linux-kernel - Re: [PATCH v4 06/13] riscv: Improve zacas fully-ordered cmpxchg()

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: <ZqoTEk2zMohhog1Z@andrea>
Date: Wed, 31 Jul 2024 12:33:54 +0200
From: Andrea Parri <parri.andrea@...il.com>
To: Andrew Jones <ajones@...tanamicro.com>
Cc: Alexandre Ghiti <alexghiti@...osinc.com>,
	Jonathan Corbet <corbet@....net>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, Conor Dooley <conor@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>, Boqun Feng <boqun.feng@...il.com>,
	Arnd Bergmann <arnd@...db.de>, Leonardo Bras <leobras@...hat.com>,
	Guo Ren <guoren@...nel.org>, linux-doc@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org, linux-arch@...r.kernel.org,
	Andrea Parri <andrea@...osinc.com>
Subject: Re: [PATCH v4 06/13] riscv: Improve zacas fully-ordered cmpxchg()

> >   amocas.X.aqrl   a5,a4,(s1)
> 
> We won't get release semantics if the exchange fails. Does that matter?

Conditional (atomic) RMW operations are unordered/relaxed on failure, so
we should be okay here; cf. e.g. Documentation/atomic_t.txt.

  Andrea