ptrace_stop() has some complicated checks to prevent the scheduling in the
TASK_TRACED state with the pending SIGKILL, but these checks are racy, and
they depend on arch_ptrace_stop_needed().
This patch assumes that the traced task should die asap if it was killed by
SIGKILL, in that case schedule()->signal_pending_state() should respect the
TASK_WAKEKILL part of TASK_TRACED, and we can kill this nasty special case.
Note: do_exit()->ptrace_notify() is special, the killed task can already
dequeue SIGKILL at this point. Another indication that fatal_signal_pending()
is not exactly right.
Signed-off-by: Oleg Nesterov <[email protected]>
--- 26-rc2/include/linux/sched.h~1_KILL_TRACED_CHECK 2008-06-01 16:44:39.000000000 +0400
+++ 26-rc2/include/linux/sched.h 2008-06-01 16:44:39.000000000 +0400
@@ -2034,9 +2034,6 @@ static inline int signal_pending_state(l
if (!signal_pending(p))
return 0;
- if (state & (__TASK_STOPPED | __TASK_TRACED))
- return 0;
-
return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
}