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

[Al Viro]

On Fri, May 20, 2005 at 10:41:24AM +0200, Miklos Szeredi wrote:
> 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.
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