netdev - [PATCH net-next 10/10] net: annotate a data-race in __dev_xmit

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Message-ID: <20251110094505.3335073-11-edumazet@google.com>
Date: Mon, 10 Nov 2025 09:45:05 +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: Simon Horman <horms@...nel.org>, Jamal Hadi Salim <jhs@...atatu.com>, 
	Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, 
	"Toke Høiland-Jørgensen" <toke@...hat.com>, Kuniyuki Iwashima <kuniyu@...gle.com>, 
	Willem de Bruijn <willemb@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 10/10] net: annotate a data-race in __dev_xmit_skb()

q->limit is read locklessly, add a READ_ONCE().

Fixes: 100dfa74cad9 ("net: dev_queue_xmit() llist adoption")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 44022fdec655e40e70ff5e1894f55fc76235b00c..ac994974e2a81889fcc0a2e664edcdb7cfd0496d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4194,7 +4194,7 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
 	do {
 		if (first_n && !defer_count) {
 			defer_count = atomic_long_inc_return(&q->defer_count);
-			if (unlikely(defer_count > q->limit)) {
+			if (unlikely(defer_count > READ_ONCE(q->limit))) {
 				kfree_skb_reason(skb, SKB_DROP_REASON_QDISC_DROP);
 				return NET_XMIT_DROP;
 			}
-- 
2.51.2.1041.gc1ab5b90ca-goog