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Message-Id: <20210426170411.1789186-5-tobias@waldekranz.com>
Date: Mon, 26 Apr 2021 19:04:06 +0200
From: Tobias Waldekranz <tobias@...dekranz.com>
To: davem@...emloft.net, kuba@...nel.org
Cc: andrew@...n.ch, vivien.didelot@...il.com, f.fainelli@...il.com,
olteanv@...il.com, roopa@...dia.com, nikolay@...dia.com,
jiri@...nulli.us, idosch@...sch.org, stephen@...workplumber.org,
netdev@...r.kernel.org, bridge@...ts.linux-foundation.org
Subject: [RFC net-next 4/9] net: bridge: switchdev: Forward offloading
Allow switchdevs to forward frames from the CPU in accordance with the
bridge configuration in the same way as is done between bridge
ports. This means that the bridge will only send a single skb towards
one of the ports under the switchdev's control, and expects the driver
to deliver the packet to all eligible ports in its domain.
Primarily this improves the performance of multicast flows with
multiple subscribers, as it allows the hardware to perform the frame
replication.
The basic flow between the driver and the bridge is as follows:
- The switchdev accepts the offload by returning a non-null pointer
from .ndo_dfwd_add_station when the port is added to the bridge.
- The bridge sends offloadable skbs to one of the ports under the
switchdev's control using dev_queue_xmit_accel.
- The switchdev notices the offload by checking for a non-NULL
"sb_dev" in the core's call to .ndo_select_queue.
Signed-off-by: Tobias Waldekranz <tobias@...dekranz.com>
---
net/bridge/br_forward.c | 11 +++++++-
net/bridge/br_private.h | 27 ++++++++++++++++++
net/bridge/br_switchdev.c | 59 +++++++++++++++++++++++++++++++++++++--
3 files changed, 93 insertions(+), 4 deletions(-)
diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 6e9b049ae521..b4fb3b0bb1ec 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -32,6 +32,8 @@ static inline int should_deliver(const struct net_bridge_port *p,
int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
{
+ struct net_device *sb_dev = NULL;
+
skb_push(skb, ETH_HLEN);
if (!is_skb_forwardable(skb->dev, skb))
goto drop;
@@ -48,7 +50,10 @@ int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb
skb_set_network_header(skb, depth);
}
- dev_queue_xmit(skb);
+ if (br_switchdev_accels_skb(skb))
+ sb_dev = BR_INPUT_SKB_CB(skb)->brdev;
+
+ dev_queue_xmit_accel(skb, sb_dev);
return 0;
@@ -105,6 +110,8 @@ static void __br_forward(const struct net_bridge_port *to,
indev = NULL;
}
+ nbp_switchdev_frame_mark_accel(to, skb);
+
NF_HOOK(NFPROTO_BRIDGE, br_hook,
net, NULL, skb, indev, skb->dev,
br_forward_finish);
@@ -174,6 +181,8 @@ static struct net_bridge_port *maybe_deliver(
if (!should_deliver(p, skb))
return prev;
+ nbp_switchdev_frame_mark_fwd(p, skb);
+
if (!prev)
goto out;
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index aba92864d285..933e951b0d7a 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -332,6 +332,7 @@ struct net_bridge_port {
#endif
#ifdef CONFIG_NET_SWITCHDEV
int hwdom;
+ void *accel_priv;
#endif
u16 group_fwd_mask;
u16 backup_redirected_cnt;
@@ -506,7 +507,9 @@ struct br_input_skb_cb {
#endif
#ifdef CONFIG_NET_SWITCHDEV
+ u8 fwd_accel:1;
int src_hwdom;
+ br_hwdom_map_t fwd_hwdoms;
#endif
};
@@ -1597,6 +1600,15 @@ static inline void br_sysfs_delbr(struct net_device *dev) { return; }
/* br_switchdev.c */
#ifdef CONFIG_NET_SWITCHDEV
+static inline bool br_switchdev_accels_skb(struct sk_buff *skb)
+{
+ return BR_INPUT_SKB_CB(skb)->fwd_accel;
+}
+
+void nbp_switchdev_frame_mark_accel(const struct net_bridge_port *p,
+ struct sk_buff *skb);
+void nbp_switchdev_frame_mark_fwd(const struct net_bridge_port *p,
+ struct sk_buff *skb);
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,
@@ -1619,6 +1631,21 @@ static inline void br_switchdev_frame_unmark(struct sk_buff *skb)
skb->offload_fwd_mark = 0;
}
#else
+static inline bool br_switchdev_accels_skb(struct sk_buff *skb)
+{
+ return false;
+}
+
+static inline void nbp_switchdev_frame_mark_accel(const struct net_bridge_port *p,
+ struct sk_buff *skb)
+{
+}
+
+static inline void nbp_switchdev_frame_mark_fwd(const struct net_bridge_port *p,
+ struct sk_buff *skb)
+{
+}
+
static inline void nbp_switchdev_frame_mark(const struct net_bridge_port *p,
struct sk_buff *skb)
{
diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
index 54bd7205bfb5..c903171ad291 100644
--- a/net/bridge/br_switchdev.c
+++ b/net/bridge/br_switchdev.c
@@ -8,6 +8,26 @@
#include "br_private.h"
+static bool nbp_switchdev_can_accel(const struct net_bridge_port *p,
+ const struct sk_buff *skb)
+{
+ return p->accel_priv && (p->hwdom != BR_INPUT_SKB_CB(skb)->src_hwdom);
+}
+
+void nbp_switchdev_frame_mark_accel(const struct net_bridge_port *p,
+ struct sk_buff *skb)
+{
+ if (nbp_switchdev_can_accel(p, skb))
+ BR_INPUT_SKB_CB(skb)->fwd_accel = true;
+}
+
+void nbp_switchdev_frame_mark_fwd(const struct net_bridge_port *p,
+ struct sk_buff *skb)
+{
+ if (nbp_switchdev_can_accel(p, skb))
+ set_bit(p->hwdom, BR_INPUT_SKB_CB(skb)->fwd_hwdoms);
+}
+
void nbp_switchdev_frame_mark(const struct net_bridge_port *p,
struct sk_buff *skb)
{
@@ -18,8 +38,10 @@ void nbp_switchdev_frame_mark(const struct net_bridge_port *p,
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)->src_hwdom != p->hwdom;
+ struct br_input_skb_cb *cb = BR_INPUT_SKB_CB(skb);
+
+ return !test_bit(p->hwdom, cb->fwd_hwdoms) &&
+ (!skb->offload_fwd_mark || cb->src_hwdom != p->hwdom);
}
/* Flags that can be offloaded to hardware */
@@ -125,6 +147,27 @@ int br_switchdev_port_vlan_del(struct net_device *dev, u16 vid)
return switchdev_port_obj_del(dev, &v.obj);
}
+static void nbp_switchdev_fwd_offload_add(struct net_bridge_port *p)
+{
+ void *priv;
+
+ if (!(p->dev->features & NETIF_F_HW_L2FW_DOFFLOAD))
+ return;
+
+ priv = p->dev->netdev_ops->ndo_dfwd_add_station(p->dev, p->br->dev);
+ if (!IS_ERR_OR_NULL(priv))
+ p->accel_priv = priv;
+}
+
+static void nbp_switchdev_fwd_offload_del(struct net_bridge_port *p)
+{
+ if (!p->accel_priv)
+ return;
+
+ p->dev->netdev_ops->ndo_dfwd_del_station(p->dev, p->accel_priv);
+ p->accel_priv = NULL;
+}
+
static int nbp_switchdev_hwdom_set(struct net_bridge_port *joining)
{
struct net_bridge *br = joining->br;
@@ -176,13 +219,23 @@ int nbp_switchdev_add(struct net_bridge_port *p)
return err;
}
- return nbp_switchdev_hwdom_set(p);
+ err = nbp_switchdev_hwdom_set(p);
+ if (err)
+ return err;
+
+ if (p->hwdom)
+ nbp_switchdev_fwd_offload_add(p);
+
+ return 0;
}
void nbp_switchdev_del(struct net_bridge_port *p)
{
ASSERT_RTNL();
+ if (p->accel_priv)
+ nbp_switchdev_fwd_offload_del(p);
+
if (p->hwdom)
nbp_switchdev_hwdom_put(p);
}
--
2.25.1
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