Re: [PATCH 1/4] lockdep: lock_set_subclass() fix

From: Borislav Petkov
Date: Mon Nov 07 2011 - 08:54:57 EST


On Mon, Nov 07, 2011 at 01:34:39PM +0100, Peter Zijlstra wrote:
> On Fri, 2011-11-04 at 17:26 +0800, Yong Zhang wrote:
> > Since commit f59de89 [lockdep: Clear whole lockdep_map on initialization],
> > lockdep_init_map() will clear all the struct. But it will break
> > lock_set_class()/lock_set_subclass(). A typical race condition
> > is like below:
>
> This is a horridly ugly patch, why not simply revert that memset commit?
> I really can't see the point of that, and keeping the name/key pointers
> around (which can only be over-written with the same values, right?)
> would also cure the problem.

FWIW,

I ran the box with the memset commit reverted for a couple of days
before applying Young's patches and it didn't show any signs of
problems.

--
Regards/Gruss,
Boris.
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