netdev - Re: [PATCH 6/24] make atomic_read() behave consistently on frv

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 10 Aug 2007 21:29:43 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Chris Snook <csnook@...hat.com>, dhowells@...hat.com,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
	torvalds@...ux-foundation.org, netdev@...r.kernel.org,
	akpm@...ux-foundation.org, ak@...e.de, heiko.carstens@...ibm.com,
	davem@...emloft.net, schwidefsky@...ibm.com, wensong@...ux-vs.org,
	horms@...ge.net.au, wjiang@...ilience.com, cfriesen@...tel.com,
	zlynx@....org, rpjday@...dspring.com, jesper.juhl@...il.com
Subject: Re: [PATCH 6/24] make atomic_read() behave consistently on frv

On Sat, Aug 11, 2007 at 08:54:46AM +0800, Herbert Xu wrote:
> Chris Snook <csnook@...hat.com> wrote:
> > 
> > cpu_relax() contains a barrier, so it should do the right thing.  For 
> > non-smp architectures, I'm concerned about interacting with interrupt 
> > handlers.  Some drivers do use atomic_* operations.
> 
> What problems with interrupt handlers? Access to int/long must
> be atomic or we're in big trouble anyway.

Reordering due to compiler optimizations.  CPU reordering does not
affect interactions with interrupt handlers on a given CPU, but
reordering due to compiler code-movement optimization does.  Since
volatile can in some cases suppress code-movement optimizations,
it can affect interactions with interrupt handlers.

						Thanx, Paul
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html