linux-kernel - Re: [PATCH 3/3] ring-buffer: add design document

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.2.00.0906102324140.30552@gandalf.stny.rr.com>
Date:	Wed, 10 Jun 2009 23:25:46 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Theodore Tso <tytso@....edu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Mathieu Desnoyers <compudj@...stal.dyndns.org>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	"Martin J. Bligh" <mbligh@...igh.org>,
	Christoph Hellwig <hch@...radead.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Huang Ying <ying.huang@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Masami Hiramatsu <mhiramat@...hat.com>
Subject: Re: [PATCH 3/3] ring-buffer: add design document


On Thu, 11 Jun 2009, Hidetoshi Seto wrote:
> Steven Rostedt wrote:
> > +
> > +  +------+
> > +  |reader|          RING BUFFER
> > +  |page  |-------------------+
> > +  +------+ <---------------+ v
> > +    |  ^          +---+   +---+   +---+
> > +    |  |          |   |-->|   |-->|   |
> > +    |  |          |   |<--|   |<--|   |<-+
> > +    |  |          +---+   +---+   +---+  |
> > +    |  |             |             ^ |   |
> > +    |  |             +-------------+ |   |
> > +    |  +-----------------------------+   |
> > +    +------------------------------------+
> 
> It seems the middle of three pages have 2 prev arrows... ?

Yes that is a mistake. Thanks, I'll fix it.
> > +
> > +It does a cmpxchg with the pointer to the previous head page to make it
> > +point to the reader page. Note that the new pointer does not have the HEADER
> > +flag set.  This action atomically moves the head page forward.
> > +
> > +  +------+
> > +  |reader|          RING BUFFER
> > +  |page  |-------H-----------+
> > +  +------+ <---------------+ v
> > +    |  ^          +---+   +---+   +---+
> > +    |  |          |   |-->|   |-->|   |
> > +    |  |          |   |<--|   |<--|   |<-+
> > +    |  |          +---+   +---+   +---+  |
> > +    |  |             |             ^ |   |
> > +    |  |             +-------------+ |   |
> > +    |  +-----------------------------+   |
> > +    +------------------------------------+
> > +
> 
> Ditto.

Ditto too ;-)

Thanks,

-- Steve

--
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/