mpls: Cleanup the rcu usage in the code.

Sparse was generating a lot of warnings mostly from missing annotations
in the code.  Add missing annotations and in a few cases tweak the code
for performance by moving work before loops.

This also fixes a problematic ommision of rcu_assign_pointer and
rcu_dereference.

Hopefully with complete rcu annotations any new rcu errors will stick
out like a sore thumb.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 59cc325..0f2833e 100644 (file)
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -24,7 +24,7 @@
 #define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, sizeof(unsigned long)))
 
 struct mpls_route { /* next hop label forwarding entry */
-       struct net_device       *rt_dev;
+       struct net_device __rcu *rt_dev;
        struct rcu_head         rt_rcu;
        u32                     rt_label[MAX_NEW_LABELS];
        u8                      rt_protocol; /* routing protocol that set this entry */
@@ -152,7 +152,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
                goto drop;
 
        /* Find the output device */
-       out_dev = rt->rt_dev;
+       out_dev = rcu_dereference(rt->rt_dev);
        if (!mpls_output_possible(out_dev))
                goto drop;
 
@@ -269,13 +269,15 @@ static void mpls_route_update(struct net *net, unsigned index,
                              struct net_device *dev, struct mpls_route *new,
                              const struct nl_info *info)
 {
+       struct mpls_route __rcu **platform_label;
        struct mpls_route *rt, *old = NULL;
 
        ASSERT_RTNL();
 
-       rt = net->mpls.platform_label[index];
-       if (!dev || (rt && (rt->rt_dev == dev))) {
-               rcu_assign_pointer(net->mpls.platform_label[index], new);
+       platform_label = rtnl_dereference(net->mpls.platform_label);
+       rt = rtnl_dereference(platform_label[index]);
+       if (!dev || (rt && (rtnl_dereference(rt->rt_dev) == dev))) {
+               rcu_assign_pointer(platform_label[index], new);
                old = rt;
        }
 
@@ -287,9 +289,14 @@ static void mpls_route_update(struct net *net, unsigned index,
 
 static unsigned find_free_label(struct net *net)
 {
+       struct mpls_route __rcu **platform_label;
+       size_t platform_labels;
        unsigned index;
-       for (index = 16; index < net->mpls.platform_labels; index++) {
-               if (!net->mpls.platform_label[index])
+
+       platform_label = rtnl_dereference(net->mpls.platform_label);
+       platform_labels = net->mpls.platform_labels;
+       for (index = 16; index < platform_labels; index++) {
+               if (!rtnl_dereference(platform_label[index]))
                        return index;
        }
        return LABEL_NOT_SPECIFIED;
@@ -297,6 +304,7 @@ static unsigned find_free_label(struct net *net)
 
 static int mpls_route_add(struct mpls_route_config *cfg)
 {
+       struct mpls_route __rcu **platform_label;
        struct net *net = cfg->rc_nlinfo.nl_net;
        struct net_device *dev = NULL;
        struct mpls_route *rt, *old;
@@ -345,7 +353,8 @@ static int mpls_route_add(struct mpls_route_config *cfg)
                goto errout;
 
        err = -EEXIST;
-       old = net->mpls.platform_label[index];
+       platform_label = rtnl_dereference(net->mpls.platform_label);
+       old = rtnl_dereference(platform_label[index]);
        if ((cfg->rc_nlflags & NLM_F_EXCL) && old)
                goto errout;
 
@@ -366,7 +375,7 @@ static int mpls_route_add(struct mpls_route_config *cfg)
        for (i = 0; i < rt->rt_labels; i++)
                rt->rt_label[i] = cfg->rc_output_label[i];
        rt->rt_protocol = cfg->rc_protocol;
-       rt->rt_dev = dev;
+       RCU_INIT_POINTER(rt->rt_dev, dev);
        rt->rt_via_family = cfg->rc_via_family;
        memcpy(rt->rt_via, cfg->rc_via, cfg->rc_via_alen);
 
@@ -406,14 +415,16 @@ errout:
 
 static void mpls_ifdown(struct net_device *dev)
 {
+       struct mpls_route __rcu **platform_label;
        struct net *net = dev_net(dev);
        unsigned index;
 
+       platform_label = rtnl_dereference(net->mpls.platform_label);
        for (index = 0; index < net->mpls.platform_labels; index++) {
-               struct mpls_route *rt = net->mpls.platform_label[index];
+               struct mpls_route *rt = rtnl_dereference(platform_label[index]);
                if (!rt)
                        continue;
-               if (rt->rt_dev != dev)
+               if (rtnl_dereference(rt->rt_dev) != dev)
                        continue;
                rt->rt_dev = NULL;
        }
@@ -653,6 +664,7 @@ static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh)
 static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
                           u32 label, struct mpls_route *rt, int flags)
 {
+       struct net_device *dev;
        struct nlmsghdr *nlh;
        struct rtmsg *rtm;
 
@@ -676,7 +688,8 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
                goto nla_put_failure;
        if (nla_put_via(skb, rt->rt_via_family, rt->rt_via, rt->rt_via_alen))
                goto nla_put_failure;
-       if (rt->rt_dev && nla_put_u32(skb, RTA_OIF, rt->rt_dev->ifindex))
+       dev = rtnl_dereference(rt->rt_dev);
+       if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex))
                goto nla_put_failure;
        if (nla_put_labels(skb, RTA_DST, 1, &label))
                goto nla_put_failure;
@@ -692,6 +705,8 @@ nla_put_failure:
 static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
 {
        struct net *net = sock_net(skb->sk);
+       struct mpls_route __rcu **platform_label;
+       size_t platform_labels;
        unsigned int index;
 
        ASSERT_RTNL();
@@ -700,9 +715,11 @@ static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
        if (index < 16)
                index = 16;
 
-       for (; index < net->mpls.platform_labels; index++) {
+       platform_label = rtnl_dereference(net->mpls.platform_label);
+       platform_labels = net->mpls.platform_labels;
+       for (; index < platform_labels; index++) {
                struct mpls_route *rt;
-               rt = net->mpls.platform_label[index];
+               rt = rtnl_dereference(platform_label[index]);
                if (!rt)
                        continue;
 
@@ -780,7 +797,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
                rt0 = mpls_rt_alloc(lo->addr_len);
                if (!rt0)
                        goto nort0;
-               rt0->rt_dev = lo;
+               RCU_INIT_POINTER(rt0->rt_dev, lo);
                rt0->rt_protocol = RTPROT_KERNEL;
                rt0->rt_via_family = AF_PACKET;
                memcpy(rt0->rt_via, lo->dev_addr, lo->addr_len);
@@ -790,7 +807,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
                rt2 = mpls_rt_alloc(lo->addr_len);
                if (!rt2)
                        goto nort2;
-               rt2->rt_dev = lo;
+               RCU_INIT_POINTER(rt2->rt_dev, lo);
                rt2->rt_protocol = RTPROT_KERNEL;
                rt2->rt_via_family = AF_PACKET;
                memcpy(rt2->rt_via, lo->dev_addr, lo->addr_len);
@@ -798,7 +815,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
 
        rtnl_lock();
        /* Remember the original table */
-       old = net->mpls.platform_label;
+       old = rtnl_dereference(net->mpls.platform_label);
        old_limit = net->mpls.platform_labels;
 
        /* Free any labels beyond the new table */
@@ -815,19 +832,19 @@ static int resize_platform_label_table(struct net *net, size_t limit)
        /* If needed set the predefined labels */
        if ((old_limit <= LABEL_IPV6_EXPLICIT_NULL) &&
            (limit > LABEL_IPV6_EXPLICIT_NULL)) {
-               labels[LABEL_IPV6_EXPLICIT_NULL] = rt2;
+               RCU_INIT_POINTER(labels[LABEL_IPV6_EXPLICIT_NULL], rt2);
                rt2 = NULL;
        }
 
        if ((old_limit <= LABEL_IPV4_EXPLICIT_NULL) &&
            (limit > LABEL_IPV4_EXPLICIT_NULL)) {
-               labels[LABEL_IPV4_EXPLICIT_NULL] = rt0;
+               RCU_INIT_POINTER(labels[LABEL_IPV4_EXPLICIT_NULL], rt0);
                rt0 = NULL;
        }
 
        /* Update the global pointers */
        net->mpls.platform_labels = limit;
-       net->mpls.platform_label = labels;
+       rcu_assign_pointer(net->mpls.platform_label, labels);
 
        rtnl_unlock();
 
@@ -903,6 +920,8 @@ static int mpls_net_init(struct net *net)
 
 static void mpls_net_exit(struct net *net)
 {
+       struct mpls_route __rcu **platform_label;
+       size_t platform_labels;
        struct ctl_table *table;
        unsigned int index;
 
@@ -910,8 +929,8 @@ static void mpls_net_exit(struct net *net)
        unregister_net_sysctl_table(net->mpls.ctl);
        kfree(table);
 
-       /* An rcu grace period haselapsed since there was a device in
-        * the network namespace (and thus the last in fqlight packet)
+       /* An rcu grace period has passed since there was a device in
+        * the network namespace (and thus the last in flight packet)
         * left this network namespace.  This is because
         * unregister_netdevice_many and netdev_run_todo has completed
         * for each network device that was in this network namespace.
@@ -920,14 +939,16 @@ static void mpls_net_exit(struct net *net)
         * freeing the platform_label table.
         */
        rtnl_lock();
-       for (index = 0; index < net->mpls.platform_labels; index++) {
-               struct mpls_route *rt = net->mpls.platform_label[index];
-               rcu_assign_pointer(net->mpls.platform_label[index], NULL);
+       platform_label = rtnl_dereference(net->mpls.platform_label);
+       platform_labels = net->mpls.platform_labels;
+       for (index = 0; index < platform_labels; index++) {
+               struct mpls_route *rt = rtnl_dereference(platform_label[index]);
+               RCU_INIT_POINTER(platform_label[index], NULL);
                mpls_rt_free(rt);
        }
        rtnl_unlock();
 
-       kvfree(net->mpls.platform_label);
+       kvfree(platform_label);
 }
 
 static struct pernet_operations mpls_net_ops = {