Re: Worst recursion in the kernel

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Wed, Dec 03, 2003 at 08:04:40PM +0100, Jörn Engel wrote:
> You are right, verify_cis_cache() does not belong into the list.
> Gotta see where that bug comes from.  set_cis_map() is correct,
> though.  It does call validate_mem(), at least in my copy of
> 2.6.0-test11:
> 
> static unsigned char *
> set_cis_map(struct pcmcia_socket *s, unsigned int card_offset, unsigned int flags)
> {
>     pccard_mem_map *mem = &s->cis_mem;
>     if (!(s->features & SS_CAP_STATIC_MAP) &&
> 	mem->sys_start == 0) {
> 	validate_mem(s);
> 	...
> 
> You can have the current code if you are really interested.  It takes
> the call graph as generated by smatch and follows all function calls.
> If it ever revisits a function that was already on the path, it prints
> out a warning like above.

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.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core