net: dsa: introduce bridge notifier

A slave device will now notify the switch fabric once its port is
bridged or unbridged, instead of calling directly its switch operations.

This code allows propagating cross-chip bridging events in the fabric.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 71 insertions, 11 deletions

diff --git a/include/net/dsa.h b/include/net/dsa.h
index ac4ea7c3a102..e9c940c8936f 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -268,6 +268,16 @@ struct switchdev_obj_port_fdb;
 struct switchdev_obj_port_mdb;
 struct switchdev_obj_port_vlan;
 
+#define DSA_NOTIFIER_BRIDGE_JOIN                1
+#define DSA_NOTIFIER_BRIDGE_LEAVE               2
+
+/* DSA_NOTIFIER_BRIDGE_* */
+struct dsa_notifier_bridge_info {
+        struct net_device *br;
+        int sw_index;
+        int port;
+};
+
 struct dsa_switch_ops {
         /*
          * Probing and setup.
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index d8c3c0f00cf3..061a49c29cef 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -27,6 +27,17 @@
 
 static bool dsa_slave_dev_check(struct net_device *dev);
 
+static int dsa_slave_notify(struct net_device *dev, unsigned long e, void *v)
+{
+        struct dsa_slave_priv *p = netdev_priv(dev);
+        struct raw_notifier_head *nh = &p->dp->ds->dst->nh;
+        int err;
+
+        err = raw_notifier_call_chain(nh, e, v);
+
+        return notifier_to_errno(err);
+}
+
 /* slave mii_bus handling ***************************************************/
 static int dsa_slave_phy_read(struct mii_bus *bus, int addr, int reg)
 {
@@ -562,39 +573,46 @@ static int dsa_slave_bridge_port_join(struct net_device *dev,
                                       struct net_device *br)
 {
         struct dsa_slave_priv *p = netdev_priv(dev);
-        struct dsa_switch *ds = p->dp->ds;
-        int ret = -EOPNOTSUPP;
+        struct dsa_notifier_bridge_info info = {
+                .sw_index = p->dp->ds->index,
+                .port = p->dp->index,
+                .br = br,
+        };
+        int err;
 
         /* Here the port is already bridged. Reflect the current configuration
          * so that drivers can program their chips accordingly.
          */
         p->dp->bridge_dev = br;
 
-        if (ds->ops->port_bridge_join)
-                ret = ds->ops->port_bridge_join(ds, p->dp->index, br);
+        err = dsa_slave_notify(dev, DSA_NOTIFIER_BRIDGE_JOIN, &info);
 
         /* The bridging is rolled back on error */
-        if (ret && ret != -EOPNOTSUPP) {
+        if (err)
                 p->dp->bridge_dev = NULL;
-                return ret;
-        }
 
-        return 0;
+        return err;
 }
 
 static void dsa_slave_bridge_port_leave(struct net_device *dev,
                                         struct net_device *br)
 {
         struct dsa_slave_priv *p = netdev_priv(dev);
-        struct dsa_switch *ds = p->dp->ds;
+        struct dsa_notifier_bridge_info info = {
+                .sw_index = p->dp->ds->index,
+                .port = p->dp->index,
+                .br = br,
+        };
+        int err;
 
         /* Here the port is already unbridged. Reflect the current configuration
          * so that drivers can program their chips accordingly.
          */
         p->dp->bridge_dev = NULL;
 
-        if (ds->ops->port_bridge_leave)
-                ds->ops->port_bridge_leave(ds, p->dp->index, br);
+        err = dsa_slave_notify(dev, DSA_NOTIFIER_BRIDGE_LEAVE, &info);
+        if (err)
+                netdev_err(dev, "failed to notify DSA_NOTIFIER_BRIDGE_LEAVE\n");
 
         /* Port left the bridge, put in BR_STATE_DISABLED by the bridge layer,
          * so allow it to be in BR_STATE_FORWARDING to be kept functional
diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index e22fa7633d03..6456dacf9ae9 100644
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c
@@ -13,6 +13,32 @@
 #include <linux/notifier.h>
 #include <net/dsa.h>
 
+static int dsa_switch_bridge_join(struct dsa_switch *ds,
+                                  struct dsa_notifier_bridge_info *info)
+{
+        if (ds->index == info->sw_index && ds->ops->port_bridge_join)
+                return ds->ops->port_bridge_join(ds, info->port, info->br);
+
+        if (ds->index != info->sw_index)
+                dev_dbg(ds->dev, "crosschip DSA port %d.%d bridged to %s\n",
+                        info->sw_index, info->port, netdev_name(info->br));
+
+        return 0;
+}
+
+static int dsa_switch_bridge_leave(struct dsa_switch *ds,
+                                   struct dsa_notifier_bridge_info *info)
+{
+        if (ds->index == info->sw_index && ds->ops->port_bridge_leave)
+                ds->ops->port_bridge_leave(ds, info->port, info->br);
+
+        if (ds->index != info->sw_index)
+                dev_dbg(ds->dev, "crosschip DSA port %d.%d unbridged from %s\n",
+                        info->sw_index, info->port, netdev_name(info->br));
+
+        return 0;
+}
+
 static int dsa_switch_event(struct notifier_block *nb,
                             unsigned long event, void *info)
 {
@@ -20,6 +46,12 @@ static int dsa_switch_event(struct notifier_block *nb,
         int err;
 
         switch (event) {
+        case DSA_NOTIFIER_BRIDGE_JOIN:
+                err = dsa_switch_bridge_join(ds, info);
+                break;
+        case DSA_NOTIFIER_BRIDGE_LEAVE:
+                err = dsa_switch_bridge_leave(ds, info);
+                break;
         default:
                 err = -EOPNOTSUPP;
                 break;