Date: Fri, 29 Jan 2010 10:21:14 -0800
From: Greg KH <gregkh@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cong Wang <amwang@redhat.com>,
       linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
       Miles Lane <miles.lane@gmail.com>,
       Heiko Carstens <heiko.carstens@de.ibm.com>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Larry Finger <Larry.Finger@lwfinger.net>, akpm@linux-foundation.org
Subject: Re: [Patch 0/2] sysfs: fix s_active lockdep warning
Message-ID: <20100129182114.GA13219@suse.de>
References: <20100129070516.4058.77227.sendpatchset@localhost.localdomain>
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 <4B629E7F.5020200@redhat.com>
 <m1zl3xt49k.fsf@fess.ebiederm.org>
 <20100129142223.GB12539@suse.de>
 <1264787848.24455.31.camel@laptop>
 <20100129181024.GA12934@suse.de>
 <1264788860.24455.35.camel@laptop>
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On Fri, Jan 29, 2010 at 07:14:20PM +0100, Peter Zijlstra wrote:
> On Fri, 2010-01-29 at 10:10 -0800, Greg KH wrote:
> > On Fri, Jan 29, 2010 at 06:57:28PM +0100, Peter Zijlstra wrote:
> > > On Fri, 2010-01-29 at 06:22 -0800, Greg KH wrote:
> > > > 
> > > > Heh, this whole mess is the very reason we didn't add lockdep support to
> > > > the driver core.  Nested devices that all look alike from the driver
> > > > core, are really different objects and the locking lifetimes are
> > > > separate, but lockdep can't see that. 
> > > 
> > > And here I through Alan Stern had a handle on making the driver core
> > > play nice.
> > 
> > It's not the driver core that is the issue here, it's that lockdep can't
> > handle the tree structure of devices that is represented in the kernel.
> > 
> > I don't think it is a driver core problem, but rather, a lockdep issue.
> 
> Right, we've been over that and I think I added enough lockdep
> annotations to make it work for the device tree. At least, Alan and I
> seemed to agree on that last time we talked about it.

Ah, I didn't realize that, very nice.

If so, then this sysfs lock stuff should be able to use those
annotations and we shouldn't have this issue, right?

thanks,

greg k-h
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