[PATCH v2 net-next 3/9] net: bridge: move DSA master bridging restriction to DSA

Vladimir Oltean
2022-08-18T13:54:51Z

When DSA gains support for multiple CPU ports in a LAG, it will become
mandatory to monitor the changeupper events for the DSA master.

In fact, there are already some restrictions to be imposed in that area,
namely that a DSA master cannot be a bridge port except in some special
circumstances.

Centralize the restrictions at the level of the DSA layer as a
preliminary step.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
---
v1->v2: none

net/bridge/br_if.c | 20 --------------------
net/dsa/slave.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+), 20 deletions(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index a84a7cfb9d6d..efbd93e92ce2 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -568,26 +568,6 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
!is_valid_ether_addr(dev->dev_addr))
return -EINVAL;

- /* Also don't allow bridging of net devices that are DSA masters, since
- * the bridge layer rx_handler prevents the DSA fake ethertype handler
- * to be invoked, so we don't get the chance to strip off and parse the
- * DSA switch tag protocol header (the bridge layer just returns
- * RX_HANDLER_CONSUMED, stopping RX processing for these frames).
- * The only case where that would not be an issue is when bridging can
- * already be offloaded, such as when the DSA master is itself a DSA
- * or plain switchdev port, and is bridged only with other ports from
- * the same hardware device.
- */
- if (netdev_uses_dsa(dev)) {
- list_for_each_entry(p, &br->port_list, list) {
- if (!netdev_port_same_parent_id(dev, p->dev)) {
- NL_SET_ERR_MSG(extack,
- "Cannot do software bridging with a DSA master");
- return -EINVAL;
- }
- }
- }
-
/* No bridging of bridges */
if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit) {
NL_SET_ERR_MSG(extack,
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 008bbe1c0285..09767f4b3b37 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -2699,6 +2699,46 @@ dsa_slave_prechangeupper_sanity_check(struct net_device *dev,
return NOTIFY_DONE;
}

+/* Don't allow bridging of DSA masters, since the bridge layer rx_handler
+ * prevents the DSA fake ethertype handler to be invoked, so we don't get the
+ * chance to strip off and parse the DSA switch tag protocol header (the bridge
+ * layer just returns RX_HANDLER_CONSUMED, stopping RX processing for these
+ * frames).
+ * The only case where that would not be an issue is when bridging can already
+ * be offloaded, such as when the DSA master is itself a DSA or plain switchdev
+ * port, and is bridged only with other ports from the same hardware device.
+ */
+static int
+dsa_bridge_prechangelower_sanity_check(struct net_device *new_lower,
+ struct netdev_notifier_changeupper_info *info)
+{
+ struct net_device *br = info->upper_dev;
+ struct netlink_ext_ack *extack;
+ struct net_device *lower;
+ struct list_head *iter;
+
+ if (!netif_is_bridge_master(br))
+ return NOTIFY_DONE;
+
+ if (!info->linking)
+ return NOTIFY_DONE;
+
+ extack = netdev_notifier_info_to_extack(&info->info);
+
+ netdev_for_each_lower_dev(br, lower, iter) {
+ if (!netdev_uses_dsa(new_lower) && !netdev_uses_dsa(lower))
+ continue;
+
+ if (!netdev_port_same_parent_id(lower, new_lower)) {
+ NL_SET_ERR_MSG(extack,
+ "Cannot do software bridging with a DSA master");
+ return notifier_from_errno(-EINVAL);
+ }
+ }
+
+ return NOTIFY_DONE;
+}
+
static int dsa_slave_netdevice_event(struct notifier_block *nb,
unsigned long event, void *ptr)
{
@@ -2713,6 +2753,10 @@ static int dsa_slave_netdevice_event(struct notifier_block *nb,
if (notifier_to_errno(err))
return err;

+ err = dsa_bridge_prechangelower_sanity_check(dev, info);
+ if (notifier_to_errno(err))
+ return err;
+
err = dsa_slave_prechangeupper(dev, ptr);
if (notifier_to_errno(err))
return err;
--
2.34.1