netdev - [PATCH net-next 3/3] bonding: no longer use RTNL in bonding_show_queue

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Message-ID: <20240408190437.2214473-4-edumazet@google.com>
Date: Mon,  8 Apr 2024 19:04:37 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Jay Vosburgh <j.vosburgh@...il.com>, Andy Gospodarek <andy@...yhouse.net>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 3/3] bonding: no longer use RTNL in bonding_show_queue_id()

Annotate lockless reads of slave->queue_id.

Annotate writes of slave->queue_id.

Switch bonding_show_queue_id() to rcu_read_lock()
and bond_for_each_slave_rcu().

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 drivers/net/bonding/bond_main.c        |  2 +-
 drivers/net/bonding/bond_netlink.c     |  3 ++-
 drivers/net/bonding/bond_options.c     |  2 +-
 drivers/net/bonding/bond_procfs.c      |  2 +-
 drivers/net/bonding/bond_sysfs.c       | 10 +++++-----
 drivers/net/bonding/bond_sysfs_slave.c |  2 +-
 6 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 08e9bdbf450afdc103931249259c58a08665dc02..b3a7d60c3a5ca60be1d9eed184ec1dad593a182b 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -5245,7 +5245,7 @@ static inline int bond_slave_override(struct bonding *bond,
 
 	/* Find out if any slaves have the same mapping as this skb. */
 	bond_for_each_slave_rcu(bond, slave, iter) {
-		if (slave->queue_id == skb_get_queue_mapping(skb)) {
+		if (READ_ONCE(slave->queue_id) == skb_get_queue_mapping(skb)) {
 			if (bond_slave_is_up(slave) &&
 			    slave->link == BOND_LINK_UP) {
 				bond_dev_queue_xmit(bond, skb, slave->dev);
diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
index 29b4c3d1b9b6ff873fe067e80bedf7cb681d18f1..2a6a424806aa603ad8a00ca797e9e22d38bd0435 100644
--- a/drivers/net/bonding/bond_netlink.c
+++ b/drivers/net/bonding/bond_netlink.c
@@ -51,7 +51,8 @@ static int bond_fill_slave_info(struct sk_buff *skb,
 		    slave_dev->addr_len, slave->perm_hwaddr))
 		goto nla_put_failure;
 
-	if (nla_put_u16(skb, IFLA_BOND_SLAVE_QUEUE_ID, slave->queue_id))
+	if (nla_put_u16(skb, IFLA_BOND_SLAVE_QUEUE_ID,
+			READ_ONCE(slave->queue_id)))
 		goto nla_put_failure;
 
 	if (nla_put_s32(skb, IFLA_BOND_SLAVE_PRIO, slave->prio))
diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index 4cdbc7e084f4b4cb3b150656aa765531806d8ad9..0cacd7027e352dbf3204d82b7ce1672469a186de 100644
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -1589,7 +1589,7 @@ static int bond_option_queue_id_set(struct bonding *bond,
 		goto err_no_cmd;
 
 	/* Actually set the qids for the slave */
-	update_slave->queue_id = qid;
+	WRITE_ONCE(update_slave->queue_id, qid);
 
 out:
 	return ret;
diff --git a/drivers/net/bonding/bond_procfs.c b/drivers/net/bonding/bond_procfs.c
index 43be458422b3f9448d96383b0fb140837562f446..7edf72ec816abd8b66917bdecd2c93d237629ffa 100644
--- a/drivers/net/bonding/bond_procfs.c
+++ b/drivers/net/bonding/bond_procfs.c
@@ -209,7 +209,7 @@ static void bond_info_show_slave(struct seq_file *seq,
 
 	seq_printf(seq, "Permanent HW addr: %*phC\n",
 		   slave->dev->addr_len, slave->perm_hwaddr);
-	seq_printf(seq, "Slave queue ID: %d\n", slave->queue_id);
+	seq_printf(seq, "Slave queue ID: %d\n", READ_ONCE(slave->queue_id));
 
 	if (BOND_MODE(bond) == BOND_MODE_8023AD) {
 		const struct port *port = &SLAVE_AD_INFO(slave)->port;
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 75ee7ca369034ef6fa58fc9399b566dd7044fedc..1e13bb17051567e2b5d9451ceef47f2cf1a588ec 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -625,10 +625,9 @@ static ssize_t bonding_show_queue_id(struct device *d,
 	struct slave *slave;
 	int res = 0;
 
-	if (!rtnl_trylock())
-		return restart_syscall();
+	rcu_read_lock();
 
-	bond_for_each_slave(bond, slave, iter) {
+	bond_for_each_slave_rcu(bond, slave, iter) {
 		if (res > (PAGE_SIZE - IFNAMSIZ - 6)) {
 			/* not enough space for another interface_name:queue_id pair */
 			if ((PAGE_SIZE - res) > 10)
@@ -637,12 +636,13 @@ static ssize_t bonding_show_queue_id(struct device *d,
 			break;
 		}
 		res += sysfs_emit_at(buf, res, "%s:%d ",
-				     slave->dev->name, slave->queue_id);
+				     slave->dev->name,
+				     READ_ONCE(slave->queue_id));
 	}
 	if (res)
 		buf[res-1] = '\n'; /* eat the leftover space */
 
-	rtnl_unlock();
+	rcu_read_unlock();
 
 	return res;
 }
diff --git a/drivers/net/bonding/bond_sysfs_slave.c b/drivers/net/bonding/bond_sysfs_slave.c
index 313866f2c0e49ac96299ffea307b1613955713ec..36d0e8440b5b94464b3226ce1a04f32361de5aa6 100644
--- a/drivers/net/bonding/bond_sysfs_slave.c
+++ b/drivers/net/bonding/bond_sysfs_slave.c
@@ -53,7 +53,7 @@ static SLAVE_ATTR_RO(perm_hwaddr);
 
 static ssize_t queue_id_show(struct slave *slave, char *buf)
 {
-	return sysfs_emit(buf, "%d\n", slave->queue_id);
+	return sysfs_emit(buf, "%d\n", READ_ONCE(slave->queue_id));
 }
 static SLAVE_ATTR_RO(queue_id);
 
-- 
2.44.0.478.gd926399ef9-goog