netdev - Re: [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver

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Date:	Wed, 20 Feb 2008 22:37:57 +0000
From:	James Chapman <jchapman@...alix.com>
To:	Jarek Poplawski <jarkao2@...il.com>
CC:	David Miller <davem@...emloft.net>,
	Paul Mackerras <paulus@...ba.org>, netdev@...r.kernel.org
Subject: Re: [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver

Jarek Poplawski wrote:

>>> (testing patch #1)
> 
> But I hope you tested with the fixed (take 2) version of this patch...

Yes I did. :)

But I just got another lockdep error (attached).

> Since it's quite experimental (testing) this patch could be wrong
> as it is, but I hope it should show the proper way to solve this
> problem. Probably you did some of these, but here are a few of my
> suggestions for testing this:
> 
> 1) try my patch with your full bh locking changing patch;
> 2) add while loops to these trylocks on failure, with e.g.  __delay(1);
>    this should work like full locks again, but there should be no (this
>    kind of) lockdep reports;

Hmm, isn't this just bypassing the lockdep checks?

> 3) I send here another testing patch with this second way to do this:
>    on the write side, but it's even more "experimental" and only a
>    proof of concept (should be applied on vanilla ppp_generic).

I'll look over it. I think I need to take a step back and look at what's 
happening in more detail though.

-- 
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development


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