Re: [PATCH] netfilter: use per-CPU recursive lock {XIV}

[Patrick McHardy]

Eric Dumazet wrote:
> Stephen Hemminger a écrit :
> > In days of old in 2.6.29, netfilter did locketh using a 
> > lock of the reader kind when doing its table business, and do
> > a writer when with pen in hand like a overworked accountant
> > did replace the tables. This sucketh and caused the single
> > lock to fly back and forth like a poor errant boy.
> >
> > But then netfilter was blessed with RCU and the performance
> > was divine, but alas there were those that suffered for
> > trying to replace their many rules one at a time.
> >
> > So now RCU must be vanquished from the scene, and better
> > chastity belts be placed upon this valuable asset most dear.
> > The locks that were but one are now replaced by one per suitor.
> >
> > The repair was made after much discussion involving
> > Eric the wise, and Linus the foul. With flowers springing
> > up amid the thorns some peace has finally prevailed and
> > all is soothed. This patch and purple prose was penned by
> > in honor of "Talk like Shakespeare" day.

Hehe.

> >  static int __init xt_init(void)
> >  {
> > -	int i, rv;
> > +	unsigned int i;
> > +	int rv;
> > +	static struct lock_class_key xt_lock_key[NR_CPUS];
>
> Could we avoid this [NR_CPUS] thing ?
>
> > +
> > +	for_each_possible_cpu(i) {
> > +		rwlock_t *lock = &per_cpu(xt_info_locks, i);
> > +
> > +		rwlock_init(lock);
> > +		lockdep_set_class(lock, xt_lock_key+i);
> > +	}
>
>
> Did you tried :
>
> static DECLARE_PER_CPU(struct lock_class_key, xt_locks_key);

Either way is fine with me, I'll wait for Stephen to state his opinion.
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