From: Andrew Morton <akpm@linux-foundation.org>
To: paulmck@kernel.org
Cc: David Laight <David.Laight@ACULAB.COM>,
"'Marco Elver'" <elver@google.com>,
Chris Wilson <chris@chris-wilson.co.uk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"intel-gfx@lists.freedesktop.org"
<intel-gfx@lists.freedesktop.org>,
Randy Dunlap <rdunlap@infradead.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] list: Prevent compiler reloads inside 'safe' list iteration
Date: Wed, 11 Mar 2020 19:58:10 -0700 [thread overview]
Message-ID: <20200311195810.959d4f40d6013ee59a238cf3@linux-foundation.org> (raw)
In-Reply-To: <20200310154749.GZ2935@paulmck-ThinkPad-P72>
On Tue, 10 Mar 2020 08:47:49 -0700 "Paul E. McKenney" <paulmck@kernel.org> wrote:
> On Tue, Mar 10, 2020 at 03:05:57PM +0000, David Laight wrote:
> > From: Marco Elver
> > > Sent: 10 March 2020 14:10
> > ...
> > > FWIW, for writes we're already being quite generous, in that plain
> > > aligned writes up to word-size are assumed to be "atomic" with the
> > > default (conservative) config, i.e. marking such writes is optional.
> > > Although, that's a generous assumption that is not always guaranteed
> > > to hold (https://lore.kernel.org/lkml/20190821103200.kpufwtviqhpbuv2n@willie-the-truck/).
> >
> > Remind me to start writing everything in assembler.
>
> Been there, done that. :-/
>
> > That and to mark all structure members 'volatile'.
>
> Indeed. READ_ONCE() and WRITE_ONCE() get this same effect, but without
> pessimizing non-concurrent accesses to those same members. Plus KCSAN
> knows about READ_ONCE(), WRITE_ONCE(), and also volatile members.
>
So I take it from all the above that we should do this.
Did anyone actually review the code? :)
prev parent reply other threads:[~2020-03-12 2:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 9:21 Chris Wilson
2020-03-10 11:36 ` David Laight
2020-03-10 11:50 ` Chris Wilson
2020-03-10 12:23 ` David Laight
2020-03-10 12:50 ` Chris Wilson
2020-03-10 12:50 ` Paul E. McKenney
2020-03-10 13:52 ` Mark Rutland
2020-03-10 14:09 ` Marco Elver
2020-03-10 15:05 ` David Laight
2020-03-10 15:47 ` Paul E. McKenney
2020-03-12 2:58 ` Andrew Morton [this message]
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