From: Oliver Hartkopp <socketcan@hartkopp•net>
To: Jiri Pirko <jiri@resnulli•us>
Cc: David Miller <davem@davemloft•net>,
Linux Netdev List <netdev@vger•kernel.org>
Subject: Re: [RFC davem] revert: net: Make skb->skb_iif always track skb->dev
Date: Sat, 12 Jan 2013 19:40:33 +0100 [thread overview]
Message-ID: <50F1AE21.90701@hartkopp.net> (raw)
In-Reply-To: <20130112181307.GA1567@minipsycho.orion>
Hello Jiri,
On 12.01.2013 19:13, Jiri Pirko wrote:
> Sat, Jan 12, 2013 at 02:48:14PM CET, socketcan@hartkopp•net wrote:
>> Hello Dave,
>>
>> in your below patch from 23 Jul 2012 you removed the check for an already set
>> value of skb_iif in net/core/dev.c
>>
>> I'm currently working on a solution to prevent some routed CAN frames to be
>> sent back onto the originating network device.
>
> Hm, I'm not sure where exactly you want to use this information, but
> can_rcv() can get it from orig_dev->ifindex
No - it's not in can_rcv() ...
Depending on the filter lists in can_rcv() the received skb is passed to the
function can_can_gw_rcv() in net/can/gw.c.
An there i wanted to add this code to omit sending the CAN frame on the
originating interface:
@@ .. @@ static void can_can_gw_rcv(struct sk_buff *skb, void *data
if (!(gwj->dst.dev->flags & IFF_UP)) {
gwj->dropped_frames++;
return;
}
+ /* is sending the skb back to the incoming interface allowed? */
+ if (!(gwj->flags & CGW_FLAGS_CAN_IIF_TX_OK) &&
+ skb->skb_iif == gwj->dst.dev->ifindex)
+ return;
+
/*
* clone the given skb, which has not been done in can_rcv()
*
This works fine, when the patch from Dave is reverted.
I did not find any good solution to preserve the originating netdev over
several netif_receive_skb() calls - but this skb_iif which has been made
unusable ...
(..)
>>
>> To me it is not clear why skb_iff is needed anyway as the value should
>> always be available via skb->dev->ifindex, right?
>>
>> But if skb_iff has any right to exist it should contain the first incoming
>> interface on the host IMO.
>>
>> Please correct my if i'm wrong and/or tell me what your commit message means
>> in respect to my request and why skb->dev->ifindex is not used instead of
>> skb_iif. I feel somehow lost about the skb_iif intention ...
>
> I believe that skb_iif should be removed.
AFAICS skb->skb_iif is used as some kind of cached variable for the original
skb->dev->ifindex - or is it really possible that skb->skb_iif is set while
skb->dev->ifindex is not accessible?
Btw. i my case skb_iif would make sense though.
Regards,
Oliver
>>
>> ---
>>
>>
>> http://git.kernel.org/?p=linux/kernel/git/davem/net-next.git;a=commitdiff;h=b68581778cd0051a3fb9a2b614dee7eccb5127ff
>>
>> net: Make skb->skb_iif always track skb->dev
>>
>> Make it follow device decapsulation, from things such as VLAN and
>> bonding.
>>
>> The stuff that actually cares about pre-demuxed device pointers, is
>> handled by the "orig_dev" variable in __netif_receive_skb(). And
>> the only consumer of that is the po->origdev feature of AF_PACKET
>> sockets.
>>
>> Signed-off-by: David S. Miller <davem@davemloft•net>
>> ---
>>
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index cca02ae..0ebaea1 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -3173,8 +3173,6 @@ static int __netif_receive_skb(struct sk_buff *skb)
>> if (netpoll_receive_skb(skb))
>> return NET_RX_DROP;
>>
>> - if (!skb->skb_iif)
>> - skb->skb_iif = skb->dev->ifindex;
>> orig_dev = skb->dev;
>>
>> skb_reset_network_header(skb);
>> @@ -3186,6 +3184,7 @@ static int __netif_receive_skb(struct sk_buff *skb)
>> rcu_read_lock();
>>
>> another_round:
>> + skb->skb_iif = skb->dev->ifindex;
>>
>> __this_cpu_inc(softnet_data.processed);
>>
>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
>> the body of a message to majordomo@vger•kernel.org
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next prev parent reply other threads:[~2013-01-12 18:40 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-12 13:48 [RFC davem] revert: net: Make skb->skb_iif always track skb->dev Oliver Hartkopp
2013-01-12 18:13 ` Jiri Pirko
2013-01-12 18:40 ` Oliver Hartkopp [this message]
2013-01-12 19:37 ` Jiri Pirko
2013-01-12 20:14 ` Oliver Hartkopp
2013-01-12 21:23 ` David Miller
2013-01-12 21:36 ` David Miller
2013-01-13 3:06 ` [PATCH net-next] pkt_sched: namespace aware ifb Eric Dumazet
2013-01-13 3:50 ` Benjamin LaHaise
2013-01-13 5:49 ` Eric Dumazet
2013-01-13 14:44 ` Jamal Hadi Salim
2013-01-13 16:41 ` Benjamin LaHaise
2013-01-13 16:57 ` Eric Dumazet
2013-01-13 17:25 ` Jamal Hadi Salim
2013-01-14 5:40 ` Eric Dumazet
2013-01-13 17:46 ` [PATCH net-next] ifb: dont hard code inet_net use Eric Dumazet
2013-01-14 13:13 ` Jamal Hadi Salim
2013-01-14 15:15 ` [PATCH net-next] pkt_sched: namespace aware act_mirred Benjamin LaHaise
2013-01-14 20:10 ` David Miller
2013-01-14 20:13 ` [PATCH net-next] ifb: dont hard code inet_net use David Miller
2013-01-13 14:59 ` [PATCH net-next] pkt_sched: namespace aware ifb Benjamin LaHaise
2013-01-13 16:35 ` Eric Dumazet
2013-01-13 11:01 ` [RFC davem] revert: net: Make skb->skb_iif always track skb->dev Oliver Hartkopp
2013-01-13 13:20 ` David Miller
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