[NET-PREV,34/51] dsa: Make all switch tree ports relate to same nd_lock

Commit Message

Kirill Tkhai March 22, 2025, 2:42 p.m. UTC

dsa_tree_migrate_ports_from_lag_conduit() may take any
of ports as new conduit, and it will be connected to
the rest of ports (and using netdev_upper_dev_link()),
so all of them must share the same nd_lock.

xxx: Keep in mind NETDEV_CHANGEUPPER is called
     by netdev_upper_dev_unlink().

Signed-off-by: Kirill Tkhai <[e-mail]>
---
 net/dsa/dsa.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

Patch

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 668c729946ea..6468b03d3d46 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -1156,6 +1156,8 @@  static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *conduit,
 	struct dsa_switch *ds = dp->ds;
 	struct dsa_switch_tree *dst = ds->dst;
 	enum dsa_tag_protocol default_proto;
+	struct nd_lock *nd_lock, *nd_lock2;
+	struct dsa_port *first_dp;
 
 	/* Find out which protocol the switch would prefer. */
 	default_proto = dsa_get_tag_protocol(dp, conduit);
@@ -1213,6 +1215,18 @@  static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *conduit,
 		dst->tag_ops = tag_ops;
 	}
 
+	first_dp = dsa_tree_find_first_cpu(dst);
+	if (first_dp && first_dp->conduit) {
+		/* All conduits must relate the same nd_lock
+		 * since dsa_tree_migrate_ports_from_lag_conduit()
+		 * may take any of them from list.
+		 */
+		double_lock_netdev(first_dp->conduit, &nd_lock,
+				   conduit, &nd_lock2);
+		nd_lock_transfer_devices(&nd_lock, &nd_lock2);
+		double_unlock_netdev(nd_lock, nd_lock2);
+	}
+
 	dp->conduit = conduit;
 	dp->type = DSA_PORT_TYPE_CPU;
 	dsa_port_set_tag_protocol(dp, dst->tag_ops);