/futex/functional/futex2_wait.c | 111 ++++++++++++++++++
    > .../futex/functional/futex_wait_timeout.c | 38 ++++--
    > .../futex/functional/futex_wait_wouldblock.c | 33 +++++-
    > .../testing/selftests/futex/functional/run.sh | 3 +
    > .../selftests/futex/include/futex2test.h | 77 ++++++++++++
    > 18 files changed, 373 insertions(+), 17 deletions(-)
    > create mode 100644 kernel/futex2.c
    > create mode 100644
    > tools/testing/selftests/futex/functional/futex2_wait.c
    > create mode 100644 tools/testing/selftests/futex/include/futex2test.h

    What branch/tag this submission is based on please? It seems it is not a
    5.8 but rather 5.7 since the second patch misses faccessat2() syscall
    and fails to be applied cleanly.

    Thanks.

    --
    Oleksandr Natalenko (post-factum)

    \
     
     \ /
      Last update: 2020-07-10 15:34    [W:2.852 / U:0.628 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site