netdev - Re: [PATCH net-next 2/3] ipv6: start fib6 gc on RTF

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Message-ID: <20171017215352.bdwlrp7htglkwr3v@kafai-mbp.dhcp.thefacebook.com>
Date:   Tue, 17 Oct 2017 14:53:52 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     Wei Wang <weiwan@...gle.com>
CC:     Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: Re: [PATCH net-next 2/3] ipv6: start fib6 gc on RTF_CACHE dst
 creation

On Tue, Oct 17, 2017 at 06:35:13PM +0000, Wei Wang wrote:
> On Tue, Oct 17, 2017 at 10:40 AM, Paolo Abeni <pabeni@...hat.com> wrote:
> > After the commit Fixes: 2b760fcf5cfb ("ipv6: hook up exception
> > table to store dst cache"), the fib6 gc is not started after
> > the creation of a RTF_CACHE via a redirect or pmtu update, since
> > fib6_add() isn't invoked anymore for such dsts.
Nice catch!

Acked-by: Martin KaFai Lau <kafai@...com>

> >
> > We need the fib6 gc to run periodically to clean the RTF_CACHE,
> > or the dst will stay there forever.
> >
> > Fix it by explicitly calling fib6_force_start_gc() on successful
> > exception creation. gc_args->more accounting will ensure that
> > the gc timer will run for whatever time needed to properly
> > clean the table.
> >
> > Fixes: 2b760fcf5cfb ("ipv6: hook up exception table to store dst cache")
> > Signed-off-by: Paolo Abeni <pabeni@...hat.com>
> > ---
> Acked-by: Wei Wang <weiwan@...gle.com>
> 
> Totally true. Thanks for catching this.
> 
> >  net/ipv6/route.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> > index 5bb53dbd4fd3..8b25a31b6b03 100644
> > --- a/net/ipv6/route.c
> > +++ b/net/ipv6/route.c
> > @@ -1340,8 +1340,10 @@ static int rt6_insert_exception(struct rt6_info *nrt,
> >         spin_unlock_bh(&rt6_exception_lock);
> >
> >         /* Update fn->fn_sernum to invalidate all cached dst */
> > -       if (!err)
> > +       if (!err) {
> >                 fib6_update_sernum(ort);
> > +               fib6_force_start_gc(net);
> > +       }
> >
> >         return err;
> >  }
> > --
> > 2.13.6
> >