Messages in this thread | | | From | Florian Fainelli <> | Subject | Re: [PATCH net-next v3 1/2] net: dsa: untag the bridge pvid from rx skbs | Date | Wed, 23 Sep 2020 21:27:36 -0700 |
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On 9/23/2020 4:08 PM, Vladimir Oltean wrote: > On Wed, Sep 23, 2020 at 03:59:46PM -0700, Florian Fainelli wrote: >> On 9/23/20 3:58 PM, Vladimir Oltean wrote: >>> On Wed, Sep 23, 2020 at 03:54:59PM -0700, Florian Fainelli wrote: >>>> Not having much luck with using __vlan_find_dev_deep_rcu() for a reason >>>> I don't understand we trip over the proto value being neither of the two >>>> support Ethertype and hit the BUG(). >>>> >>>> + upper_dev = __vlan_find_dev_deep_rcu(br, htons(proto), vid); >>>> + if (upper_dev) >>>> + return skb; >>>> >>>> Any ideas? >>> >>> Damn... >>> Yes, of course, the skb->protocol is still ETH_P_XDSA which is where >>> eth_type_trans() on the master left it. >> >> proto was obtained from br_vlan_get_proto() a few lines above, and >> br_vlan_get_proto() just returns br->vlan_proto which defaults to >> htons(ETH_P_8021Q) from br_vlan_init(). >> >> This is not skb->protocol that we are looking at AFAICT. > > Ok, my mistake. So what is the value of proto in vlan_proto_idx when it > fails? To me, the call path looks pretty pass-through for vlan_proto.
At the time we crash the proto value is indeed ETH_P_XDSA, but it is not because of the __vlan_find_dev_deep_rcu() call as I was mislead by the traces I was looking it (on ARMv7 the LR was pointing not where I was expecting it to), it is because of the following call trace:
netif_receive_skb_list_internal -> __netif_receive_skb_list_core -> __netif_receive_skb_core -> vlan_do_receive()
That function does use skb->vlan_proto to determine the VLAN group, at that point we have not set it but we did inherit skb->protocol instead which is ETH_P_XDSA.
The following does work though, tested with both br0 and a br0.1 upper:
+ upper_dev = __vlan_find_dev_deep_rcu(br, htons(proto), vid); + if (upper_dev) { + skb->vlan_proto = vlan_dev_vlan_proto(upper_dev); + return skb; }
I should have re-tested v2 and v3 with a bridge upper but I did not otherwise I would have caught that. If that sounds acceptable to you as well, I will submit that tomorrow.
Let me know what you think about the 802.1Q upper of a physical switch port in the other email. -- Florian
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