Patrick McHardy wrote: > Urs Thuermann wrote: > >> * Use skb->iif instead of skb->cb to pass receiving interface from >> raw_rcv() and bcm_rcv() up to raw_recvmsg() and bcm_recvmsg(). >> > > > skb->iif doesn't necessarily point to the incoming network device > as seen seen by netif_receive_skb, for layered devices it currently > always points to the first interface that received a packet. >
This is exactly the intention. > Its so far also only used for traffic classification, please explain > how you're using it and what values it is set to on which paths. > As you might have seen in Documentation/networking/can.txt (hint, hint, hint!) the CAN has no routing, no ARP, no MAC adressing and is a broadcast only medium. So if there is (at least) any reasonable addressing on CAN it consists of the CAN-frame's "CAN-Identifier" and the CAN-bus this CAN-frame is sent/received on. For this reason the information about the interface the CAN-frame has been received on has to be made available to the user-application if it needs this information. Until your hint about our skb->cb missusage, we (successfully) transported this information inside skb->cb to socket-level. But indeed skb->iif is the better (and in our opinion the right) place to transport this information inside the skb to the socket-level. In both cases (receiving real CAN-frames from the CAN-netdev / performing the loopback of CAN-frames) we set skb->iif to zero to let netif_receive_skb() set the iif-value to the current skb->dev index. So skb->iif is set to the first interface the CAN-frame is received on, which is what we need & intended here. Is it the right approach to let netif_receive_skb() set the iif-value or should we better set this value on our own before invoking netif_rx()? Best regards, Oliver - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
