netdev - Re: [PATCH net v5 3/6] ipv4: Dump route exceptions if requested

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Message-ID: <20190620015715.7f243380@redhat.com>
Date:   Thu, 20 Jun 2019 01:57:15 +0200
From:   Stefano Brivio <sbrivio@...hat.com>
To:     David Ahern <dsahern@...il.com>
Cc:     David Miller <davem@...emloft.net>, Jianlin Shi <jishi@...hat.com>,
        Wei Wang <weiwan@...gle.com>, Martin KaFai Lau <kafai@...com>,
        Eric Dumazet <edumazet@...gle.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        netdev@...r.kernel.org
Subject: Re: [PATCH net v5 3/6] ipv4: Dump route exceptions if requested

On Tue, 18 Jun 2019 08:48:23 -0600
David Ahern <dsahern@...il.com> wrote:

> > +++ b/net/ipv4/fib_trie.c
> > @@ -2000,28 +2000,92 @@ void fib_free_table(struct fib_table *tb)
> >  	call_rcu(&tb->rcu, __trie_free_rcu);
> >  }
> >  
> > +static int fib_dump_fnhe_from_leaf(struct fib_alias *fa, struct sk_buff *skb,
> > +				   struct netlink_callback *cb,
> > +				   int *fa_index, int fa_start)
> > +{
> > +	struct net *net = sock_net(cb->skb->sk);
> > +	struct fib_info *fi = fa->fa_info;
> > +	struct fnhe_hash_bucket *bucket;
> > +	struct fib_nh_common *nhc;
> > +	int i, genid;
> > +
> > +	if (!fi || fi->fib_flags & RTNH_F_DEAD)
> > +		return 0;
> > +
> > +	nhc = fib_info_nhc(fi, 0);  
> 
> This should be a loop over fi->fib_nhs for net:
> 	for (i = 0; i < fi->fib_nhs; i++) {
> 		nhc = fib_info_nhc(fi, 0);
> 		...
> 
> and a loop over fib_info_num_path(fi) for net-next:
> 	for (i = 0; i < fib_info_num_path(fi); i++) {
> 		nhc = fib_info_nhc(fi, 0);
> 		...

Right, I started this from net-next and only later "adapted" to net
clearly in the wrong way. Thanks for providing both expressions. Fixed
in v6.

> 
> > +	if (nhc->nhc_flags & RTNH_F_DEAD)
> > +		return 0;  
> 
> And then the loop over the exception bucket could be a helper in route.c
> in which case you don't need to export rt_fill_info and nhc_exceptions
> code does not spread to fib_trie.c

Cleaner I guess, changed in v6.
 
> > +
> > +	bucket = rcu_dereference(nhc->nhc_exceptions);
> > +	if (!bucket)
> > +		return 0;
> > +
> > +	genid = fnhe_genid(net);
> > +
> > +	for (i = 0; i < FNHE_HASH_SIZE; i++) {
> > +		struct fib_nh_exception *fnhe;
> > +
> > +		for (fnhe = rcu_dereference(bucket[i].chain); fnhe;
> > +		     fnhe = rcu_dereference(fnhe->fnhe_next)) {
> > +			struct flowi4 fl4 = {};  
> 
> rather than pass an empty flow struct, update rt_fill_info to handle a
> NULL fl4; it's only a few checks.

Added patch and changed in v6.

-- 
Stefano