Re: Worst recursion in the kernel

From: David Hinds
Date: Wed Dec 03 2003 - 18:38:44 EST


On Wed, Dec 03, 2003 at 03:08:32PM -0800, Mike Fedyk wrote:
> On Wed, Dec 03, 2003 at 10:57:43PM +0000, Russell King wrote:
> > Yes, but the condition of the /data/ is such that it will not recurse.
> >
> > A pure "can this function call that function" analysis ignoring the
> > state of the data will say this will infinitely recuse. Include
> > the data, and you'll find it has a very definite recursion limit.
>
> Is the data verified?

Russell is using "data" loosely. Basically the logic goes like this:

read_cis_mem():
if sys_start is NULL then call validate_mem()

validate_mem():
set sys_start
call stuff that calls read_cis_mem()

so the functions do not require consistency of any external program
data to avoid recursion.

-- Dave

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