Problem with notifier_lock in notifier_chain_unregister with 2.4. 0-test5

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I am trying create a patch for the 3ware driver to have it notify the cards
firmware
of a pending shutdown using register_reboot_notifier() and
unregister_reboot_notifier().

The problem is that under SMP, the system gets partially hung in
notifier_chain_unregister()
in kernel/sys.c in this area:

int notifier_chain_unregister(struct notifier_block **nl, struct
notifier_block *n)
{
        write_lock (&notifier_lock); ----> The system gets stuck
right here and never gets this lock
        while ((*nl)!=NULL)
        {
                if ((*nl)==n)
                {
                        *nl=n->next;
                        write_unlock(&notifier_lock);
                        return 0;
                }
                nl=&(*nl)->next);
        }
        write_unlock(&notifier_lock);
        return -ENOENT;
}

It is probably worth noting that the 2.2.X kernels don't have this lock
scheme, and removing it fixes the
problem. Is this lock scheme correct in 2.4.0 ?

--
Adam Radford
Software Engineer
3ware, Inc.
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