Re: idr_get_new_exact ?

[Steve Wise]

On 09/20/2010 02:31 PM, Andrew Morton wrote:
> On Mon, 20 Sep 2010 16:11:31 +0200
> Ohad Ben-Cohen<ohad@xxxxxxxxxx>  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 :)).

Steve.

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