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    SubjectRe: idr_get_new_exact ?
    On 09/20/2010 02:31 PM, Andrew Morton wrote:
    > On Mon, 20 Sep 2010 16:11:31 +0200
    > Ohad Ben-Cohen<> wrote:
    >> Occasionally, drivers care about the value that idr associates with
    >> their pointers.
    >> Today we have idr_get_new_above() which allocates a new idr entry
    >> above or equal to a given starting id, but sometimes drivers need to
    >> force an exact value.
    >> To overcome this small API gap, drivers are wrapping idr_get_new_above
    >> and then either BUG_ON() or just call idr_remove() and returns -EBUSY
    >> when idr allocates them an id which is different than their requested
    >> value.
    >> There are only a handful of users who need this (see below. especially
    >> note the i2c comment :), but it might be nice to have such an API (a
    >> bit less of code, and a bit less error prone).
    >> Would something like the below be desirable/acceptable ?
    > It seems OK to me - it's an improvement over what we have now.

    Looks ok to me also. This is exactly what cxgb* needs. IE the driver
    manages the ID space and never expects an idr insertion to fail because
    its already inserted. That constitutes a driver bug (which is why the
    BUG_ON() is there :)).


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