[Patch net 10/13] cls_route: use tcf_exts_get_net() before call_rcu()

[Cong Wang]

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <luc...@mojatatu.com>
Cc: Jamal Hadi Salim <j...@mojatatu.com>
Cc: Jiri Pirko <j...@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/sched/cls_route.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index 4b14ccd8b8f2..ac9a5b8825b9 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -257,13 +257,19 @@ static int route4_init(struct tcf_proto *tp)
        return 0;
 }
 
+static void __route4_delete_filter(struct route4_filter *f)
+{
+       tcf_exts_destroy(&f->exts);
+       tcf_exts_put_net(&f->exts);
+       kfree(f);
+}
+
 static void route4_delete_filter_work(struct work_struct *work)
 {
        struct route4_filter *f = container_of(work, struct route4_filter, 
work);
 
        rtnl_lock();
-       tcf_exts_destroy(&f->exts);
-       kfree(f);
+       __route4_delete_filter(f);
        rtnl_unlock();
 }
 
@@ -297,7 +303,10 @@ static void route4_destroy(struct tcf_proto *tp)
                                        next = rtnl_dereference(f->next);
                                        RCU_INIT_POINTER(b->ht[h2], next);
                                        tcf_unbind_filter(tp, &f->res);
-                                       call_rcu(&f->rcu, route4_delete_filter);
+                                       if (tcf_exts_get_net(&f->exts))
+                                               call_rcu(&f->rcu, 
route4_delete_filter);
+                                       else
+                                               __route4_delete_filter(f);
                                }
                        }
                        RCU_INIT_POINTER(head->table[h1], NULL);
@@ -338,6 +347,7 @@ static int route4_delete(struct tcf_proto *tp, void *arg, 
bool *last)
 
                        /* Delete it */
                        tcf_unbind_filter(tp, &f->res);
+                       tcf_exts_get_net(&f->exts);
                        call_rcu(&f->rcu, route4_delete_filter);
 
                        /* Strip RTNL protected tree */
@@ -541,6 +551,7 @@ static int route4_change(struct net *net, struct sk_buff 
*in_skb,
        *arg = f;
        if (fold) {
                tcf_unbind_filter(tp, &fold->res);
+               tcf_exts_get_net(&fold->exts);
                call_rcu(&fold->rcu, route4_delete_filter);
        }
        return 0;
-- 
2.13.0