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    SubjectRe: [PATCH net-next-2.6] bnx2: remove cancel_work_sync() from remove_one
    Hello, David.

    On Mon, Dec 20, 2010 at 01:11:46PM -0800, David Miller wrote:
    > It would but we can't just make the change over to del_timer_sync()
    > otherwise we'd deadlock on netif_tx_lock().
    > But I think things might be OK as-is.
    > The timer is deleted by dev_deactivate_many() which resets the qdisc
    > to the no-op qdisc. Then it deletes the timer.
    > Any running timer will complete or see the no-op qdisc attached and
    > return immediately.
    > synchronize_rcu() is then executed which guarentees completion.
    > Since both the watchdog timer itself and the del_timer() call run
    > with netif_tx_lock() held, this makes sure the timer, once deleted,
    > will only see the no-op qdisc and return immediately if it is
    > amidst running, else it has already returned when the timer delete
    > completes.
    > So we might be OK here.

    Yeah, I agree the synchronize_rcu() there would guarantee the actual
    timer completion but as it currently stands it looks a bit too subtle.
    Maybe it's a good idea to add a big fat comment explaining that the
    the timer is guaranteed to stop after close() and how it's guaranteed
    through synchronize_rcu() at the moment? Also, it might be better to
    use synchronize_sched() there as timer synchronization through
    synchronize_rcu() is more of a happy accident.



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