On 26.09.2016 03:35, Florian Westphal wrote: > Jamal Hadi Salim <j...@mojatatu.com> wrote: >> On 16-09-25 02:31 PM, Florian Westphal wrote: >>> Shmulik Ladkani <shmulik.ladk...@gmail.com> wrote: >>>> We can later address any loop-detection improvements in mirred. >>>> WDYT? >>> >>> You can address this after fixing infamous spinlock recursion hard >>> lockup (which has existed forever): >>> >>> tc qdisc add dev eth0 root handle 1: prio >>> tc filter add dev eth0 parent 1: protocol ip u32 match u32 0 0 flowid >>> 1:2 action mirred egress redirect dev eth0 >>> >>> (only do this on toy vm) >>> >> >> Realize didnt respond to this. Seems very simple to fix: >> if skb->dev->ifindex and m->tcfm_dev->ifindex are the >> same, then you can drop the packet. > > Yes, but I think we get same issue when we deal with stacked > interfaces, and redirect is to e.g. vlan on top of physical device.
We do have the adjacent upper lists in all netdevices, calculating if a mirred actions would insert the skb on a stacked device above us should be as easy as querying netdev_has_upper_dev and should be possible to check that during config time. > And we have such loops even without tc, for instance when placing > both veth ends in same bridge :-( We can't fix that without a ttl in the sk_buff struct. Bye, Hannes
