Messages in this thread | | | From | Brendan Higgins <> | Date | Thu, 25 Oct 2018 14:46:50 -0700 | Subject | Re: [PATCH v1] net: ipv6: fix racey clock check in route cache aging logic |
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On Thu, Oct 25, 2018 at 2:40 PM Eric Dumazet <eric.dumazet@gmail.com> wrote: > On 10/25/2018 02:13 PM, Brendan Higgins wrote: <snip> > > > > diff --git a/net/ipv6/route.c b/net/ipv6/route.c > > index 2a7423c394560..54d28b91fd840 100644 > > --- a/net/ipv6/route.c > > +++ b/net/ipv6/route.c > > @@ -1734,7 +1734,7 @@ static void rt6_age_examine_exception(struct rt6_exception_bucket *bucket, > > rt6_remove_exception(bucket, rt6_ex); > > return; > > } > > - } else if (time_after(jiffies, rt->dst.expires)) { > > + } else if (time_after(now, rt->dst.expires)) { > > RT6_TRACE("purging expired route %p\n", rt); > > rt6_remove_exception(bucket, rt6_ex); > > return; > > > > > I do not think there is a bug here ? > > As a matter of fact, using the latest value of jiffies is probably better, > since in some cases the @now variable could be quite in the past.
Then why do we pass the `now` parameter in at all and use it at all, like here: https://elixir.bootlin.com/linux/latest/source/net/ipv6/route.c#L1764 ?
I am still skeptical that we should check jiffies in each check, but we should at least be consistent.
Cheers
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