ptrace: give more respect to SIGKILL

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() has no reason to
ignore 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]>
Cc: Ingo Molnar <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Oleg Nesterov 2008-07-25 01:47:36 -07:00 • committed by Linus Torvalds
commit 364d3c13c1

View file

@ -2054,9 +2054,6 @@ static inline int signal_pending_state(long state, struct task_struct *p)
if (!signal_pending(p))
return 0;
if (state & (__TASK_STOPPED | __TASK_TRACED))
return 0;
return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
}