netdev - Re: [PATCH v2] vlan: allow nested vlan_do

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Date:	Sun, 30 Oct 2011 09:38:12 +0100
From:	Jiri Pirko <jpirko@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	John Fastabend <john.r.fastabend@...el.com>,
	David Miller <davem@...emloft.net>,
	"jesse@...ira.com" <jesse@...ira.com>,
	"hans.schillstrom@...csson.com" <hans.schillstrom@...csson.com>,
	"mbizon@...ebox.fr" <mbizon@...ebox.fr>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"fubar@...ibm.com" <fubar@...ibm.com>
Subject: Re: [PATCH v2] vlan: allow nested vlan_do_receive()

Sat, Oct 29, 2011 at 06:28:40PM CEST, jpirko@...hat.com wrote:
>Sat, Oct 29, 2011 at 06:13:39PM CEST, eric.dumazet@...il.com wrote:
>>commit 2425717b27eb (net: allow vlan traffic to be received under bond)
>>broke ARP processing on vlan on top of bonding.
>>
>>       +-------+
>>eth0 --| bond0 |---bond0.103
>>eth1 --|       |
>>       +-------+
>>
>>52870.115435: skb_gro_reset_offset <-napi_gro_receive
>>52870.115435: dev_gro_receive <-napi_gro_receive
>>52870.115435: napi_skb_finish <-napi_gro_receive
>>52870.115435: netif_receive_skb <-napi_skb_finish
>>52870.115435: get_rps_cpu <-netif_receive_skb
>>52870.115435: __netif_receive_skb <-netif_receive_skb
>>52870.115436: vlan_do_receive <-__netif_receive_skb
>>52870.115436: bond_handle_frame <-__netif_receive_skb
>>52870.115436: vlan_do_receive <-__netif_receive_skb
>>52870.115436: arp_rcv <-__netif_receive_skb
>>52870.115436: kfree_skb <-arp_rcv
>>
>>Packet is dropped in arp_rcv() because its pkt_type was set to
>>PACKET_OTHERHOST in the first vlan_do_receive() call, since no eth0.103
>>exists.
>>
>>We really need to change pkt_type only if no more rx_handler is about to
>>be called for the packet.
>>
>>Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
>>---
>>V2 : change the vlan_do_receive() added argument to be a boolean
>>
>> include/linux/if_vlan.h |    6 +++---
>> net/8021q/vlan_core.c   |    7 +++++--
>> net/core/dev.c          |    4 ++--
>> 3 files changed, 10 insertions(+), 7 deletions(-)
>>
>>diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
>>index 44da482..12d5543 100644
>>--- a/include/linux/if_vlan.h
>>+++ b/include/linux/if_vlan.h
>>@@ -106,7 +106,7 @@ extern struct net_device *__vlan_find_dev_deep(struct net_device *real_dev,
>> extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
>> extern u16 vlan_dev_vlan_id(const struct net_device *dev);
>> 
>>-extern bool vlan_do_receive(struct sk_buff **skb);
>>+extern bool vlan_do_receive(struct sk_buff **skb, bool last_handler);
>> extern struct sk_buff *vlan_untag(struct sk_buff *skb);
>> 
>> #else
>>@@ -128,9 +128,9 @@ static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
>> 	return 0;
>> }
>> 
>>-static inline bool vlan_do_receive(struct sk_buff **skb)
>>+static inline bool vlan_do_receive(struct sk_buff **skb, bool last_handler)
>> {
>>-	if ((*skb)->vlan_tci & VLAN_VID_MASK)
>>+	if (((*skb)->vlan_tci & VLAN_VID_MASK) && last_handler)
>> 		(*skb)->pkt_type = PACKET_OTHERHOST;
>> 	return false;
>> }
>>diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
>>index f1f2f7b..163397f 100644
>>--- a/net/8021q/vlan_core.c
>>+++ b/net/8021q/vlan_core.c
>>@@ -4,7 +4,7 @@
>> #include <linux/netpoll.h>
>> #include "vlan.h"
>> 
>>-bool vlan_do_receive(struct sk_buff **skbp)
>>+bool vlan_do_receive(struct sk_buff **skbp, bool last_handler)
>> {
>> 	struct sk_buff *skb = *skbp;
>> 	u16 vlan_id = skb->vlan_tci & VLAN_VID_MASK;
>>@@ -13,7 +13,10 @@ bool vlan_do_receive(struct sk_buff **skbp)
>> 
>> 	vlan_dev = vlan_find_dev(skb->dev, vlan_id);
>> 	if (!vlan_dev) {
>>-		if (vlan_id)
>>+		/* Only the last call to vlan_do_receive() should change
>>+		 * pkt_type to PACKET_OTHERHOST
>>+		 */
>>+		if (vlan_id && last_handler)
>> 			skb->pkt_type = PACKET_OTHERHOST;
>> 		return false;
>> 	}
>>diff --git a/net/core/dev.c b/net/core/dev.c
>>index edcf019..6ba50a1 100644
>>--- a/net/core/dev.c
>>+++ b/net/core/dev.c
>>@@ -3283,18 +3283,18 @@ another_round:
>> ncls:
>> #endif
>> 
>>+	rx_handler = rcu_dereference(skb->dev->rx_handler);
>> 	if (vlan_tx_tag_present(skb)) {
>> 		if (pt_prev) {
>> 			ret = deliver_skb(skb, pt_prev, orig_dev);
>> 			pt_prev = NULL;
>> 		}
>>-		if (vlan_do_receive(&skb))
>>+		if (vlan_do_receive(&skb, !rx_handler))
>
>This I had on mind as well. Looks nicer. I have one another thought how
>to resolve this. I will try it and let you know by tomorrow.

Okay that would not work.

So I'm okay with this patch 


Reviewed-by: Jiri Pirko <jpirko@...hat.com>


>
>Jirka
>
>> 			goto another_round;
>> 		else if (unlikely(!skb))
>> 			goto out;
>> 	}
>> 
>>-	rx_handler = rcu_dereference(skb->dev->rx_handler);
>> 	if (rx_handler) {
>> 		if (pt_prev) {
>> 			ret = deliver_skb(skb, pt_prev, orig_dev);
>>
>>
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