net: sched: cls_rcvp, complete rcu conversion

This completes the cls_rsvp conversion to RCU safe
copy, update semantics.

As a result all cases of tcf_exts_change occur on
empty lists now.

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

1 files changed, 41 insertions, 3 deletions

diff --git a/net/sched/cls_rsvp.h b/net/sched/cls_rsvp.h
index 1c64a09753c4..6bb55f277a5a 100644
--- a/net/sched/cls_rsvp.h
+++ b/net/sched/cls_rsvp.h
@@ -222,6 +222,33 @@ matched:
         return -1;
 }
 
+static void rsvp_replace(struct tcf_proto *tp, struct rsvp_filter *n, u32 h)
+{
+        struct rsvp_head *head = rtnl_dereference(tp->root);
+        struct rsvp_session *s;
+        struct rsvp_filter __rcu **ins;
+        struct rsvp_filter *pins;
+        unsigned int h1 = h & 0xFF;
+        unsigned int h2 = (h >> 8) & 0xFF;
+
+        for (s = rtnl_dereference(head->ht[h1]); s;
+             s = rtnl_dereference(s->next)) {
+                for (ins = &s->ht[h2], pins = rtnl_dereference(*ins); ;
+                     ins = &pins->next, pins = rtnl_dereference(*ins)) {
+                        if (pins->handle == h) {
+                                RCU_INIT_POINTER(n->next, pins->next);
+                                rcu_assign_pointer(*ins, n);
+                                return;
+                        }
+                }
+        }
+
+        /* Something went wrong if we are trying to replace a non-existant
+         * node. Mind as well halt instead of silently failing.
+         */
+        BUG_ON(1);
+}
+
 static unsigned long rsvp_get(struct tcf_proto *tp, u32 handle)
 {
         struct rsvp_head *head = rtnl_dereference(tp->root);
@@ -454,15 +481,26 @@ static int rsvp_change(struct net *net, struct sk_buff *in_skb,
         f = (struct rsvp_filter *)*arg;
         if (f) {
                 /* Node exists: adjust only classid */
+                struct rsvp_filter *n;
 
                 if (f->handle != handle && handle)
                         goto errout2;
+
+                n = kmemdup(f, sizeof(*f), GFP_KERNEL);
+                if (!n) {
+                        err = -ENOMEM;
+                        goto errout2;
+                }
+
+                tcf_exts_init(&n->exts, TCA_RSVP_ACT, TCA_RSVP_POLICE);
+
                 if (tb[TCA_RSVP_CLASSID]) {
-                        f->res.classid = nla_get_u32(tb[TCA_RSVP_CLASSID]);
-                        tcf_bind_filter(tp, &f->res, base);
+                        n->res.classid = nla_get_u32(tb[TCA_RSVP_CLASSID]);
+                        tcf_bind_filter(tp, &n->res, base);
                 }
 
-                tcf_exts_change(tp, &f->exts, &e);
+                tcf_exts_change(tp, &n->exts, &e);
+                rsvp_replace(tp, n, handle);
                 return 0;
         }