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    SubjectRe: [PATCH 3/3] IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
    On Tuesday 03 October 2006 11:03 am, Alan Stern wrote:

    > > > Notice another questionable use of hcd->state.
    > >
    > > Questionable in what way? When that code is called to clean up
    > > after driver death, that loop must be ignored ... every pending I/O
    > > can safely be scrubbed. That's the main point of that particular
    > > HC_IS_RUNNING() test. In other cases, it's essential not to touch
    > > DMA queue entries that the host controller is still using.
    > Questionable because changes to hcd->state aren't synchronized with the
    > driver. In this case it probably doesn't end up making any difference.

    The driver changes hcd->state with its spinlock held ... or it did,
    last time I audited that code.

    > Removing "regs &&" might change other aspects too. For instance, does
    > this routine ever get called from a timer routine, where regs would
    > normally be NULL? In such situations removing "regs &&" would reverse
    > the sense of the test.

    As I said in my previous comments: should not be an issue. OHCI doesn't
    have timers. That routine is normally called in_irq(), with the other
    two call sites being cases where the controller is stopped.

    - Dave
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