1 files changed, 31 insertions, 17 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 092b0551e77..56df440a950 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -51,6 +51,7 @@
 #include <linux/skbuff.h>	/* struct sk_buff */
 #include <linux/mm.h>
 #include <linux/security.h>
+#include <linux/slab.h>
 
 #include <linux/filter.h>
 #include <linux/rculist_nulls.h>
@@ -261,7 +262,7 @@ struct sock {
 #ifdef CONFIG_XFRM
 	struct xfrm_policy	*sk_policy[2];
 #endif
-	rwlock_t		sk_dst_lock;
+	spinlock_t		sk_dst_lock;
 	atomic_t		sk_rmem_alloc;
 	atomic_t		sk_wmem_alloc;
 	atomic_t		sk_omem_alloc;
@@ -1191,7 +1192,8 @@ extern unsigned long sock_i_ino(struct sock *sk);
 static inline struct dst_entry *
 __sk_dst_get(struct sock *sk)
 {
-	return sk->sk_dst_cache;
+	return rcu_dereference_check(sk->sk_dst_cache, rcu_read_lock_held() ||
+						       sock_owned_by_user(sk));
 }
 
 static inline struct dst_entry *
@@ -1199,50 +1201,62 @@ sk_dst_get(struct sock *sk)
 {
 	struct dst_entry *dst;
 
-	read_lock(&sk->sk_dst_lock);
-	dst = sk->sk_dst_cache;
+	rcu_read_lock();
+	dst = rcu_dereference(sk->sk_dst_cache);
 	if (dst)
 		dst_hold(dst);
-	read_unlock(&sk->sk_dst_lock);
+	rcu_read_unlock();
 	return dst;
 }
 
+extern void sk_reset_txq(struct sock *sk);
+
+static inline void dst_negative_advice(struct sock *sk)
+{
+	struct dst_entry *ndst, *dst = __sk_dst_get(sk);
+
+	if (dst && dst->ops->negative_advice) {
+		ndst = dst->ops->negative_advice(dst);
+
+		if (ndst != dst) {
+			rcu_assign_pointer(sk->sk_dst_cache, ndst);
+			sk_reset_txq(sk);
+		}
+	}
+}
+
 static inline void
 __sk_dst_set(struct sock *sk, struct dst_entry *dst)
 {
 	struct dst_entry *old_dst;
 
 	sk_tx_queue_clear(sk);
-	old_dst = sk->sk_dst_cache;
-	sk->sk_dst_cache = dst;
+	old_dst = rcu_dereference_check(sk->sk_dst_cache,
+					lockdep_is_held(&sk->sk_dst_lock));
+	rcu_assign_pointer(sk->sk_dst_cache, dst);
 	dst_release(old_dst);
 }
 
 static inline void
 sk_dst_set(struct sock *sk, struct dst_entry *dst)
 {
-	write_lock(&sk->sk_dst_lock);
+	spin_lock(&sk->sk_dst_lock);
 	__sk_dst_set(sk, dst);
-	write_unlock(&sk->sk_dst_lock);
+	spin_unlock(&sk->sk_dst_lock);
 }
 
 static inline void
 __sk_dst_reset(struct sock *sk)
 {
-	struct dst_entry *old_dst;
-
-	sk_tx_queue_clear(sk);
-	old_dst = sk->sk_dst_cache;
-	sk->sk_dst_cache = NULL;
-	dst_release(old_dst);
+	__sk_dst_set(sk, NULL);
 }
 
 static inline void
 sk_dst_reset(struct sock *sk)
 {
-	write_lock(&sk->sk_dst_lock);
+	spin_lock(&sk->sk_dst_lock);
 	__sk_dst_reset(sk);
-	write_unlock(&sk->sk_dst_lock);
+	spin_unlock(&sk->sk_dst_lock);
 }
 
 extern struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie);