Re: [PATCH] namespace.c: fix race in mark_mounts_for_expiry()

[Miklos Szeredi <miklos@szeredi.hu>]

> > This patch fixes a race found by Ram in mark_mounts_for_expiry() in
> > The solution is to make the atomic_read() and the get_namespace() into
> > a single atomic operation.  The patch does this in a fairly ugly way
> > (see comment above fix), which should be safe regardless.
> 
> That it certainly is.  What's more, there is a trivial way to deal with
> that crap - have put_namespace() do atomic_dec_and_lock() instead of
> atomic_dec_and_test().  And use the same spinlock (vfsmount_lock would be
> an obvious choice) to protect the atomicity here.  End of story.

Right.

Question is, why did nobody think of that before :)

Thanks,
Miklos
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