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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Thu, 16 Aug 2007 11:20:53 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Segher Boessenkool <segher@...nel.crashing.org>
CC:	paulmck@...ux.vnet.ibm.com, heiko.carstens@...ibm.com,
	horms@...ge.net.au, linux-kernel@...r.kernel.org,
	rpjday@...dspring.com, ak@...e.de, netdev@...r.kernel.org,
	cfriesen@...tel.com, akpm@...ux-foundation.org,
	torvalds@...ux-foundation.org, linux-arch@...r.kernel.org,
	jesper.juhl@...il.com, zlynx@....org, schwidefsky@...ibm.com,
	Chris Snook <csnook@...hat.com>, davem@...emloft.net,
	wensong@...ux-vs.org, wjiang@...ilience.com,
	David Howells <dhowells@...hat.com>
Subject: Re: [PATCH 6/24] make atomic_read() behave consistently on frv

Segher Boessenkool wrote:
>> Please check the definition of "cache coherence".
> 
> 
> Which of the twelve thousand such definitions?  :-)

Every definition I have seen says that writes to a single memory
location have a serial order as seen by all CPUs, and that a read
will return the most recent write in the sequence (with a bit of
extra mumbo jumbo to cover store queues and store forwarding).

Within such a definition, I don't see how would be allowed for a
single CPU to execute reads out of order and have the second read
return an earlier write than the first read.

-- 
SUSE Labs, Novell Inc.
-
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