1 files changed, 48 insertions, 31 deletions

diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index cacf01bd04f0..d61a801222c1 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -22,17 +22,17 @@ struct cls_cgroup_head {
         u32                     handle;
         struct tcf_exts         exts;
         struct tcf_ematch_tree  ematches;
+        struct tcf_proto        *tp;
+        struct rcu_head         rcu;
 };
 
 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
                                struct tcf_result *res)
 {
-        struct cls_cgroup_head *head = tp->root;
+        struct cls_cgroup_head *head = rcu_dereference_bh(tp->root);
         u32 classid;
 
-        rcu_read_lock();
         classid = task_cls_state(current)->classid;
-        rcu_read_unlock();
 
         /*
          * Due to the nature of the classifier it is required to ignore all
@@ -80,13 +80,25 @@ static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 };
 
+static void cls_cgroup_destroy_rcu(struct rcu_head *root)
+{
+        struct cls_cgroup_head *head = container_of(root,
+                                                    struct cls_cgroup_head,
+                                                    rcu);
+
+        tcf_exts_destroy(&head->exts);
+        tcf_em_tree_destroy(&head->ematches);
+        kfree(head);
+}
+
 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
                              struct tcf_proto *tp, unsigned long base,
                              u32 handle, struct nlattr **tca,
                              unsigned long *arg, bool ovr)
 {
         struct nlattr *tb[TCA_CGROUP_MAX + 1];
-        struct cls_cgroup_head *head = tp->root;
+        struct cls_cgroup_head *head = rtnl_dereference(tp->root);
+        struct cls_cgroup_head *new;
         struct tcf_ematch_tree t;
         struct tcf_exts e;
         int err;
@@ -94,53 +106,58 @@ static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
         if (!tca[TCA_OPTIONS])
                 return -EINVAL;
 
-        if (head == NULL) {
-                if (!handle)
-                        return -EINVAL;
-
-                head = kzalloc(sizeof(*head), GFP_KERNEL);
-                if (head == NULL)
-                        return -ENOBUFS;
+        if (!head && !handle)
+                return -EINVAL;
 
-                tcf_exts_init(&head->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
-                head->handle = handle;
+        if (head && handle != head->handle)
+                return -ENOENT;
 
-                tcf_tree_lock(tp);
-                tp->root = head;
-                tcf_tree_unlock(tp);
-        }
+        new = kzalloc(sizeof(*head), GFP_KERNEL);
+        if (!new)
+                return -ENOBUFS;
 
-        if (handle != head->handle)
-                return -ENOENT;
+        tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
+        if (head)
+                new->handle = head->handle;
+        else
+                new->handle = handle;
 
+        new->tp = tp;
         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
                                cgroup_policy);
         if (err < 0)
-                return err;
+                goto errout;
 
         tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
         err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
         if (err < 0)
-                return err;
+                goto errout;
 
         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
-        if (err < 0)
-                return err;
+        if (err < 0) {
+                tcf_exts_destroy(&e);
+                goto errout;
+        }
 
-        tcf_exts_change(tp, &head->exts, &e);
-        tcf_em_tree_change(tp, &head->ematches, &t);
+        tcf_exts_change(tp, &new->exts, &e);
+        tcf_em_tree_change(tp, &new->ematches, &t);
 
+        rcu_assign_pointer(tp->root, new);
+        if (head)
+                call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
         return 0;
+errout:
+        kfree(new);
+        return err;
 }
 
 static void cls_cgroup_destroy(struct tcf_proto *tp)
 {
-        struct cls_cgroup_head *head = tp->root;
+        struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 
         if (head) {
-                tcf_exts_destroy(tp, &head->exts);
-                tcf_em_tree_destroy(tp, &head->ematches);
-                kfree(head);
+                RCU_INIT_POINTER(tp->root, NULL);
+                call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
         }
 }
 
@@ -151,7 +168,7 @@ static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 
 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 {
-        struct cls_cgroup_head *head = tp->root;
+        struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 
         if (arg->count < arg->skip)
                 goto skip;
@@ -167,7 +184,7 @@ skip:
 static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
                            struct sk_buff *skb, struct tcmsg *t)
 {
-        struct cls_cgroup_head *head = tp->root;
+        struct cls_cgroup_head *head = rtnl_dereference(tp->root);
         unsigned char *b = skb_tail_pointer(skb);
         struct nlattr *nest;