From: Christoph Hellwig <hch@infradead.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com, rostedt@goodmis.org, andrii@kernel.org
Subject: Re: [PATCH rcu] srcu: Guarantee non-negative return value from srcu_read_lock()
Date: Tue, 22 Oct 2024 00:07:35 -0700 [thread overview]
Message-ID: <ZxdPN6wT1LMyLaNL@infradead.org> (raw)
In-Reply-To: <20241022070635.GY16066@noisy.programming.kicks-ass.net>
On Tue, Oct 22, 2024 at 09:06:35AM +0200, Peter Zijlstra wrote:
> What is returned is an array index -- and SRCU is currently built using
> an array of size 2. Using larger arrays is conceivable (IIRC some
> versions of preemptible RCU used up to 4 or something).
>
> So while the values 0,1 are possible inside bool, that does not reflect
> the nature of the numbers, which is an array index. Mapping that onto
> bool would be slightly confusing (and limit possible future extention of
> using larger arrays for SRCU).
Ok, make sense. Maybe add this to the comment if we're updating іt.
But using an unsigned return value might still be useful.
next prev parent reply other threads:[~2024-10-22 7:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-21 22:13 [PATCH rcu] srcu: Guarantee non-negative return value from srcu_read_lock() Paul E. McKenney
2024-10-21 23:50 ` Andrii Nakryiko
2024-10-22 0:21 ` Paul E. McKenney
2024-10-22 2:01 ` Andrii Nakryiko
2024-10-22 3:30 ` Paul E. McKenney
2024-10-22 3:40 ` Andrii Nakryiko
2024-10-22 7:07 ` Peter Zijlstra
2024-10-22 14:27 ` Paul E. McKenney
2024-10-22 6:51 ` Christoph Hellwig
2024-10-22 7:06 ` Peter Zijlstra
2024-10-22 7:07 ` Christoph Hellwig [this message]
2024-10-22 7:10 ` Peter Zijlstra
2024-10-22 7:13 ` Christoph Hellwig
2024-10-22 14:26 ` Paul E. McKenney
2024-10-22 17:29 ` Andrii Nakryiko
2024-10-23 6:40 ` Christoph Hellwig
2024-10-23 16:34 ` Andrii Nakryiko
2024-10-23 16:46 ` Alan Huang
2024-10-23 16:59 ` Andrii Nakryiko
2024-10-23 6:58 ` Alan Huang
2024-10-23 16:40 ` Paul E. McKenney
2024-10-23 16:56 ` Alan Huang
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