linux-kernel - Re: [patch 15/63] locking: Add base code for RT rw

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Date:   Thu, 5 Aug 2021 10:59:02 -0400
From:   Waiman Long <llong@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Waiman Long <llong@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Will Deacon <will@...nel.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Davidlohr Bueso <dave@...olabs.net>
Subject: Re: [patch 15/63] locking: Add base code for RT rw_semaphore and
 rwlock

On 8/5/21 5:04 AM, Thomas Gleixner wrote:
> On Wed, Aug 04 2021 at 15:37, Waiman Long wrote:
>> On 7/30/21 9:50 AM, Thomas Gleixner wrote:
>>> +static int __sched rwbase_write_lock(struct rwbase_rt *rwb,
>>> +				     unsigned int state)
>>> +{
>>> +	struct rt_mutex_base *rtm = &rwb->rtmutex;
>>> +	unsigned long flags;
>>> +
>>> +	/* Take the rtmutex as a first step */
>>> +	if (rwbase_rtmutex_lock_state(rtm, state))
>> This function is used here before it was defined in next patch (patch 16).
> Correct and there are more I think. But that's a hen and egg
> problem:
>
> The base code cannot be compiled without the actual implementation for
> either rw_semaphore or rw_lock substitutions. The implementations cannot
> be compiled without the base code.
>
> So I chose to split it up so the base logic is separate.
>
> Thanks,
>
I realize that after the fact that the code introduced by this patch 
won't be compiled until the later patch is merged. So it is all OK.

Thanks,
Longman