[PATCH 0/12] ptrace: cleaning up ptrace_stop

Eric W. Biederman
2022-04-29T21:46:59Z

The states TASK_STOPPED and TASK_TRACE are special in they can not
handle spurious wake-ups. This plus actively depending upon and
changing the value of tsk->__state causes problems for PREEMPT_RT and
Peter's freezer rewrite.

There are a lot of details we have to get right to sort out the
technical challenges and this is my parred back version of the changes
that contains just those problems I see good solutions to that I believe
are ready.

In particular I don't have a solution that is ready for the challenges
presented by wait_task_inactive.

I hope we can review these changes and then have a firm foundation
for the rest of the challenges.

There are cleanups to the ptrace support for xtensa, um, and
ia64.

I have sucked in the first patch of Peter's freezer change as
with minor modifications I believe it is ready to go.

Eric W. Biederman (12):
signal: Rename send_signal send_signal_locked
signal: Replace __group_send_sig_info with send_signal_locked
ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP
ptrace/xtensa: Replace PT_SINGLESTEP with TIF_SINGLESTEP
signal: Use lockdep_assert_held instead of assert_spin_locked
ptrace: Reimplement PTRACE_KILL by always sending SIGKILL
ptrace: Don't change __state
ptrace: Remove arch_ptrace_attach
ptrace: Always take siglock in ptrace_resume
ptrace: Only return signr from ptrace_stop if it was provided
ptrace: Always call schedule in ptrace_stop
sched,signal,ptrace: Rework TASK_TRACED, TASK_STOPPED state

arch/ia64/include/asm/ptrace.h | 4 --
arch/ia64/kernel/ptrace.c | 57 ----------------
arch/um/include/asm/thread_info.h | 2 +
arch/um/kernel/exec.c | 2 +-
arch/um/kernel/process.c | 2 +-
arch/um/kernel/ptrace.c | 8 +--
arch/um/kernel/signal.c | 4 +-
arch/xtensa/kernel/ptrace.c | 4 +-
arch/xtensa/kernel/signal.c | 4 +-
drivers/tty/tty_jobctrl.c | 4 +-
include/linux/ptrace.h | 7 --
include/linux/sched.h | 10 ++-
include/linux/sched/jobctl.h | 10 +++
include/linux/sched/signal.h | 23 ++++++-
include/linux/signal.h | 3 +-
kernel/ptrace.c | 88 +++++++++----------------
kernel/signal.c | 135 +++++++++++++++++---------------------
kernel/time/posix-cpu-timers.c | 6 +-
18 files changed, 145 insertions(+), 228 deletions(-)

Eric