[ofa-general] Re: idr_get_new_above() limitation?
Jim Houston
jim.houston at ccur.com
Mon Jul 2 17:31:40 PDT 2007
On Mon, 2007-07-02 at 19:19 +0200, Hoang-Nam Nguyen wrote:
> i=3fffffff token=3fffffff t=000000003fffffff
> i=40000000 token=40000000 t=0000000000000000
> Invalid object 0000000000000000. Expected 40000000
>
> That means token 0x40000000 seems to be the "upper boundary" of idr_find().
> However the behaviour is not consistent in that it was returned by
> idr_get_new_above().
Hi Nam,
Yes this is a bug. Thanks for the great test module.
The problem is in idr_get_new_above_int() in the loop which
adds new layers to the top of the radix tree. It is failing
the "layers < (MAX_LEVEL - 1)" test. It doesn't allocate the
new layer but still calls sub_alloc() which relies on having
the new layer properly constructed. I believe that it is
allocating the slot which corresponds to id = 0.
I believe this is an off by one error in calculating the
MAX_LEVEL value. I will do a more careful review and post
a fix in the next day or so. I have been in Ottawa for OLS.
I'm flying home tomorrow.
Jim Houston - Concurrent Computer Corp.
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