Commit 1ee11844 authored Apr 02, 2009 by Oleg Nesterov Committed by Linus Torvalds Apr 02, 2009

ptrace_untrace: fix the SIGNAL_STOP_STOPPED check



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>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 95a3540d

kernel/ptrace.c

+7 −3

Original line number	Original line	Diff line number	Diff line
	@@ -60,12 +60,16 @@ static void ptrace_untrace(struct task_struct *child)
	{		{
	spin_lock(&child->sighand->siglock);		spin_lock(&child->sighand->siglock);
	if (task_is_traced(child)) {		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);		__set_task_state(child, TASK_STOPPED);
	} else {		else
	signal_wake_up(child, 1);		signal_wake_up(child, 1);
	}		}
	}
	spin_unlock(&child->sighand->siglock);		spin_unlock(&child->sighand->siglock);
	}		}