[PATCH RFC] ct: endless loop when initializing netfilter/ct cache

[Holger Eitzenberger]

Hi Thomas,

> > Yes, the insert is O(n^2) since introducing dup check.  With
> > thousands of conntracks it is currently unusable.
> > 
> > If you want I can cook an RFC path for that.
> 
> That sounds great. Thanks!

The cache flags are currently set from cache_ops, it would be a compile
time decision whether to use caching or not or a subusystem.  So
it would eventually require to pass user-specified flags to
the cache creating functions.

But I think there is a smarter way.

The actual issue is in nl_cache_refill().  I noticed that it
explicitely clears the cache before, then doing the dump request.
So in this case it makes sense to just skip the dupe check in
nl_cache_pickup(), because the dump AFAIK guarantees uniqueness.

But there is another user of nl_cache_pickup() in flnl_lookup(), which
requires the dupe check.  So we just can't remove dupe check entirely.

I therefore have modified nl_cache_pickup() to have an additional 3rd
argument, which tells whether dupe_check is required or not.  Since
nl_cache_pickup is a non-static function this then is an API change.

Also note that last argument ideally would be C99 'bool', but
stdbool.h currently is not #included anywhere - and I therefore chose
'int' instead.  Should I change signature to use 'bool' instead?

Please check RFC patch.

 /Holger

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