Re: [PATCH] autofs4 - fix get_next_positive_subdir()

From: Ian Kent
Date: Wed May 23 2012 - 03:30:48 EST


On Wed, 2012-05-23 at 15:22 +0800, Ian Kent wrote:
> On Tue, 2012-05-22 at 19:53 -0700, Linus Torvalds wrote:
> > On Tue, May 22, 2012 at 7:49 PM, Ian Kent <ikent@xxxxxxxxxx> wrote:
> > >
> > > The locking for the list traversal in get_next_positive_subdir() is
> > > wrong, so fix it.
> >
> > As an explanation, this kind of thing is totally useless. It doesn't
> > actually give any information at all. It's like saying "change
> > locking"
> >
> > What happened, and why? Why is the new nested spinlock ok and won't
> > deadlock against other nested users? Wazzup?
>
> It's good that you questioned this Linus.
>
> Looking again at dput() I think the traversal still isn't quite right.
>
> For a start the test for d_count 0 or positive and hashed can never be

Correction, that second check is actually !(positive and hashed) in the
code.

> true since the point of the change was to take the d_lock of the
> d_subdirs dentry for the traversal.
>
> I'll need to work on this some more, thanks.
> Ian


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