netdev - [PATCH net-next 3/8] rtnetlink: do not depend on RTNL for IFLA

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Message-ID: <20240503192059.3884225-4-edumazet@google.com>
Date: Fri,  3 May 2024 19:20:54 +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: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 3/8] rtnetlink: do not depend on RTNL for IFLA_TXQLEN output

rtnl_fill_ifinfo() can read dev->tx_queue_len locklessly,
granted we add corresponding READ_ONCE()/WRITE_ONCE() annotations.

Add missing READ_ONCE(dev->tx_queue_len) in teql_enqueue()

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/dev.c       | 4 ++--
 net/core/rtnetlink.c | 2 +-
 net/sched/sch_api.c  | 2 +-
 net/sched/sch_teql.c | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index e02d2363347e2e403ccb2a59d44d35cee9a1b367..9c8c2ab2d76c3587d9114bc86a395341e1fd4d2b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8959,7 +8959,7 @@ int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)
 		return -ERANGE;
 
 	if (new_len != orig_len) {
-		dev->tx_queue_len = new_len;
+		WRITE_ONCE(dev->tx_queue_len, new_len);
 		res = call_netdevice_notifiers(NETDEV_CHANGE_TX_QUEUE_LEN, dev);
 		res = notifier_to_errno(res);
 		if (res)
@@ -8973,7 +8973,7 @@ int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)
 
 err_rollback:
 	netdev_err(dev, "refused to change device tx_queue_len\n");
-	dev->tx_queue_len = orig_len;
+	WRITE_ONCE(dev->tx_queue_len, orig_len);
 	return res;
 }
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a92e3b533d8d2ed1a52a40e02eb994c3070ede38..77d14528bdefc8b655f5da37ed88d0b937f35a61 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1837,7 +1837,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
 	if (nla_put_string(skb, IFLA_IFNAME, devname))
 		goto nla_put_failure;
 
-	if (nla_put_u32(skb, IFLA_TXQLEN, dev->tx_queue_len) ||
+	if (nla_put_u32(skb, IFLA_TXQLEN, READ_ONCE(dev->tx_queue_len)) ||
 	    nla_put_u8(skb, IFLA_OPERSTATE,
 		       netif_running(dev) ? dev->operstate : IF_OPER_DOWN) ||
 	    nla_put_u8(skb, IFLA_LINKMODE, dev->link_mode) ||
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 6292d6d73b720fef6766d08ed01d8b93a99f97b6..74afc210527d237cca3b48166be5918f802eb326 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1334,7 +1334,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 	 * before again attaching a qdisc.
 	 */
 	if ((dev->priv_flags & IFF_NO_QUEUE) && (dev->tx_queue_len == 0)) {
-		dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
+		WRITE_ONCE(dev->tx_queue_len, DEFAULT_TX_QUEUE_LEN);
 		netdev_info(dev, "Caught tx_queue_len zero misconfig\n");
 	}
 
diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index 59304611dc0050e525de5f45b2a3b8628b684ff3..29850d0f073308290ac1a479bc98315034990663 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -78,7 +78,7 @@ teql_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
 	struct net_device *dev = qdisc_dev(sch);
 	struct teql_sched_data *q = qdisc_priv(sch);
 
-	if (q->q.qlen < dev->tx_queue_len) {
+	if (q->q.qlen < READ_ONCE(dev->tx_queue_len)) {
 		__skb_queue_tail(&q->q, skb);
 		return NET_XMIT_SUCCESS;
 	}
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog