netdev - Re: [PATCH 2/2] lockdep: check that no locks held at freeze time

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Message-ID: <20130506121106.GA25615@amd.pavel.ucw.cz>
Date:	Mon, 6 May 2013 14:11:06 +0200
From:	Pavel Machek <pavel@....cz>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Ingo Molnar <mingo@...nel.org>, Colin Cross <ccross@...roid.com>,
	Andrew Morton <akpm@...l.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Len Brown <len.brown@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Ingo Molnar <mingo@...hat.com>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	"David S. Miller" <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mandeep Singh Baines <msb@...omium.org>,
	Paul Walmsley <paul@...an.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Oleg Nesterov <oleg@...hat.com>, linux-nfs@...r.kernel.org,
	Linux PM list <linux-pm@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, Ben Chan <benchan@...omium.org>
Subject: Re: [PATCH 2/2] lockdep: check that no locks held at freeze time

1;2403;0cOn Mon 2013-05-06 10:55:47, Peter Zijlstra wrote:
> On Sun, May 05, 2013 at 11:18:44AM +0200, Ingo Molnar wrote:
> > That's the old 32-bit x86 trick to compute 'current' from the kernel stack 
> > pointer.
> > 
> > It can be done better - for example on platforms with optimized percpu 
> > variables (x86-64) it looks like this:
> 
> Doesn't i386 have all the funny per-cpu stuff too? So the only reason it still
> does the fugly stack based thing is because nobody could be arsed to do the
> work of converting it.

(Note that the quoted example was from ARM. But also note that the
percpu stuff requires memory access, so...)
									Pavel
-- 
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