linux-kernel - Re: [PATCH RFC] percpu: add data dependency barrier in percpu accessors and operations

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: <alpine.DEB.2.11.1407150903570.10593@gentwo.org>
Date:	Tue, 15 Jul 2014 09:06:00 -0500 (CDT)
From:	Christoph Lameter <cl@...two.org>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
cc:	Rusty Russell <rusty@...tcorp.com.au>, Tejun Heo <tj@...nel.org>,
	David Howells <dhowells@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] percpu: add data dependency barrier in percpu
 accessors and operations

On Tue, 15 Jul 2014, Paul E. McKenney wrote:

> If I understand your initialization procedure correctly, you need at least
> an smp_wmb() on the update side and at least an smp_read_barrier_depends()
> on the read side.

A barrier for data that is not in the cache of the read side? That has
not been accessed yet (well there could have been a free_percpu before but
if so then the cache line was evicted by the initialization code).


--
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/