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    SubjectRe: [PATCH] kill empty chardev open/release methods
    > > If they literaly are 'return 0' you can just remove them, as a
    > > non-existing open op will just be fine.
    >
    > And here's a patch to do just that: remove all empty chardev
    > open/release methods. Based on the list compiled by Jonathan.

    Actually it turns out you can introduce bugs doing this when the BKL is
    pushed down.

    The problem is the methods are not NULL, they (with the lock pushed down
    are)

    {
    lock_kernel();
    unlock_kernel();
    }

    And we have drivers with setup code that does things in the wrong order
    but under the BKL. eg one I just fixed did

    misc_register()
    init locks
    allocate memory
    do stuff
    return 0;

    The lock/unlock in the open happens to save your butt against the wrong
    order of intialisation because the open cannot occur before the lock is
    taken, and thanks to the BKL it cannot make any progress until the setup
    is completed. Fun too - udev loves opening things as they appear so in
    some cases we might actually trigger them too.

    So when you remove the _open() empty methods *please* make sure you have
    verified the correctness and ordering of the entire registration path.
    I've found three examples of this so far just cleaning up
    drivers/watchdog.

    Alan


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