Messages in this thread Patch in this message | | | Date | Fri, 13 Feb 2009 11:54:42 +0100 | From | Oleg Nesterov <> | Subject | [PATCH -mm 2/2] ptrace_untrace: fix the SIGNAL_STOP_STOPPED check |
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This bug is ancient too. ptrace_untrace() must not resume the task if the group stop in progress, we should set TASK_STOPPED instead.
Unfortunately, we still have problems here:
- if the process/thread was traced, SIGNAL_STOP_STOPPED does not necessary means this thread group is stopped.
- ptrace breaks the bookkeeping of ->group_stop_count.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
--- 6.29-rc3/kernel/ptrace.c~2_FIX_STOPPED 2009-02-13 11:06:56.000000000 +0100 +++ 6.29-rc3/kernel/ptrace.c 2009-02-13 11:38:50.000000000 +0100 @@ -60,11 +60,15 @@ static void ptrace_untrace(struct task_s { spin_lock(&child->sighand->siglock); if (task_is_traced(child)) { - if (child->signal->flags & SIGNAL_STOP_STOPPED) { + /* + * If the group stop is completed or in progress, + * this thread was already counted as stopped. + */ + if (child->signal->flags & SIGNAL_STOP_STOPPED || + child->signal->group_stop_count) __set_task_state(child, TASK_STOPPED); - } else { + else signal_wake_up(child, 1); - } } spin_unlock(&child->sighand->siglock); }
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