restart_block: Prepare the ground for dumping timeout

Submitted by Jann Horn via Containers on Sept. 9, 2019, 10:23 a.m.

Details

Reviewer None
Submitted Sept. 9, 2019, 10:23 a.m.
Last Updated Sept. 9, 2019, 8:25 p.m.
Revision 1

Cover Letter

Hi,

I'm trying to address an issue in CRIU (Checkpoint Restore In Userspace)
about timed syscalls restart. It's not possible to use restart_syscall()
as the majority of applications does, as after restore the kernel doesn't
know anything about a syscall that may have been interrupted on
checkpoint. That's because the tasks are re-created from scratch and so
there isn't task_struct::restart_block set on a new task.

As a preparation, unify timeouts for different syscalls in
restart_block.

On contrary, I'm struggling with patches that introduce the new ptrace()
request API. I'll speak about difficulties of designing new ptrace
operation on Containers Microconference at Plumbers [with a hope to
find the sensible solution].

Cc: Adrian Reber <adrian@lisas.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: containers@lists.linux-foundation.org
Cc: linux-fsdevel@vger.kernel.org

Dmitry Safonov (9):
  futex: Remove unused uaddr2 in restart_block
  restart_block: Prevent userspace set part of the block
  select: Convert __esimate_accuracy() to ktime_t
  select: Micro-optimise __estimate_accuracy()
  select: Convert select_estimate_accuracy() to take ktime_t
  select: Extract common code into do_sys_ppoll()
  select: Use ktime_t in do_sys_poll() and do_poll()
  select/restart_block: Convert poll's timeout to u64
  restart_block: Make common timeout

 fs/eventpoll.c                 |   4 +-
 fs/select.c                    | 214 ++++++++++++---------------------
 include/linux/poll.h           |   2 +-
 include/linux/restart_block.h  |  11 +-
 kernel/futex.c                 |  14 +--
 kernel/time/alarmtimer.c       |   6 +-
 kernel/time/hrtimer.c          |  14 ++-
 kernel/time/posix-cpu-timers.c |  10 +-
 kernel/time/posix-stubs.c      |   8 +-
 kernel/time/posix-timers.c     |   8 +-
 10 files changed, 115 insertions(+), 176 deletions(-)
  

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