linux-kernel - Re: [PATCH 1/5] atomics: add acquire/release/relaxed variants of some atomic 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] [day] [month] [year] [list]

Message-ID: <20150714155500.GQ16213@arm.com>
Date:	Tue, 14 Jul 2015 16:55:06 +0100
From:	Will Deacon <will.deacon@....com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"Waiman.Long@...com" <Waiman.Long@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH 1/5] atomics: add acquire/release/relaxed variants of
 some atomic operations

On Tue, Jul 14, 2015 at 12:38:01PM +0100, Peter Zijlstra wrote:
> On Tue, Jul 14, 2015 at 12:31:47PM +0100, Will Deacon wrote:
> > #ifndef atomic_add
> > #define atomic_add(args...)	(void)atomic_add_return_relaxed(args);
> > 
> > It would mean a new architecture only has to define a barrier instruction
> > and a handful of relaxed atomics for a bare-minimum atomic.h avoiding
> > spinlocks.
> 
> Look at include/asm-generic/atomic.h, all you need is a cmpxchg().
> 
> We could easily change that to be cmpxchg_relaxed() and a few barriers.

Ok, I'll leave that part for now and implement your original suggestion
as a starting point.

Will
--
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/