linux-kernel - Re: [lkp] [ptrace] 63a745aa6a: inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.

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Date:	Wed, 13 Jan 2016 14:27:39 +0100
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	kernel test robot <ying.huang@...ux.intel.com>
Cc:	lkp@...org, LKML <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [lkp] [ptrace] 63a745aa6a: inconsistent {HARDIRQ-ON-W} ->
 {IN-HARDIRQ-W} usage.

Subject: [PATCH RT] 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@...ux.intel.com>
Cc: stable-rt@...r.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/ptrace.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index d1d158005ad0..2856b433d9d6 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -129,12 +129,14 @@ static bool ptrace_freeze_traced(struct task_struct *task)
 
 	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);
-- 
2.7.0.rc3