1 files changed, 24 insertions, 13 deletions

diff --git a/net/ipv6/tunnel6.c b/net/ipv6/tunnel6.c
index fc3c86a47452..4f3cec12aa85 100644
--- a/net/ipv6/tunnel6.c
+++ b/net/ipv6/tunnel6.c
@@ -30,28 +30,31 @@
 #include <net/protocol.h>
 #include <net/xfrm.h>
 
-static struct xfrm6_tunnel *tunnel6_handlers;
-static struct xfrm6_tunnel *tunnel46_handlers;
+static struct xfrm6_tunnel __rcu *tunnel6_handlers __read_mostly;
+static struct xfrm6_tunnel __rcu *tunnel46_handlers __read_mostly;
 static DEFINE_MUTEX(tunnel6_mutex);
 
 int xfrm6_tunnel_register(struct xfrm6_tunnel *handler, unsigned short family)
 {
-        struct xfrm6_tunnel **pprev;
+        struct xfrm6_tunnel __rcu **pprev;
+        struct xfrm6_tunnel *t;
         int ret = -EEXIST;
         int priority = handler->priority;
 
         mutex_lock(&tunnel6_mutex);
 
         for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
-             *pprev; pprev = &(*pprev)->next) {
-                if ((*pprev)->priority > priority)
+             (t = rcu_dereference_protected(*pprev,
+                        lockdep_is_held(&tunnel6_mutex))) != NULL;
+             pprev = &t->next) {
+                if (t->priority > priority)
                         break;
-                if ((*pprev)->priority == priority)
+                if (t->priority == priority)
                         goto err;
         }
 
         handler->next = *pprev;
-        *pprev = handler;
+        rcu_assign_pointer(*pprev, handler);
 
         ret = 0;
 
@@ -65,14 +68,17 @@ EXPORT_SYMBOL(xfrm6_tunnel_register);
 
 int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)
 {
-        struct xfrm6_tunnel **pprev;
+        struct xfrm6_tunnel __rcu **pprev;
+        struct xfrm6_tunnel *t;
         int ret = -ENOENT;
 
         mutex_lock(&tunnel6_mutex);
 
         for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
-             *pprev; pprev = &(*pprev)->next) {
-                if (*pprev == handler) {
+             (t = rcu_dereference_protected(*pprev,
+                        lockdep_is_held(&tunnel6_mutex))) != NULL;
+             pprev = &t->next) {
+                if (t == handler) {
                         *pprev = handler->next;
                         ret = 0;
                         break;
@@ -88,6 +94,11 @@ int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)
 
 EXPORT_SYMBOL(xfrm6_tunnel_deregister);
 
+#define for_each_tunnel_rcu(head, handler)              \
+        for (handler = rcu_dereference(head);           \
+             handler != NULL;                           \
+             handler = rcu_dereference(handler->next))  \
+
 static int tunnel6_rcv(struct sk_buff *skb)
 {
         struct xfrm6_tunnel *handler;
@@ -95,7 +106,7 @@ static int tunnel6_rcv(struct sk_buff *skb)
         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
                 goto drop;
 
-        for (handler = tunnel6_handlers; handler; handler = handler->next)
+        for_each_tunnel_rcu(tunnel6_handlers, handler)
                 if (!handler->handler(skb))
                         return 0;
 
@@ -113,7 +124,7 @@ static int tunnel46_rcv(struct sk_buff *skb)
         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
                 goto drop;
 
-        for (handler = tunnel46_handlers; handler; handler = handler->next)
+        for_each_tunnel_rcu(tunnel46_handlers, handler)
                 if (!handler->handler(skb))
                         return 0;
 
@@ -129,7 +140,7 @@ static void tunnel6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 {
         struct xfrm6_tunnel *handler;
 
-        for (handler = tunnel6_handlers; handler; handler = handler->next)
+        for_each_tunnel_rcu(tunnel6_handlers, handler)
                 if (!handler->err_handler(skb, opt, type, code, offset, info))
                         break;
 }