packet: convert socket list to RCU (v3)

Convert AF_PACKET to use RCU, eliminating one more reader/writer lock.

There is no need for a real sk_del_node_init_rcu(), because sk_del_node_init
is doing the equivalent thing to hlst_del_init_rcu already; but added
some comments to try and make that obvious.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 12 insertions, 2 deletions

diff --git a/include/net/netns/packet.h b/include/net/netns/packet.h
index 637daf698884..cb4e894c0f8d 100644
--- a/include/net/netns/packet.h
+++ b/include/net/netns/packet.h
@@ -4,11 +4,11 @@
 #ifndef __NETNS_PACKET_H__
 #define __NETNS_PACKET_H__
 
-#include <linux/list.h>
+#include <linux/rculist.h>
 #include <linux/spinlock.h>
 
 struct netns_packet {
-        rwlock_t                sklist_lock;
+        spinlock_t              sklist_lock;
         struct hlist_head       sklist;
 };
 
diff --git a/include/net/sock.h b/include/net/sock.h
index 580d51fa28e9..6cb1676e409a 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -381,6 +381,7 @@ static __inline__ void __sk_del_node(struct sock *sk)
         __hlist_del(&sk->sk_node);
 }
 
+/* NB: equivalent to hlist_del_init_rcu */
 static __inline__ int __sk_del_node_init(struct sock *sk)
 {
         if (sk_hashed(sk)) {
@@ -421,6 +422,7 @@ static __inline__ int sk_del_node_init(struct sock *sk)
         }
         return rc;
 }
+#define sk_del_node_init_rcu(sk)        sk_del_node_init(sk)
 
 static __inline__ int __sk_nulls_del_node_init_rcu(struct sock *sk)
 {
@@ -454,6 +456,12 @@ static __inline__ void sk_add_node(struct sock *sk, struct hlist_head *list)
         __sk_add_node(sk, list);
 }
 
+static __inline__ void sk_add_node_rcu(struct sock *sk, struct hlist_head *list)
+{
+        sock_hold(sk);
+        hlist_add_head_rcu(&sk->sk_node, list);
+}
+
 static __inline__ void __sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)
 {
         hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list);
@@ -478,6 +486,8 @@ 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_nulls_for_each(__sk, node, list) \
         hlist_nulls_for_each_entry(__sk, node, list, sk_nulls_node)
 #define sk_nulls_for_each_rcu(__sk, node, list) \