bonding: annotate data-races arcound churn variables

These fields are updated asynchronously by the bonding state machine
in ad_churn_machine() while holding bond->mode_lock.

bond_info_show_slave() and bond_fill_slave_info() read them without
bond->mode_lock being held, we need to add READ_ONCE() and
WRITE_ONCE() annotations.

Note that AD_CHURN_MONITOR, AD_CHURN, and AD_NO_CHURN are defined
exclusively in (kernel private) include/net/bond_3ad.h header.

They should be moved to include/uapi/linux/if_bonding.h or userspace
tools will have to hardcode their values.

Fixes: 4916f2e2f3fc ("bonding: print churn state via netlink")
Fixes: 14c9551a32eb ("bonding: Implement port churn-machine (AD standard 43.4.17).")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260603123514.388226-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 16 insertions, 14 deletions

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index f0aa7d2f2171..985ef66dc333 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -1386,8 +1386,8 @@ static void ad_churn_machine(struct port *port)
 {
 	if (port->sm_vars & AD_PORT_CHURNED) {
 		port->sm_vars &= ~AD_PORT_CHURNED;
-		port->sm_churn_actor_state = AD_CHURN_MONITOR;
-		port->sm_churn_partner_state = AD_CHURN_MONITOR;
+		WRITE_ONCE(port->sm_churn_actor_state, AD_CHURN_MONITOR);
+		WRITE_ONCE(port->sm_churn_partner_state, AD_CHURN_MONITOR);
 		port->sm_churn_actor_timer_counter =
 			__ad_timer_to_ticks(AD_ACTOR_CHURN_TIMER, 0);
 		port->sm_churn_partner_timer_counter =
@@ -1398,20 +1398,22 @@ static void ad_churn_machine(struct port *port)
 	    !(--port->sm_churn_actor_timer_counter) &&
 	    port->sm_churn_actor_state == AD_CHURN_MONITOR) {
 		if (port->actor_oper_port_state & LACP_STATE_SYNCHRONIZATION) {
-			port->sm_churn_actor_state = AD_NO_CHURN;
+			WRITE_ONCE(port->sm_churn_actor_state, AD_NO_CHURN);
 		} else {
-			port->churn_actor_count++;
-			port->sm_churn_actor_state = AD_CHURN;
+			WRITE_ONCE(port->churn_actor_count,
+				   port->churn_actor_count + 1);
+			WRITE_ONCE(port->sm_churn_actor_state, AD_CHURN);
 		}
 	}
 	if (port->sm_churn_partner_timer_counter &&
 	    !(--port->sm_churn_partner_timer_counter) &&
 	    port->sm_churn_partner_state == AD_CHURN_MONITOR) {
 		if (port->partner_oper.port_state & LACP_STATE_SYNCHRONIZATION) {
-			port->sm_churn_partner_state = AD_NO_CHURN;
+			WRITE_ONCE(port->sm_churn_partner_state, AD_NO_CHURN);
 		} else {
-			port->churn_partner_count++;
-			port->sm_churn_partner_state = AD_CHURN;
+			WRITE_ONCE(port->churn_partner_count,
+				   port->churn_partner_count + 1);
+			WRITE_ONCE(port->sm_churn_partner_state, AD_CHURN);
 		}
 	}
 }
diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
index c7d3e0602c83..90365d3f7ebf 100644
--- a/drivers/net/bonding/bond_netlink.c
+++ b/drivers/net/bonding/bond_netlink.c
@@ -82,10 +82,10 @@ static int bond_fill_slave_info(struct sk_buff *skb,
 				goto nla_put_failure_rcu;
 
 			if (nla_put_u8(skb, IFLA_BOND_SLAVE_AD_CHURN_ACTOR_STATE,
-				       ad_port->sm_churn_actor_state))
+				       READ_ONCE(ad_port->sm_churn_actor_state)))
 				goto nla_put_failure_rcu;
 			if (nla_put_u8(skb, IFLA_BOND_SLAVE_AD_CHURN_PARTNER_STATE,
-				       ad_port->sm_churn_partner_state))
+				       READ_ONCE(ad_port->sm_churn_partner_state)))
 				goto nla_put_failure_rcu;
 		}
 		rcu_read_unlock();
diff --git a/drivers/net/bonding/bond_procfs.c b/drivers/net/bonding/bond_procfs.c
index 3714aab1a3d9..3607b62f9b63 100644
--- a/drivers/net/bonding/bond_procfs.c
+++ b/drivers/net/bonding/bond_procfs.c
@@ -221,13 +221,13 @@ static void bond_info_show_slave(struct seq_file *seq,
 			seq_printf(seq, "Aggregator ID: %d\n",
 				   agg->aggregator_identifier);
 			seq_printf(seq, "Actor Churn State: %s\n",
-				   bond_3ad_churn_desc(port->sm_churn_actor_state));
+				   bond_3ad_churn_desc(READ_ONCE(port->sm_churn_actor_state)));
 			seq_printf(seq, "Partner Churn State: %s\n",
-				   bond_3ad_churn_desc(port->sm_churn_partner_state));
+				   bond_3ad_churn_desc(READ_ONCE(port->sm_churn_partner_state)));
 			seq_printf(seq, "Actor Churned Count: %d\n",
-				   port->churn_actor_count);
+				   READ_ONCE(port->churn_actor_count));
 			seq_printf(seq, "Partner Churned Count: %d\n",
-				   port->churn_partner_count);
+				   READ_ONCE(port->churn_partner_count));
 
 			if (capable(CAP_NET_ADMIN)) {
 				seq_puts(seq, "details actor lacp pdu:\n");