[PATCH AUTOSEL 6.1 09/18] net: annotate data-races around sk->sk_dst_pending_confirm

[Sasha Levin]

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit eb44ad4e635132754bfbcb18103f1dcb7058aedd ]

This field can be read or written without socket lock being held.

Add annotations to avoid load-store tearing.

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/net/sock.h    | 6 +++---
 net/core/sock.c       | 2 +-
 net/ipv4/tcp_output.c | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 8d98fcd9e89a9..b6027b01c2455 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2207,7 +2207,7 @@ static inline void __dst_negative_advice(struct sock *sk)
 		if (ndst != dst) {
 			rcu_assign_pointer(sk->sk_dst_cache, ndst);
 			sk_tx_queue_clear(sk);
-			sk->sk_dst_pending_confirm = 0;
+			WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 		}
 	}
 }
@@ -2224,7 +2224,7 @@ __sk_dst_set(struct sock *sk, struct dst_entry *dst)
 	struct dst_entry *old_dst;
 
 	sk_tx_queue_clear(sk);
-	sk->sk_dst_pending_confirm = 0;
+	WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 	old_dst = rcu_dereference_protected(sk->sk_dst_cache,
 					    lockdep_sock_is_held(sk));
 	rcu_assign_pointer(sk->sk_dst_cache, dst);
@@ -2237,7 +2237,7 @@ sk_dst_set(struct sock *sk, struct dst_entry *dst)
 	struct dst_entry *old_dst;
 
 	sk_tx_queue_clear(sk);
-	sk->sk_dst_pending_confirm = 0;
+	WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 	old_dst = xchg((__force struct dst_entry **)&sk->sk_dst_cache, dst);
 	dst_release(old_dst);
 }
diff --git a/net/core/sock.c b/net/core/sock.c
index 0ee2e33bbe5f8..4305e55dbfba4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -596,7 +596,7 @@ struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie)
 	    INDIRECT_CALL_INET(dst->ops->check, ip6_dst_check, ipv4_dst_check,
 			       dst, cookie) == NULL) {
 		sk_tx_queue_clear(sk);
-		sk->sk_dst_pending_confirm = 0;
+		WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 		RCU_INIT_POINTER(sk->sk_dst_cache, NULL);
 		dst_release(dst);
 		return NULL;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index cc7ed86fb0a57..5b93d1ed1ed19 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1319,7 +1319,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 	skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree;
 	refcount_add(skb->truesize, &sk->sk_wmem_alloc);
 
-	skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm);
+	skb_set_dst_pending_confirm(skb, READ_ONCE(sk->sk_dst_pending_confirm));
 
 	/* Build TCP header and checksum it. */
 	th = (struct tcphdr *)skb->data;
-- 
2.42.0