From: Peter Zijlstra <peterz@infradead.org>
To: David Brownell <david-b@pacbell.net>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Dave Young <hidave.darkstar@gmail.com>, Greg KH <gregkh@suse.de>,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [PATCH 01/12] Use mutex instead of semaphore in driver core
Date: Sun, 30 Dec 2007 13:13:51 +0100 [thread overview]
Message-ID: <1199016831.31975.7.camel@lappy> (raw)
In-Reply-To: <200712292242.47960.david-b@pacbell.net>
On Sat, 2007-12-29 at 22:42 -0800, David Brownell wrote:
> On Saturday 29 December 2007, Alan Stern wrote:
> > There's no way to remove these, which means there's
> > no way to prevent lockdep from issuing a warning.
>
> There may be no *efficient* way to do that. If it tracked
> every lock individually these false alarms could go away;
> but that would increase the overhead to create and destroy
> such locks too.
No, tracking locks individually defeats the power of lockdep, that is
warning of lock inversion before it actually happens. That really
requires classes.
Annotating a tree requires grouping per level, and that isn't
particularly hard (although I haven't yet tried it for the device tree -
doing this conversion is still on my todo list). The hardest part of the
device->sem conversion is the suspend/resume part, where it locks the
whole tree and lockdep is limited in tracking held locks.
next prev parent reply other threads:[~2007-12-30 12:14 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-29 1:01 [PATCH 01/12] Use mutex instead of semaphore in driver core Dave Young
2007-12-29 1:29 ` Peter Zijlstra
2007-12-29 1:36 ` Dave Young
2007-12-29 1:40 ` Dave Young
2007-12-29 1:42 ` Peter Zijlstra
2007-12-29 1:52 ` Dave Young
2007-12-29 1:57 ` Peter Zijlstra
2007-12-29 2:03 ` Dave Young
2007-12-29 2:36 ` Dave Young
2007-12-29 4:42 ` Greg KH
2007-12-29 5:06 ` Dave Young
2007-12-29 7:07 ` Dave Young
2007-12-29 17:07 ` Greg KH
2008-01-02 0:54 ` Dave Young
2008-01-02 5:18 ` Greg KH
2008-01-02 5:25 ` David Miller
2008-01-02 7:00 ` Greg KH
2008-01-02 7:52 ` David Miller
2008-01-02 12:39 ` Jarek Poplawski
2008-01-02 13:12 ` Jarek Poplawski
2008-01-02 16:08 ` Alan Stern
2008-01-03 1:00 ` Dave Young
2008-01-02 5:37 ` Dave Young
2007-12-29 22:01 ` Alan Stern
2007-12-30 6:42 ` David Brownell
2007-12-30 12:13 ` Peter Zijlstra [this message]
2008-01-08 16:54 ` Jiri Kosina
2008-01-02 0:58 ` Dave Young
2008-01-02 16:06 ` Alan Stern
2008-01-05 9:30 ` Andrew Morton
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