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SubjectRe: [PATCH 09/62] atm/nicstar: convert to idr_alloc()
On Mon, 4 Feb 2013 09:06:24 -0800
Tejun Heo <tj@kernel.org> wrote:

> Hello, Chas.
>
> On Mon, Feb 04, 2013 at 09:04:10AM -0500, chas williams - CONTRACTOR wrote:
> > I don't quite understand your comment. idr_pre_get() returns 0 in the
> > case of failure.
>
> So, if you do the following,
>
> int id1 = 0, id2 = 0;
>
> if (!id1)
> err = idr_get_new_above(&card->idr, handle1, 0, &id1);
> if (!id2 && err == 0)
> err = idr_get_new_above(&card->idr, handle2, 0, &id2);
> if (err)
> goto out;
>
> You have no way of telling whether id1/2 are allocated or not. 0 is
> the special "not allocated" value but it also is a valid ID. The
> error path should be freeing id1/2 if either of them has been
> allocated but it doesn't and can't with 0 as the non-allocated value.

yeah, i see now. it didn't understand what idr_get_new_above() was
doing with the start id. i assumed that it would return something
greater than the start id. i guess it never did return the starting id
(atleast after some initial failure).

additionally, yes, cleaning up if the second allocation failed was never
done.


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