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    SubjectRe: [PATCH 5/8] staging: vme: add functions for bridge module refcounting
    On Fri, Aug 05, 2011 at 10:24:55 +0100, Martyn Welch wrote:
    > I think that by refcounting the resources being used we
    > will know whether a bridge module is being used or not,
    > thus whether it can be unloaded or not.

    But the granularity is wrong; if you want to know whether the
    bridge is being used, just keep track of the devices *which
    want to make known* that they're under the bridge.

    > By reference counting the use of resources we minimise the
    > chance of poorly written drivers using resources, but not
    > registering the fact that they are in fact using a VME bridge.

    A driver leaking a resource will then leave a bogus refcount
    on the bus driver--a clear case of self-inflicted pain.

    The argument of "poorly written drivers" does not apply;
    I would expect all the merged drivers to be "good quality"
    only, that's why we want to be upstream and why we put effort
    in reviewing. Your point is well-intentioned, but in
    practice we'd be shooting ourselves in the foot, potentially
    ending up with an unremovable vme bridge module--which is
    worse than a driver leaking a resource.

    Refcounting must be kept simple & stupid; doing it behind the
    backs of the drivers we're trying to protect is a mistake.


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