Messages in this thread Patch in this message | | | Date | Wed, 19 Feb 2020 00:50:07 +0100 | From | Carmine Scarpitta <> | Subject | Re: [net-next 1/2] Perform IPv4 FIB lookup in a predefined FIB table |
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Hi David, Thanks for the review and sorry for the late reply
Indeed both call fib_table_lookup and rt_dst_alloc are exported for modules. However, several functions defined in route.c are not exported: - the two functions rt_cache_valid and rt_cache_route required to handle the routing cache - find_exception, required to support fib exceptions. This would require duplicating a lot of the IPv4 routing code. The reason behind this change is really to reuse the IPv4 routing code instead of doing a duplication.
For the fi member of the struct fib_result, we will fix it by initializing before "if (!tbl_known)"
Thanks, Carmine
On Sat, 15 Feb 2020 11:06:43 -0700 David Ahern <dsahern@gmail.com> wrote:
> On 2/12/20 6:09 PM, Carmine Scarpitta wrote: > > In IPv4, the routing subsystem is invoked by calling ip_route_input_rcu() > > which performs the recognition logic and calls ip_route_input_slow(). > > > > ip_route_input_slow() initialises both "fi" and "table" members > > of the fib_result structure to null before calling fib_lookup(). > > > > fib_lookup() performs fib lookup in the routing table configured > > by the policy routing rules. > > > > In this patch, we allow invoking the ip4 routing subsystem > > with known routing table. This is useful for use-cases implementing > > a separate routing table per tenant. > > > > The patch introduces a new flag named "tbl_known" to the definition of > > ip_route_input_rcu() and ip_route_input_slow(). > > > > When the flag is set, ip_route_input_slow() will call fib_table_lookup() > > using the defined table instead of using fib_lookup(). > > I do not like this change. If you want a specific table lookup, then why > just call fib_table_lookup directly? Both it and rt_dst_alloc are > exported for modules. Your next patch already does a fib table lookup. > > > > > > Signed-off-by: Carmine Scarpitta <carmine.scarpitta@uniroma2.it> > > Acked-by: Ahmed Abdelsalam <ahmed.abdelsalam@gssi.it> > > Acked-by: Andrea Mayer <andrea.mayer@uniroma2.it> > > Acked-by: Paolo Lungaroni <paolo.lungaroni@cnit.it> > > --- > > include/net/route.h | 2 +- > > net/ipv4/route.c | 22 ++++++++++++++-------- > > 2 files changed, 15 insertions(+), 9 deletions(-) > > > > diff --git a/include/net/route.h b/include/net/route.h > > index a9c60fc68e36..4ff977bd7029 100644 > > --- a/include/net/route.h > > +++ b/include/net/route.h > > @@ -183,7 +183,7 @@ int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src, > > u8 tos, struct net_device *devin); > > int ip_route_input_rcu(struct sk_buff *skb, __be32 dst, __be32 src, > > u8 tos, struct net_device *devin, > > - struct fib_result *res); > > + struct fib_result *res, bool tbl_known); > > > > int ip_route_use_hint(struct sk_buff *skb, __be32 dst, __be32 src, > > u8 tos, struct net_device *devin, > > diff --git a/net/ipv4/route.c b/net/ipv4/route.c > > index d5c57b3f77d5..39cec9883d6f 100644 > > --- a/net/ipv4/route.c > > +++ b/net/ipv4/route.c > > @@ -2077,7 +2077,7 @@ int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr, > > > > static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr, > > u8 tos, struct net_device *dev, > > - struct fib_result *res) > > + struct fib_result *res, bool tbl_known) > > { > > struct in_device *in_dev = __in_dev_get_rcu(dev); > > struct flow_keys *flkeys = NULL, _flkeys; > > @@ -2109,8 +2109,6 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr, > > if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr)) > > goto martian_source; > > > > - res->fi = NULL; > > - res->table = NULL; > > if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0)) > > goto brd_input; > > I believe this also introduces a potential bug. You remove the fi > initialization yet do not cover the goto case. > >
-- Carmine Scarpitta <carmine.scarpitta@uniroma2.it>
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