Re: [PATCH 1/3][-mm] add class_reclassify macro
From: Dave Young
Date: Tue May 20 2008 - 22:06:00 EST
On Wed, May 21, 2008 at 3:23 AM, Andrew Morton
> On Tue, 20 May 2008 11:36:41 -0600
> Matthew Wilcox <matthew@xxxxxx> wrote:
>> On Tue, May 20, 2008 at 10:30:45AM -0700, Andrew Morton wrote:
>> > Well what are these lockdep warnings? Normally such a warning means that
>> > we have a locking bug. I _assume_ that you've determined that the warnings
>> > are false-positives?
>> Andrew, we already discussed this on the thread you started that you
>> then ignored ...
> All pertinent information should be in a patch's changelog. Then this
> sort of confusion will not occur.
My wrong. should do this in advance.
>> > The warning which Mariusz Kozlowski discovered ("Subject: Re:
>> > 2.6.26-rc2-mm1: possible circular locking dependency detected") was
>> > triggered by the "class semaphore to mutex" conversion and it looks
>> > like a real bug to me. Would your patch prevent warnings such as that
>> > one from being available to us?
>> The problem is that you add one type of class which then adds devices
>> that are of another class. This is not a bug. My proposal is to give
>> each sysfs class its own lock class; Dave's is to only do it for the
>> two classes he knows about that do this.
> Well that sounds reasonable. I'm not sure that we should introduce
> generic-looking helper infrastructure to do it, however.
> Anyway I'll happily sit back and let you guys and Greg sort this one out ;)
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