[PATCH net] net: bonding: annotate lockless writes with WRITE_ONCE()

[Eric Dumazet <edumazet@google.com>]

Several fields in bonding are read locklessly using READ_ONCE()
(or ACCESS_ONCE() previously) but have corresponding writes that
do not use WRITE_ONCE().

Add WRITE_ONCE() annotations to:
- bond->send_peer_notif decrements in bond_peer_notify_may_events()
  and reset in bond_close().
- bond->slave_cnt increments and decrements in bond_enslave() and
  __bond_release_one().
- bond->recv_probe updates in bond_open(), bond_option_arp_interval_set()
  and rlb_initialize().
- slaves->count decrement in bond_skip_slave().

Fixes: 4d97480b1806 ("bonding: use local function pointer of bond->recv_probe in bond_handle_frame")
Fixes: 9a72c2da690d ("bonding: fix div by zero while enslaving and transmitting")
Fixes: ee6377147409 ("bonding: Simplify the xmit function for modes that use xmit_hash")
Fixes: 429208aab9db ("net: bonding: add the READ_ONCE/WRITE_ONCE for outside lock accessing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jay Vosburgh <jv@jvosburgh.net>
---
 drivers/net/bonding/bond_alb.c     |  2 +-
 drivers/net/bonding/bond_main.c    | 14 +++++++-------
 drivers/net/bonding/bond_options.c |  4 ++--
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 839f7482dc1823b12a13437a4b6639e3b63d46ec..d2fb67a47cf99651423602c39a3c89a5f5379913 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -875,7 +875,7 @@ static int rlb_initialize(struct bonding *bond)
 	spin_unlock_bh(&bond->mode_lock);
 
 	/* register to receive ARPs */
-	bond->recv_probe = rlb_arp_recv;
+	WRITE_ONCE(bond->recv_probe, rlb_arp_recv);
 
 	return 0;
 }
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index ef9eb0c53c661fddc48bea03f8091f239dd0f3e8..947d92a669b676524ce7a3786bc8acbc8d36fb3c 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1245,7 +1245,7 @@ static void bond_peer_notify_may_events(struct bonding *bond, bool force)
 	}
 
 	if (notified || force)
-		bond->send_peer_notif--;
+		WRITE_ONCE(bond->send_peer_notif, bond->send_peer_notif - 1);
 }
 
 /**
@@ -2284,7 +2284,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 		}
 	}
 
-	bond->slave_cnt++;
+	WRITE_ONCE(bond->slave_cnt, bond->slave_cnt + 1);
 	netdev_compute_master_upper_features(bond->dev, true);
 	bond_set_carrier(bond);
 
@@ -2533,7 +2533,7 @@ static int __bond_release_one(struct net_device *bond_dev,
 
 	unblock_netpoll_tx();
 	synchronize_rcu();
-	bond->slave_cnt--;
+	WRITE_ONCE(bond->slave_cnt, bond->slave_cnt - 1);
 
 	if (!bond_has_slaves(bond)) {
 		call_netdevice_notifiers(NETDEV_CHANGEADDR, bond->dev);
@@ -4385,13 +4385,13 @@ static int bond_open(struct net_device *bond_dev)
 
 	if (bond->params.arp_interval) {  /* arp interval, in milliseconds. */
 		queue_delayed_work(bond->wq, &bond->arp_work, 0);
-		bond->recv_probe = bond_rcv_validate;
+		WRITE_ONCE(bond->recv_probe, bond_rcv_validate);
 	}
 
 	if (BOND_MODE(bond) == BOND_MODE_8023AD) {
 		queue_delayed_work(bond->wq, &bond->ad_work, 0);
 		/* register to receive LACPDUs */
-		bond->recv_probe = bond_3ad_lacpdu_recv;
+		WRITE_ONCE(bond->recv_probe, bond_3ad_lacpdu_recv);
 		bond_3ad_initiate_agg_selection(bond, 1);
 
 		bond_for_each_slave(bond, slave, iter)
@@ -4413,7 +4413,7 @@ static int bond_close(struct net_device *bond_dev)
 	struct slave *slave;
 
 	bond_work_cancel_all(bond);
-	bond->send_peer_notif = 0;
+	WRITE_ONCE(bond->send_peer_notif, 0);
 	WRITE_ONCE(bond->recv_probe, NULL);
 
 	/* Wait for any in-flight RX handlers */
@@ -5118,7 +5118,7 @@ static void bond_skip_slave(struct bond_up_slave *slaves,
 		if (skipslave == slaves->arr[idx]) {
 			slaves->arr[idx] =
 				slaves->arr[slaves->count - 1];
-			slaves->count--;
+			WRITE_ONCE(slaves->count, slaves->count - 1);
 			break;
 		}
 	}
diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index 36b8d89387ee5d67a51087fa2c6edd0de579ab3f..9efadeff6a2238960828a0604e304108ad9c2dc7 100644
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -1147,11 +1147,11 @@ static int bond_option_arp_interval_set(struct bonding *bond,
 		 */
 		if (!newval->value) {
 			if (bond->params.arp_validate)
-				bond->recv_probe = NULL;
+				WRITE_ONCE(bond->recv_probe, NULL);
 			cancel_delayed_work_sync(&bond->arp_work);
 		} else {
 			/* arp_validate can be set only in active-backup mode */
-			bond->recv_probe = bond_rcv_validate;
+			WRITE_ONCE(bond->recv_probe, bond_rcv_validate);
 			cancel_delayed_work_sync(&bond->mii_work);
 			queue_delayed_work(bond->wq, &bond->arp_work, 0);
 		}
-- 
2.55.0.897.gb25b4bd76c-goog