linux-kernel - Re: [PATCH v2 1/3] rtmutex: update rt-mutex-design

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Date:   Mon, 24 Apr 2017 21:45:20 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        "open list:LOCKING PRIMITIVES" <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Siewior <bigeasy@...utronix.de>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 1/3] rtmutex: update rt-mutex-design

          structure holds a pointer to the task, as well as the mutex that
>> -           the task is blocked on.  It also has the plist node structures to
>> -           place the task in the waiter_list of a mutex as well as the
>> -           pi_list of a mutex owner task (described below).
>> +          the task is blocked on.  It also has a rbtree node structures to
> 
> Here I assume we are talking about struct rt_mutex_waiter[1].  If so I
> suggest to replace rbtree with rb_node.

They are the same thing here, rbtree node and rb_node. :)

> 
>> +          place the task in waiters rbtree of a mutex as well as the
>> +          pi_waiters rbtree of a mutex owner task (described below).
> 
> Also following the comment for @pi_tree_entry, s/"a mutex owner
> task"/"a mutex owner waiters tree" .

As my understand, pi_waiters is in task structure. We refer to what's
the pi_tree_entry in.

> 
> [1]. http://lxr.free-electrons.com/source/kernel/locking/rtmutex_common.h#L25
> 
> 
>> -
>> +If the G process has highest priority in the chain, then all the tasks up
> 
> If process G has the highest priority in the chain, ...

Sounds better. Thanks!
>> +mutex (waiter "task" field is not NULL), then we go to sleep (call schedule)
>> +
> 
> This change was likely not done on purpose.

Yes. Thanks.
>