Subject: Re: [PATCH v3 2/6] sched/rtmutex/deadline: Fix a PI crash for
 deadline tasks
References: <1460633827-345-1-git-send-email-xlpang@redhat.com>
 <1460633827-345-3-git-send-email-xlpang@redhat.com>
 <20160420131932.GC3430@twins.programming.kicks-ass.net>
 <571788F6.3020100@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Juri Lelli <juri.lelli@arm.com>, Ingo Molnar <mingo@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>
From: Xunlei Pang <xpang@redhat.com>
Message-ID: <571999D2.4090803@redhat.com>
Date: Fri, 22 Apr 2016 11:26:10 +0800
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Hi Peter,

On 2016/04/20 at 21:49, Xunlei Pang wrote:
> On 2016/04/20 at 21:19, Peter Zijlstra wrote:
>> On Thu, Apr 14, 2016 at 07:37:03PM +0800, Xunlei Pang wrote:
>>> +	/* Updated under pi_lock and rtmutex lock */
>>>  	struct rb_node *pi_waiters_leftmost;
>>> +	struct rb_node *pi_waiters_leftmost_copy;
>>>  struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
>>>  {
>>> +	if (!task->pi_waiters_leftmost_copy)
>>>  		return NULL;
>>>  
>>> +	return rb_entry(task->pi_waiters_leftmost_copy,
>>> +				struct rt_mutex_waiter, pi_tree_entry)->task;
>>>  }
>> why ?! Why not keep a regular task_struct pointer and avoid this stuff?
> I meant to make it semantically consistent, but I can change it since you think task_struct is better.

What do you think this version of PATCH1 and PATCH2?
If you are fine with it, I can sent it out as v4 separately, then we can focus on the issue in PATCH5.

Thanks!

>
> Regards,
> Xunlei