linux-kernel - Re: rtmutex, pi_blocked_on, and blk_flush

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Message-ID: <Y+5GScI95xYeQPvf@linutronix.de>
Date:   Thu, 16 Feb 2023 16:05:45 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Crystal Wood <swood@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        John Keeping <john@...anate.com>,
        linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: rtmutex, pi_blocked_on, and blk_flush_plug()

On 2023-02-16 15:18:03 [+0100], To Crystal Wood wrote:
> On 2023-02-09 22:31:57 [-0600], Crystal Wood wrote:
> > Hello!
Hi,

> - spinlock_t invokes schedule_rtlock() which avoids sched_submit_work().
>   This is the behaviour as with !RT because it spins and does not submit
>   work either.
>   rwlock_t should be have the same way but invokes schedule() instead.
>   This looks wrong. And it could deadlock in sched_submit_work().

I have to correct myself. Also for rwlock_t it uses schedule_rtlock()
which means it does not invoke sched_submit_work().

There there I don't expect any deadlock here.

> > -Crystal

Sebastian