linux-kernel - Re: [PATCH] lglock: make lg_lock_global() actually lock globally

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: <20100827055105.GA3857@amd>
Date:	Fri, 27 Aug 2010 15:51:05 +1000
From:	Nick Piggin <npiggin@...nel.dk>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Nick Piggin <npiggin@...nel.dk>, Tejun Heo <tj@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jonathan Corbet <corbet@....net>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Al Viro <viro@...iv.linux.org.uk>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] lglock: make lg_lock_global() actually lock globally

On Thu, Aug 26, 2010 at 01:45:39PM +0200, Peter Zijlstra wrote:
> On Thu, 2010-08-26 at 21:38 +1000, Nick Piggin wrote:
> > I think for CPU plug, stop_machine is reasonable (especially
> > considering it is required in unload, which means any frequent
> > amount of cpu plug activity already will require stop_machine to
> > run anyway). 
> 
> How is it required? 

Well, as is implemented.

 
> Its currently implemented as such, and its sure a lot easier to do that
> way, but I could imagine that unplugging a CPU could be done without it.
 
I would much prefer the rules to be simpler and easier for all
other kernel code, and keep complexity and overheads in cpu
plug/unplug.

I don't see what is so nice about stop_machine()less cpu plug/unplug
or module unload. Module load definitely is nice because you can
have a lot of modules and on demand loading from non-privileged
operations.

--
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/