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Message-ID: <1319904026.2586.42.camel@edumazet-laptop>
Date: Sat, 29 Oct 2011 18:00:26 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: Jiri Pirko <jpirko@...hat.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: [net-next PATCH] net: allow vlan traffic to be received under
bond
Le samedi 29 octobre 2011 à 16:59 +0200, Jiri Pirko a écrit :
> Sat, Oct 29, 2011 at 12:22:26PM CEST, eric.dumazet@...il.com wrote:
> >Le vendredi 28 octobre 2011 à 19:20 -0700, John Fastabend a écrit :
> >
> >> Thanks Eric! Thought about this some and I haven't come up
> >> with anything better yet. Even though this might be a slight
> >> hack I would prefer this to reverting the patch.
> >>
> >> I'll think about this more tomorrow. Would you be against
> >> submitting this patch?
> >
> >I cant submit this patch, because its a hack and partial fix.
> >
> >For Unicast packets, we still do the wrong thing : setting their
> >pkt_type to PACKET_OTHERHOST before the call to rx_handler :
> >
> >In this case, bond_handle_frame() wont handle this packet correctly in
> >some cases (BOND_MODE_ALB ...). I suppose bridge might be confused as
> >well. So other problems remain.
> >
> >We should delay the PACKET_OTHERHOST setting to the last moment, that is
> >the last time vlan_do_receive() is called.
> >
> >What about following patch instead ?
> >
> >[PATCH] vlan: allow nested vlan_do_receive()
> >
> >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>
> >---
> > include/linux/if_vlan.h | 8 +++++---
> > net/8021q/vlan_core.c | 7 +++++--
> > net/core/dev.c | 4 ++--
> > 3 files changed, 12 insertions(+), 7 deletions(-)
> >
> >diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
> >index 44da482..95874ff 100644
> >--- a/include/linux/if_vlan.h
> >+++ b/include/linux/if_vlan.h
> >@@ -106,7 +106,8 @@ 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,
> >+ rx_handler_func_t *rx_handler);
> > extern struct sk_buff *vlan_untag(struct sk_buff *skb);
> >
> > #else
> >@@ -128,9 +129,10 @@ 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,
> >+ rx_handler_func_t *rx_handler)
> > {
> >- if ((*skb)->vlan_tci & VLAN_VID_MASK)
> >+ if (((*skb)->vlan_tci & VLAN_VID_MASK) && !rx_handler)
> > (*skb)->pkt_type = PACKET_OTHERHOST;
> > return false;
> > }
> >diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
> >index f1f2f7b..3ec1ada 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, rx_handler_func_t *rx_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 && !rx_handler)
> > skb->pkt_type = PACKET_OTHERHOST;
> > return false;
> > }
> >diff --git a/net/core/dev.c b/net/core/dev.c
> >index edcf019..40976b4 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))
>
> I must say I do not like passing rx_handler out like this. Apart it's
> not nice, it might be misleading....
>
> How about something like following instead? I must test it but I believe
> it should resolve the problem.
>
>
> diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
> index 44da482..165a487 100644
> --- a/include/linux/if_vlan.h
> +++ b/include/linux/if_vlan.h
> @@ -130,8 +130,6 @@ static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
>
> static inline bool vlan_do_receive(struct sk_buff **skb)
> {
> - if ((*skb)->vlan_tci & VLAN_VID_MASK)
> - (*skb)->pkt_type = PACKET_OTHERHOST;
> return false;
> }
>
> @@ -141,6 +139,14 @@ static inline struct sk_buff *vlan_untag(struct sk_buff *skb)
> }
> #endif
>
> +static inline void vlan_handle_leftover(struct sk_buff *skb)
> +{
> + u16 vlan_id = skb->vlan_tci & VLAN_VID_MASK;
> +
> + if (vlan_id)
> + skb->pkt_type = PACKET_OTHERHOST;
> +}
> +
> /**
> * vlan_insert_tag - regular VLAN tag inserting
> * @skb: skbuff to tag
> diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
> index f1f2f7b..540da12 100644
> --- a/net/8021q/vlan_core.c
> +++ b/net/8021q/vlan_core.c
> @@ -12,11 +12,8 @@ bool vlan_do_receive(struct sk_buff **skbp)
> struct vlan_pcpu_stats *rx_stats;
>
> vlan_dev = vlan_find_dev(skb->dev, vlan_id);
> - if (!vlan_dev) {
> - if (vlan_id)
> - skb->pkt_type = PACKET_OTHERHOST;
> + if (!vlan_dev)
> return false;
> - }
>
> skb = *skbp = skb_share_check(skb, GFP_ATOMIC);
> if (unlikely(!skb))
> diff --git a/net/core/dev.c b/net/core/dev.c
> index b7ba81a..6fdfcc9 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -3314,6 +3314,14 @@ ncls:
> }
> }
>
> + if (vlan_tx_tag_present(skb)) {
> + /*
> + * Tag is still present here. That means there's no device
> + * set up for this vlan id. So handle these leftovers here.
> + */
> + vlan_handle_leftover(skb);
> + }
> +
> /* deliver only exact match when indicated */
> null_or_dev = deliver_exact ? skb->dev : NULL;
>
Hmm, is it really working ? where vlan_tci is cleared ?
This is indeed nice but adds another test in fast path, while in my
patch, additional tests are done in slow path only.
I see nothing wrong with passing rx_handler : Its probably cleaner than
adding rcu_dereference_raw(skb->dev->rx_handler) in the two
vlan_do_receive() implementations...
For reference, this was the first patch I had in mind, before I decided
that caller had to pass the rx_handler instead. (It could be a boolean
instead)
include/linux/if_vlan.h | 3 ++-
net/8021q/vlan_core.c | 5 ++++-
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 44da482..c6c00b4 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -130,7 +130,8 @@ static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
static inline bool vlan_do_receive(struct sk_buff **skb)
{
- if ((*skb)->vlan_tci & VLAN_VID_MASK)
+ if (((*skb)->vlan_tci & VLAN_VID_MASK) &&
+ !rcu_dereference_raw((*skb)->dev->rx_handler))
(*skb)->pkt_type = PACKET_OTHERHOST;
return false;
}
diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index f1f2f7b..245efb8 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -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 && !rcu_dereference_raw(skb->dev->rx_handler))
skb->pkt_type = PACKET_OTHERHOST;
return false;
}
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