linux-kernel - Re: [PATCH rcu] srcu: Guarantee non-negative return value from srcu_read

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZxdPN6wT1LMyLaNL@infradead.org>
Date: Tue, 22 Oct 2024 00:07:35 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Christoph Hellwig <hch@...radead.org>,
	"Paul E. McKenney" <paulmck@...nel.org>, rcu@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-team@...a.com,
	rostedt@...dmis.org, andrii@...nel.org
Subject: Re: [PATCH rcu] srcu: Guarantee non-negative return value from
 srcu_read_lock()

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.