From 237c7672dc1d0a2e2eb5e4d1208385592bbbfdf0 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <dada1@cosmosbay.com>
Date: Wed, 29 Oct 2008 11:19:58 -0700
Subject: [PATCH] --- yaml --- r: 121527 b: refs/heads/master c:
 96631ed16c514cf8b28fab991a076985ce378c26 h: refs/heads/master i:   121525:
 873d04c1ae9939850fe0a0efd6ec318c088270f1   121523:
 78c7a7c5b13ebd25bba3a09286f12179f3406c07   121519:
 16d6eced6ee37c87f7dc6de8ee33efe698959a67 v: v3

---
 [refs]                        |  2 +-
 trunk/include/linux/rculist.h | 17 +++++++++++++++++
 trunk/include/net/sock.h      |  4 ++--
 trunk/net/ipv4/udp.c          |  4 ++--
 trunk/net/ipv6/udp.c          |  4 ++--
 5 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/[refs] b/[refs]
index edfa13a80a76..bb2e684eb7f8 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f52b5054ec108aaa9e903850d6b62af8ae3fe6ae
+refs/heads/master: 96631ed16c514cf8b28fab991a076985ce378c26
diff --git a/trunk/include/linux/rculist.h b/trunk/include/linux/rculist.h
index e649bd3f2c97..3ba2998b22ba 100644
--- a/trunk/include/linux/rculist.h
+++ b/trunk/include/linux/rculist.h
@@ -383,5 +383,22 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
 		pos = rcu_dereference(pos->next))
 
+/**
+ * hlist_for_each_entry_rcu_safenext - iterate over rcu list of given type
+ * @tpos:	the type * to use as a loop cursor.
+ * @pos:	the &struct hlist_node to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the hlist_node within the struct.
+ * @next:       the &struct hlist_node to use as a next cursor
+ *
+ * Special version of hlist_for_each_entry_rcu that make sure
+ * each next pointer is fetched before each iteration.
+ */
+#define hlist_for_each_entry_rcu_safenext(tpos, pos, head, member, next) \
+	for (pos = rcu_dereference((head)->first);			 \
+		pos && ({ next = pos->next; smp_rmb(); prefetch(next); 1; }) &&	\
+		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
+		pos = rcu_dereference(next))
+
 #endif	/* __KERNEL__ */
 #endif
diff --git a/trunk/include/net/sock.h b/trunk/include/net/sock.h
index 0bea25db5471..a4f6d3fc0470 100644
--- a/trunk/include/net/sock.h
+++ b/trunk/include/net/sock.h
@@ -419,8 +419,8 @@ static __inline__ void sk_add_bind_node(struct sock *sk,
 
 #define sk_for_each(__sk, node, list) \
 	hlist_for_each_entry(__sk, node, list, sk_node)
-#define sk_for_each_rcu(__sk, node, list) \
-	hlist_for_each_entry_rcu(__sk, node, list, sk_node)
+#define sk_for_each_rcu_safenext(__sk, node, list, next) \
+	hlist_for_each_entry_rcu_safenext(__sk, node, list, sk_node, next)
 #define sk_for_each_from(__sk, node) \
 	if (__sk && ({ node = &(__sk)->sk_node; 1; })) \
 		hlist_for_each_entry_from(__sk, node, sk_node)
diff --git a/trunk/net/ipv4/udp.c b/trunk/net/ipv4/udp.c
index ced820318f94..c3ecec8a9e1c 100644
--- a/trunk/net/ipv4/udp.c
+++ b/trunk/net/ipv4/udp.c
@@ -256,7 +256,7 @@ static struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 		int dif, struct udp_table *udptable)
 {
 	struct sock *sk, *result;
-	struct hlist_node *node;
+	struct hlist_node *node, *next;
 	unsigned short hnum = ntohs(dport);
 	unsigned int hash = udp_hashfn(net, hnum);
 	struct udp_hslot *hslot = &udptable->hash[hash];
@@ -266,7 +266,7 @@ static struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 begin:
 	result = NULL;
 	badness = -1;
-	sk_for_each_rcu(sk, node, &hslot->head) {
+	sk_for_each_rcu_safenext(sk, node, &hslot->head, next) {
 		/*
 		 * lockless reader, and SLAB_DESTROY_BY_RCU items:
 		 * We must check this item was not moved to another chain
diff --git a/trunk/net/ipv6/udp.c b/trunk/net/ipv6/udp.c
index 1d9790e43dfc..32d914db6c4f 100644
--- a/trunk/net/ipv6/udp.c
+++ b/trunk/net/ipv6/udp.c
@@ -98,7 +98,7 @@ static struct sock *__udp6_lib_lookup(struct net *net,
 				      int dif, struct udp_table *udptable)
 {
 	struct sock *sk, *result;
-	struct hlist_node *node;
+	struct hlist_node *node, *next;
 	unsigned short hnum = ntohs(dport);
 	unsigned int hash = udp_hashfn(net, hnum);
 	struct udp_hslot *hslot = &udptable->hash[hash];
@@ -108,7 +108,7 @@ static struct sock *__udp6_lib_lookup(struct net *net,
 begin:
 	result = NULL;
 	badness = -1;
-	sk_for_each_rcu(sk, node, &hslot->head) {
+	sk_for_each_rcu_safenext(sk, node, &hslot->head, next) {
 		/*
 		 * lockless reader, and SLAB_DESTROY_BY_RCU items:
 		 * We must check this item was not moved to another chain