bonding: support aggregator selection based on port priority

Add a new ad_select policy 'port_priority' that uses the per-port
actor priority values (set via ad_actor_port_prio) to determine
aggregator selection.

This allows administrators to influence which ports are preferred
for aggregation by assigning different priority values, providing
more flexible load balancing control in LACP configurations.

Signed-off-by: Hangbin Liu <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

Documentation/networking/bonding.rst

···
 		ports (slaves).  Reselection occurs as described under the
 		"bandwidth" setting, above.
 
-	The bandwidth and count selection policies permit failover of
-	802.3ad aggregations when partial failure of the active aggregator
-	occurs.  This keeps the aggregator with the highest availability
-	(either in bandwidth or in number of ports) active at all times.
+	actor_port_prio or 3
+
+		The active aggregator is chosen by the highest total sum of
+		actor port priorities across its active ports. Note this
+		priority is actor_port_prio, not per port prio, which is
+		used for primary reselect.
+
+	The bandwidth, count and actor_port_prio selection policies permit
+	failover of 802.3ad aggregations when partial failure of the active
+	aggregator occurs. This keeps the aggregator with the highest
+	availability (either in bandwidth, number of ports, or total value
+	of port priorities) active at all times.
 
 	This option was added in bonding version 3.4.0.
 

drivers/net/bonding/bond_3ad.c

···
 	return active;
 }
 
+static unsigned int __agg_ports_priority(const struct aggregator *agg)
+{
+	struct port *port = agg->lag_ports;
+	unsigned int prio = 0;
+
+	for (; port; port = port->next_port_in_aggregator)
+		if (port->is_enabled)
+			prio += port->actor_port_priority;
+
+	return prio;
+}
+
 /**
  * __get_agg_bandwidth - get the total bandwidth of an aggregator
  * @aggregator: the aggregator we're looking at
···
 	 * 4.  Therefore, current and best both have partner replies or
 	 *     both do not, so perform selection policy:
 	 *
+	 * BOND_AD_PRIO: Select by total priority of ports. If priority
+	 *     is equal, select by count.
+	 *
 	 * BOND_AD_COUNT: Select by count of ports.  If count is equal,
 	 *     select by bandwidth.
 	 *
···
 		return best;
 
 	switch (__get_agg_selection_mode(curr->lag_ports)) {
+	case BOND_AD_PRIO:
+		if (__agg_ports_priority(curr) > __agg_ports_priority(best))
+			return curr;
+
+		if (__agg_ports_priority(curr) < __agg_ports_priority(best))
+			return best;
+
+		fallthrough;
 	case BOND_AD_COUNT:
 		if (__agg_active_ports(curr) > __agg_active_ports(best))
 			return curr;
···
  * set of slaves in the bond changes.
  *
  * BOND_AD_COUNT: select the aggregator with largest number of ports
+ * (slaves), and reselect whenever a link state change takes place or the
+ * set of slaves in the bond changes.
+ *
+ * BOND_AD_PRIO: select the aggregator with highest total priority of ports
  * (slaves), and reselect whenever a link state change takes place or the
  * set of slaves in the bond changes.
  *

drivers/net/bonding/bond_options.c

···
 };
 
 static const struct bond_opt_value bond_ad_select_tbl[] = {
-	{ "stable",    BOND_AD_STABLE,    BOND_VALFLAG_DEFAULT},
-	{ "bandwidth", BOND_AD_BANDWIDTH, 0},
-	{ "count",     BOND_AD_COUNT,     0},
-	{ NULL,        -1,                0},
+	{ "stable",          BOND_AD_STABLE,    BOND_VALFLAG_DEFAULT},
+	{ "bandwidth",       BOND_AD_BANDWIDTH, 0},
+	{ "count",           BOND_AD_COUNT,     0},
+	{ "actor_port_prio", BOND_AD_PRIO,      0},
+	{ NULL,              -1,                0},
 };
 
 static const struct bond_opt_value bond_num_peer_notif_tbl[] = {

include/net/bond_3ad.h

···
 	BOND_AD_STABLE = 0,
 	BOND_AD_BANDWIDTH = 1,
 	BOND_AD_COUNT = 2,
+	BOND_AD_PRIO = 3,
 };
 
 /* rx machine states(43.4.11 in the 802.3ad standard) */