linux-kernel - Re: [PATCH v10 01/21] rcuref: Provide rcuref_is

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Message-ID: <20250314103630.GM19344@noisy.programming.kicks-ass.net>
Date: Fri, 14 Mar 2025 11:36:30 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-kernel@...r.kernel.org,
	André Almeida <andrealmeid@...lia.com>,
	Darren Hart <dvhart@...radead.org>,
	Davidlohr Bueso <dave@...olabs.net>, Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Waiman Long <longman@...hat.com>
Subject: Re: [PATCH v10 01/21] rcuref: Provide rcuref_is_dead().

On Wed, Mar 12, 2025 at 04:16:14PM +0100, Sebastian Andrzej Siewior wrote:

> +/**
> + * rcuref_is_dead -	Check if the rcuref has been already marked dead
> + * @ref:		Pointer to the reference count
> + *
> + * Return: True if the object has been marked DEAD. This signals that a previous
> + * invocation of rcuref_put() returned true on this reference counter meaning
> + * the protected object can safely be scheduled for deconstruction.
> + * Otherwise, returns false.
> + */
> +static inline bool rcuref_is_dead(rcuref_t *ref)
> +{
> +	unsigned int c = atomic_read(&ref->refcnt);
> +
> +	return (c >= RCUREF_RELEASED) && (c < RCUREF_NOREF);
> +}

I had to check, but yes, the compiler generates sane code for this.