lkml.org 
[lkml]   [2007]   [Jul]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: idr_get_new_above() limitation?
From
Date
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.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-07-03 02:47    [W:0.102 / U:0.248 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site