linux-kernel - Re: [patch V3 15/64] rtmutex: Provide rt_mutex_base_is

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Message-ID: <87fsviudj4.ffs@tglx>
Date:   Mon, 09 Aug 2021 12:18:39 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Davidlohr Bueso <dave@...olabs.net>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        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>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Mike Galbraith <efault@....de>
Subject: Re: [patch V3 15/64] rtmutex: Provide rt_mutex_base_is_locked()

On Sun, Aug 08 2021 at 13:41, Davidlohr Bueso wrote:
>>+/**
>>+ * rt_mutex_base_is_locked - is the rtmutex locked
>>+ * @lock: the mutex to be queried
>>+ *
>>+ * Returns true if the mutex is locked, false if unlocked.
>>+ */
>>+static inline bool rt_mutex_base_is_locked(struct rt_mutex_base *lock)
>>+{
>>+	return lock->owner != NULL;
>
> Does this want to be READ_ONCE()? While not a big deal because
> it's ultimately only used by drm debugging, I don't see any harm
> in avoiding potential tearing.

Makes sense.