Merge branch 'socket-option-lockless'

Eric Dumazet says:

====================
net: more data-races fixes and lockless socket options

This is yet another round of data-races fixes,
and lockless socket options.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 7 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 2800d587b08d..01f0005cb7d8 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2007,21 +2007,33 @@ static inline void sk_tx_queue_set(struct sock *sk, int tx_queue)
 	/* sk_tx_queue_mapping accept only upto a 16-bit value */
 	if (WARN_ON_ONCE((unsigned short)tx_queue >= USHRT_MAX))
 		return;
-	sk->sk_tx_queue_mapping = tx_queue;
+	/* Paired with READ_ONCE() in sk_tx_queue_get() and
+	 * other WRITE_ONCE() because socket lock might be not held.
+	 */
+	WRITE_ONCE(sk->sk_tx_queue_mapping, tx_queue);
 }
 
 #define NO_QUEUE_MAPPING	USHRT_MAX
 
 static inline void sk_tx_queue_clear(struct sock *sk)
 {
-	sk->sk_tx_queue_mapping = NO_QUEUE_MAPPING;
+	/* Paired with READ_ONCE() in sk_tx_queue_get() and
+	 * other WRITE_ONCE() because socket lock might be not held.
+	 */
+	WRITE_ONCE(sk->sk_tx_queue_mapping, NO_QUEUE_MAPPING);
 }
 
 static inline int sk_tx_queue_get(const struct sock *sk)
 {
-	if (sk && sk->sk_tx_queue_mapping != NO_QUEUE_MAPPING)
-		return sk->sk_tx_queue_mapping;
+	if (sk) {
+		/* Paired with WRITE_ONCE() in sk_tx_queue_clear()
+		 * and sk_tx_queue_set().
+		 */
+		int val = READ_ONCE(sk->sk_tx_queue_mapping);
 
+		if (val != NO_QUEUE_MAPPING)
+			return val;
+	}
 	return -1;
 }
 
@@ -2170,7 +2182,7 @@ 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);
 		}
 	}
 }
@@ -2187,7 +2199,7 @@ __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);
@@ -2200,7 +2212,7 @@ 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);
 }