From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 13 Jan 2016 14:09:05 +0100
Subject: ptrace: don't open IRQs in ptrace_freeze_traced() too early

In the non-RT case the spin_lock_irq() here disables interrupts as well
as raw_spin_lock_irq(). So in the unlock case the interrupts are enabled
too early. 

Reported-by: kernel test robot <ying.huang@linux.intel.com>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/ptrace.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -128,12 +128,14 @@ static bool ptrace_freeze_traced(struct
 
 	spin_lock_irq(&task->sighand->siglock);
 	if (task_is_traced(task) && !__fatal_signal_pending(task)) {
-		raw_spin_lock_irq(&task->pi_lock);
+		unsigned long flags;
+
+		raw_spin_lock_irqsave(&task->pi_lock, flags);
 		if (task->state & __TASK_TRACED)
 			task->state = __TASK_TRACED;
 		else
 			task->saved_state = __TASK_TRACED;
-		raw_spin_unlock_irq(&task->pi_lock);
+		raw_spin_unlock_irqrestore(&task->pi_lock, flags);
 		ret = true;
 	}
 	spin_unlock_irq(&task->sighand->siglock);