linux-kernel - Re: [RFC PATCH] printk: Use ACCESS_ONCE() instead of a volatile type

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]

Date:	Thu, 13 Nov 2014 19:41:00 -0800
From:	Joe Perches <joe@...ches.com>
To:	Pranith Kumar <bobby.prani@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Petr Mladek <pmladek@...e.cz>, Jan Kara <jack@...e.cz>,
	"Luis R. Rodriguez" <mcgrof@...e.com>,
	Alex Elder <elder@...aro.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	open list <linux-kernel@...r.kernel.org>,
	paulmck@...ux.vnet.ibm.com
Subject: Re: [RFC PATCH] printk: Use ACCESS_ONCE() instead of a volatile type

On Thu, 2014-11-13 at 22:21 -0500, Pranith Kumar wrote:
> Remove volatile type qualifier and use ACCESS_ONCE() in its place for each
> access. Using volatile is not recommended as documented in
> Documentation/volatile-considered-harmful.txt.
> 
> Here logbuf_cpu is a local variable and it is not clear how it is being accessed
> concurrently. We should remove volatile accesses entirely here, but for now make
> a safer change of using ACCESS_ONCE().

Not recommended does not mean "don't ever use".

Forcing the volatile at each use site instead
of the declaration isn't necessarily better.

I think the code is more readable as-is but I'm
not going to object if Andrew picks this up...


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/