linux-kernel - Re: [RFC PATCH] LKMM: Add ctrl_dep() macro for control dependency

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: <1587674056.44794.1632946389244.JavaMail.zimbra@efficios.com>
Date:   Wed, 29 Sep 2021 16:13:09 -0400 (EDT)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Will Deacon <will@...nel.org>, paulmck <paulmck@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Segher Boessenkool <segher@...nel.crashing.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Andrea Parri <parri.andrea@...il.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Nicholas Piggin <npiggin@...il.com>,
        David Howells <dhowells@...hat.com>,
        j alglave <j.alglave@....ac.uk>,
        luc maranget <luc.maranget@...ia.fr>,
        akiyks <akiyks@...il.com>,
        linux-toolchains <linux-toolchains@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>
Subject: Re: [RFC PATCH] LKMM: Add ctrl_dep() macro for control dependency

----- On Sep 29, 2021, at 3:50 PM, Mathieu Desnoyers mathieu.desnoyers@...icios.com wrote:

[...]

> void fct(void)
> {
>    int x;
> 
>    if (refcount_dec_and_test()) {
>        var1 = 0;

in this example, this should be "var1 = 1;", so both legs are similar,
otherwise we end up with a dependency on the load.

Thanks,

Mathieu

>        return;
>    }
>    __smp_rmb();
>    var1 = 1;
> }
-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com