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Re: [dm-devel] 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<ohad wizery com>  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

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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