From f7cf972f9375388838b0fbdaa007ce8494646990 Mon Sep 17 00:00:00 2001 From: Tobias Waldekranz Date: Wed, 21 Jul 2021 19:23:59 +0300 Subject: [PATCH] net: bridge: disambiguate offload_fwd_mark Before this change, four related - but distinct - concepts where named offload_fwd_mark: - skb->offload_fwd_mark: Set by the switchdev driver if the underlying hardware has already forwarded this frame to the other ports in the same hardware domain. - nbp->offload_fwd_mark: An idetifier used to group ports that share the same hardware forwarding domain. - br->offload_fwd_mark: Counter used to make sure that unique IDs are used in cases where a bridge contains ports from multiple hardware domains. - skb->cb->offload_fwd_mark: The hardware domain on which the frame ingressed and was forwarded. Introduce the term "hardware forwarding domain" ("hwdom") in the bridge to denote a set of ports with the following property: If an skb with skb->offload_fwd_mark set, is received on a port belonging to hwdom N, that frame has already been forwarded to all other ports in hwdom N. By decoupling the name from "offload_fwd_mark", we can extend the term's definition in the future - e.g. to add constraints that describe expected egress behavior - without overloading the meaning of "offload_fwd_mark". - nbp->offload_fwd_mark thus becomes nbp->hwdom. - br->offload_fwd_mark becomes br->last_hwdom. - skb->cb->offload_fwd_mark becomes skb->cb->src_hwdom. The slight change in naming here mandates a slight change in behavior of the nbp_switchdev_frame_mark() function. Previously, it only set this value in skb->cb for packets with skb->offload_fwd_mark true (ones which were forwarded in hardware). Whereas now we always track the incoming hwdom for all packets coming from a switchdev (even for the packets which weren't forwarded in hardware, such as STP BPDUs, IGMP reports etc). As all uses of skb->cb->offload_fwd_mark were already gated behind checks of skb->offload_fwd_mark, this will not introduce any functional change, but it paves the way for future changes where the ingressing hwdom must be known for frames coming from a switchdev regardless of whether they were forwarded in hardware or not (basically, if the skb comes from a switchdev, skb->cb->src_hwdom now always tracks which one). A typical example where this is relevant: the switchdev has a fixed configuration to trap STP BPDUs, but STP is not running on the bridge and the group_fwd_mask allows them to be forwarded. Say we have this setup: br0 / | \ / | \ swp0 swp1 swp2 A BPDU comes in on swp0 and is trapped to the CPU; the driver does not set skb->offload_fwd_mark. The bridge determines that the frame should be forwarded to swp{1,2}. It is imperative that forward offloading is _not_ allowed in this case, as the source hwdom is already "poisoned". Recording the source hwdom allows this case to be handled properly. v2->v3: added code comments v3->v6: none Signed-off-by: Tobias Waldekranz Signed-off-by: Vladimir Oltean Reviewed-by: Grygorii Strashko Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- net/bridge/br_if.c | 2 +- net/bridge/br_private.h | 21 ++++++++++++++++----- net/bridge/br_switchdev.c | 16 ++++++++-------- 3 files changed, 25 insertions(+), 14 deletions(-) diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c index 6e4a323..838a277 100644 --- a/net/bridge/br_if.c +++ b/net/bridge/br_if.c @@ -643,7 +643,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev, if (err) goto err5; - err = nbp_switchdev_mark_set(p); + err = nbp_switchdev_hwdom_set(p); if (err) goto err6; diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index 30be9d0..25afbb3 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -386,7 +386,10 @@ struct net_bridge_port { struct netpoll *np; #endif #ifdef CONFIG_NET_SWITCHDEV - int offload_fwd_mark; + /* Identifier used to group ports that share the same switchdev + * hardware domain. + */ + int hwdom; #endif u16 group_fwd_mask; u16 backup_redirected_cnt; @@ -510,7 +513,10 @@ struct net_bridge { u32 auto_cnt; #ifdef CONFIG_NET_SWITCHDEV - int offload_fwd_mark; + /* Counter used to make sure that hardware domains get unique + * identifiers in case a bridge spans multiple switchdev instances. + */ + int last_hwdom; #endif struct hlist_head fdb_list; @@ -540,7 +546,12 @@ struct br_input_skb_cb { #endif #ifdef CONFIG_NET_SWITCHDEV - int offload_fwd_mark; + /* The switchdev hardware domain from which this packet was received. + * If skb->offload_fwd_mark was set, then this packet was already + * forwarded by hardware to the other ports in the source hardware + * domain, otherwise it wasn't. + */ + int src_hwdom; #endif }; @@ -1829,7 +1840,7 @@ static inline void br_sysfs_delbr(struct net_device *dev) { return; } /* br_switchdev.c */ #ifdef CONFIG_NET_SWITCHDEV -int nbp_switchdev_mark_set(struct net_bridge_port *p); +int nbp_switchdev_hwdom_set(struct net_bridge_port *p); void nbp_switchdev_frame_mark(const struct net_bridge_port *p, struct sk_buff *skb); bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p, @@ -1849,7 +1860,7 @@ static inline void br_switchdev_frame_unmark(struct sk_buff *skb) skb->offload_fwd_mark = 0; } #else -static inline int nbp_switchdev_mark_set(struct net_bridge_port *p) +static inline int nbp_switchdev_hwdom_set(struct net_bridge_port *p) { return 0; } diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c index d3adee0..833fd30 100644 --- a/net/bridge/br_switchdev.c +++ b/net/bridge/br_switchdev.c @@ -8,20 +8,20 @@ #include "br_private.h" -static int br_switchdev_mark_get(struct net_bridge *br, struct net_device *dev) +static int br_switchdev_hwdom_get(struct net_bridge *br, struct net_device *dev) { struct net_bridge_port *p; /* dev is yet to be added to the port list. */ list_for_each_entry(p, &br->port_list, list) { if (netdev_port_same_parent_id(dev, p->dev)) - return p->offload_fwd_mark; + return p->hwdom; } - return ++br->offload_fwd_mark; + return ++br->last_hwdom; } -int nbp_switchdev_mark_set(struct net_bridge_port *p) +int nbp_switchdev_hwdom_set(struct net_bridge_port *p) { struct netdev_phys_item_id ppid = { }; int err; @@ -35,7 +35,7 @@ int nbp_switchdev_mark_set(struct net_bridge_port *p) return err; } - p->offload_fwd_mark = br_switchdev_mark_get(p->br, p->dev); + p->hwdom = br_switchdev_hwdom_get(p->br, p->dev); return 0; } @@ -43,15 +43,15 @@ int nbp_switchdev_mark_set(struct net_bridge_port *p) void nbp_switchdev_frame_mark(const struct net_bridge_port *p, struct sk_buff *skb) { - if (skb->offload_fwd_mark && !WARN_ON_ONCE(!p->offload_fwd_mark)) - BR_INPUT_SKB_CB(skb)->offload_fwd_mark = p->offload_fwd_mark; + if (p->hwdom) + BR_INPUT_SKB_CB(skb)->src_hwdom = p->hwdom; } bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p, const struct sk_buff *skb) { return !skb->offload_fwd_mark || - BR_INPUT_SKB_CB(skb)->offload_fwd_mark != p->offload_fwd_mark; + BR_INPUT_SKB_CB(skb)->src_hwdom != p->hwdom; } /* Flags that can be offloaded to hardware */ -- 2.7.4