netdev - Re: rib_trie / Fix inflate_threshold

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Date:	Fri, 26 Jun 2009 22:37:13 +0200
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Robert Olsson <robert@...ur.slu.se>
Cc:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Robert Olsson <Robert.Olsson@...a.slu.se>,
	Eric Dumazet <dada1@...mosbay.com>,
	=?ISO-8859-2?Q?Pawe=B3_Staszewski?= 
	<pstaszewski@...are.pl>, Robert Olsson <robert.olsson@....uu.se>,
	Linux Network Development list <netdev@...r.kernel.org>
Subject: Re: rib_trie / Fix inflate_threshold_root. Now=15 size=11 bits

On Fri, Jun 26, 2009 at 10:26:53PM +0200, Robert Olsson wrote:
> 
> 
> Yes looks like a good solution but maybe it safest to synchronize unconditionally?

Hmm... I lost around half an hour for this doubt... Sure! (Unless
there are some strange cases which very often create and destroy very
small tables?)

Thanks,
Jarek P.

> 
> 
> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> index 012cf5a..9cb8623 100644
> --- a/net/ipv4/fib_trie.c
> +++ b/net/ipv4/fib_trie.c
> @@ -1028,8 +1028,11 @@ static void trie_rebalance(struct trie *t, struct tnode *tn)
>  	}
>  
>  	/* Handle last (top) tnode */
> -	if (IS_TNODE(tn))
> +	if (IS_TNODE(tn)) {
> +		/* force memory freeing after last changes */
> +		synchronize_rcu();
>  		tn = (struct tnode *)resize(t, (struct tnode *)tn);
> +	}
>  
>  	rcu_assign_pointer(t->trie, (struct node *)tn);
>  	tnode_free_flush();
> 
> Cheers
> 						--ro
> 
> Jarek Poplawski writes:
> 
>  >  net/ipv4/fib_trie.c |    8 ++++++--
>  >  1 files changed, 6 insertions(+), 2 deletions(-)
>  > 
>  > diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
>  > index 012cf5a..98b31a1 100644
>  > --- a/net/ipv4/fib_trie.c
>  > +++ b/net/ipv4/fib_trie.c
>  > @@ -1008,7 +1008,7 @@ static void trie_rebalance(struct trie *t, struct tnode *tn)
>  >  {
>  >  	int wasfull;
>  >  	t_key cindex, key;
>  > -	struct tnode *tp;
>  > +	struct tnode *tp, *oldtnode = tn;
>  >  
>  >  	key = tn->key;
>  >  
>  > @@ -1028,8 +1028,12 @@ static void trie_rebalance(struct trie *t, struct tnode *tn)
>  >  	}
>  >  
>  >  	/* Handle last (top) tnode */
>  > -	if (IS_TNODE(tn))
>  > +	if (IS_TNODE(tn)) {
>  > +		/* force memory freeing after last changes */
>  > +		if (oldtnode != tn)
>  > +			synchronize_rcu();
>  >  		tn = (struct tnode *)resize(t, (struct tnode *)tn);
>  > +	}
>  >  
>  >  	rcu_assign_pointer(t->trie, (struct node *)tn);
>  >  	tnode_free_flush();
>  > --
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