net: sched: fw use RCU

RCU'ify fw classifier.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index 861b03ccfed0a55007ceb001a297b05906b36ed3..006b45a67fdd4880f8e33574bb87cd122bfac718 100644 (file)
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -33,17 +33,20 @@
 
 struct fw_head {
        u32                     mask;
-       struct fw_filter        *ht[HTSIZE];
+       struct fw_filter __rcu  *ht[HTSIZE];
+       struct rcu_head         rcu;
 };
 
 struct fw_filter {
-       struct fw_filter        *next;
+       struct fw_filter __rcu  *next;
        u32                     id;
        struct tcf_result       res;
 #ifdef CONFIG_NET_CLS_IND
        int                     ifindex;
 #endif /* CONFIG_NET_CLS_IND */
        struct tcf_exts         exts;
+       struct tcf_proto        *tp;
+       struct rcu_head         rcu;
 };
 
 static u32 fw_hash(u32 handle)
@@ -56,14 +59,16 @@ static u32 fw_hash(u32 handle)
 static int fw_classify(struct sk_buff *skb, const struct tcf_proto *tp,
                          struct tcf_result *res)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rcu_dereference_bh(tp->root);
        struct fw_filter *f;
        int r;
        u32 id = skb->mark;
 
        if (head != NULL) {
                id &= head->mask;
-               for (f = head->ht[fw_hash(id)]; f; f = f->next) {
+
+               for (f = rcu_dereference_bh(head->ht[fw_hash(id)]); f;
+                    f = rcu_dereference_bh(f->next)) {
                        if (f->id == id) {
                                *res = f->res;
 #ifdef CONFIG_NET_CLS_IND
@@ -92,13 +97,14 @@ static int fw_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 
 static unsigned long fw_get(struct tcf_proto *tp, u32 handle)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f;
 
        if (head == NULL)
                return 0;
 
-       for (f = head->ht[fw_hash(handle)]; f; f = f->next) {
+       f = rtnl_dereference(head->ht[fw_hash(handle)]);
+       for (; f; f = rtnl_dereference(f->next)) {
                if (f->id == handle)
                        return (unsigned long)f;
        }
@@ -114,8 +120,11 @@ static int fw_init(struct tcf_proto *tp)
        return 0;
 }
 
-static void fw_delete_filter(struct tcf_proto *tp, struct fw_filter *f)
+static void fw_delete_filter(struct rcu_head *head)
 {
+       struct fw_filter *f = container_of(head, struct fw_filter, rcu);
+       struct tcf_proto *tp = f->tp;
+
        tcf_unbind_filter(tp, &f->res);
        tcf_exts_destroy(tp, &f->exts);
        kfree(f);
@@ -123,7 +132,7 @@ static void fw_delete_filter(struct tcf_proto *tp, struct fw_filter *f)
 
 static void fw_destroy(struct tcf_proto *tp)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f;
        int h;
 
@@ -131,29 +140,33 @@ static void fw_destroy(struct tcf_proto *tp)
                return;
 
        for (h = 0; h < HTSIZE; h++) {
-               while ((f = head->ht[h]) != NULL) {
-                       head->ht[h] = f->next;
-                       fw_delete_filter(tp, f);
+               while ((f = rtnl_dereference(head->ht[h])) != NULL) {
+                       RCU_INIT_POINTER(head->ht[h],
+                                        rtnl_dereference(f->next));
+                       call_rcu(&f->rcu, fw_delete_filter);
                }
        }
-       kfree(head);
+       RCU_INIT_POINTER(tp->root, NULL);
+       kfree_rcu(head, rcu);
 }
 
 static int fw_delete(struct tcf_proto *tp, unsigned long arg)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f = (struct fw_filter *)arg;
-       struct fw_filter **fp;
+       struct fw_filter __rcu **fp;
+       struct fw_filter *pfp;
 
        if (head == NULL || f == NULL)
                goto out;
 
-       for (fp = &head->ht[fw_hash(f->id)]; *fp; fp = &(*fp)->next) {
-               if (*fp == f) {
-                       tcf_tree_lock(tp);
-                       *fp = f->next;
-                       tcf_tree_unlock(tp);
-                       fw_delete_filter(tp, f);
+       fp = &head->ht[fw_hash(f->id)];
+
+       for (pfp = rtnl_dereference(*fp); pfp;
+            fp = &pfp->next, pfp = rtnl_dereference(*fp)) {
+               if (pfp == f) {
+                       RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));
+                       call_rcu(&f->rcu, fw_delete_filter);
                        return 0;
                }
        }
@@ -171,7 +184,7 @@ static int
 fw_change_attrs(struct net *net, struct tcf_proto *tp, struct fw_filter *f,
        struct nlattr **tb, struct nlattr **tca, unsigned long base, bool ovr)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rtnl_dereference(tp->root);
        struct tcf_exts e;
        u32 mask;
        int err;
@@ -220,7 +233,7 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
                     struct nlattr **tca,
                     unsigned long *arg, bool ovr)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f = (struct fw_filter *) *arg;
        struct nlattr *opt = tca[TCA_OPTIONS];
        struct nlattr *tb[TCA_FW_MAX + 1];
@@ -233,10 +246,42 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
        if (err < 0)
                return err;
 
-       if (f != NULL) {
+       if (f) {
+               struct fw_filter *pfp, *fnew;
+               struct fw_filter __rcu **fp;
+
                if (f->id != handle && handle)
                        return -EINVAL;
-               return fw_change_attrs(net, tp, f, tb, tca, base, ovr);
+
+               fnew = kzalloc(sizeof(struct fw_filter), GFP_KERNEL);
+               if (!fnew)
+                       return -ENOBUFS;
+
+               fnew->id = f->id;
+               fnew->res = f->res;
+#ifdef CONFIG_NET_CLS_IND
+               fnew->ifindex = f->ifindex;
+#endif /* CONFIG_NET_CLS_IND */
+               fnew->tp = f->tp;
+
+               err = fw_change_attrs(net, tp, fnew, tb, tca, base, ovr);
+               if (err < 0) {
+                       kfree(fnew);
+                       return err;
+               }
+
+               fp = &head->ht[fw_hash(fnew->id)];
+               for (pfp = rtnl_dereference(*fp); pfp;
+                    fp = &pfp->next, pfp = rtnl_dereference(*fp))
+                       if (pfp == f)
+                               break;
+
+               RCU_INIT_POINTER(fnew->next, rtnl_dereference(pfp->next));
+               rcu_assign_pointer(*fp, fnew);
+               call_rcu(&f->rcu, fw_delete_filter);
+
+               *arg = (unsigned long)fnew;
+               return err;
        }
 
        if (!handle)
@@ -252,9 +297,7 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
                        return -ENOBUFS;
                head->mask = mask;
 
-               tcf_tree_lock(tp);
-               tp->root = head;
-               tcf_tree_unlock(tp);
+               rcu_assign_pointer(tp->root, head);
        }
 
        f = kzalloc(sizeof(struct fw_filter), GFP_KERNEL);
@@ -263,15 +306,14 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
 
        tcf_exts_init(&f->exts, TCA_FW_ACT, TCA_FW_POLICE);
        f->id = handle;
+       f->tp = tp;
 
        err = fw_change_attrs(net, tp, f, tb, tca, base, ovr);
        if (err < 0)
                goto errout;
 
-       f->next = head->ht[fw_hash(handle)];
-       tcf_tree_lock(tp);
-       head->ht[fw_hash(handle)] = f;
-       tcf_tree_unlock(tp);
+       RCU_INIT_POINTER(f->next, head->ht[fw_hash(handle)]);
+       rcu_assign_pointer(head->ht[fw_hash(handle)], f);
 
        *arg = (unsigned long)f;
        return 0;
@@ -283,7 +325,7 @@ errout:
 
 static void fw_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rtnl_dereference(tp->root);
        int h;
 
        if (head == NULL)
@@ -295,7 +337,8 @@ static void fw_walk(struct tcf_proto *tp, struct tcf_walker *arg)
        for (h = 0; h < HTSIZE; h++) {
                struct fw_filter *f;
 
-               for (f = head->ht[h]; f; f = f->next) {
+               for (f = rtnl_dereference(head->ht[h]); f;
+                    f = rtnl_dereference(f->next)) {
                        if (arg->count < arg->skip) {
                                arg->count++;
                                continue;
@@ -312,7 +355,7 @@ static void fw_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 static int fw_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
                   struct sk_buff *skb, struct tcmsg *t)
 {
-       struct fw_head *head = tp->root;
+       struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f = (struct fw_filter *)fh;
        unsigned char *b = skb_tail_pointer(skb);
        struct nlattr *nest;