Re: Worst recursion in the kernel

From: Russell King
Date: Wed Dec 03 2003 - 17:58:49 EST

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 -
maintainer of: 2.6 PCMCIA -
2.6 Serial core
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