[PATCHv2 net-next 2/3] bonding: support aggregator selection based on port priority

[Hangbin Liu <liuhangbin@gmail.com>]

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 <liuhangbin@gmail.com>
---
 Documentation/networking/bonding.rst |  9 ++++++++-
 drivers/net/bonding/bond_3ad.c       | 27 +++++++++++++++++++++++++++
 drivers/net/bonding/bond_options.c   |  1 +
 include/net/bond_3ad.h               |  1 +
 4 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/bonding.rst b/Documentation/networking/bonding.rst
index 874d8a4681ec..151c964562db 100644
--- a/Documentation/networking/bonding.rst
+++ b/Documentation/networking/bonding.rst
@@ -250,7 +250,14 @@ ad_select
 		ports (slaves).  Reselection occurs as described under the
 		"bandwidth" setting, above.
 
-	The bandwidth and count selection policies permit failover of
+	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 ad_actor_port_prio, not per port prio, which is
+		used for primary reselect.
+
+	The bandwidth, count and 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 or in number of ports) active at all times.
diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 19b389b81600..dcc1a1750df5 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -747,6 +747,18 @@ static int __agg_active_ports(struct aggregator *agg)
 	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
@@ -1707,6 +1719,9 @@ static struct aggregator *ad_agg_selection_test(struct aggregator *best,
 	 * BOND_AD_COUNT: Select by count of ports.  If count is equal,
 	 *     select by bandwidth.
 	 *
+	 * BOND_AD_PRIO: Select by total priority of ports. If priority
+	 *     is equal, select by count.
+	 *
 	 * BOND_AD_STABLE, BOND_AD_BANDWIDTH: Select by bandwidth.
 	 */
 	if (!best)
@@ -1725,6 +1740,14 @@ static struct aggregator *ad_agg_selection_test(struct aggregator *best,
 		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;
@@ -1790,6 +1813,10 @@ static int agg_device_up(const struct aggregator *agg)
  * (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.
+ *
  * FIXME: this function MUST be called with the first agg in the bond, or
  * __get_active_agg() won't work correctly. This function should be better
  * called with the bond itself, and retrieve the first agg from it.
diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index 5b58326dd24c..4bfff38b9ad0 100644
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -165,6 +165,7 @@ 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},
+	{ "prio",      BOND_AD_PRIO,      0},
 	{ NULL,        -1,                0},
 };
 
diff --git a/include/net/bond_3ad.h b/include/net/bond_3ad.h
index bf551ca70359..34495df965f0 100644
--- a/include/net/bond_3ad.h
+++ b/include/net/bond_3ad.h
@@ -26,6 +26,7 @@ enum {
 	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) */
-- 
2.50.1