[Patch net 10/16] net_sched: use tcf_queue_work() in route filter

[Cong Wang]

Defer the tcf_exts_destroy() in RCU callback to
tc filter workqueue and get RTNL lock.

Reported-by: Chris Mi <chr...@mellanox.com>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Jiri Pirko <j...@resnulli.us>
Cc: John Fastabend <john.fastab...@gmail.com>
Cc: Jamal Hadi Salim <j...@mojatatu.com>
Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/sched/cls_route.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index 9ddde65915d2..4b14ccd8b8f2 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -57,7 +57,10 @@ struct route4_filter {
        u32                     handle;
        struct route4_bucket    *bkt;
        struct tcf_proto        *tp;
-       struct rcu_head         rcu;
+       union {
+               struct work_struct      work;
+               struct rcu_head         rcu;
+       };
 };
 
 #define ROUTE4_FAILURE ((struct route4_filter *)(-1L))
@@ -254,12 +257,22 @@ static int route4_init(struct tcf_proto *tp)
        return 0;
 }
 
-static void route4_delete_filter(struct rcu_head *head)
+static void route4_delete_filter_work(struct work_struct *work)
 {
-       struct route4_filter *f = container_of(head, struct route4_filter, rcu);
+       struct route4_filter *f = container_of(work, struct route4_filter, 
work);
 
+       rtnl_lock();
        tcf_exts_destroy(&f->exts);
        kfree(f);
+       rtnl_unlock();
+}
+
+static void route4_delete_filter(struct rcu_head *head)
+{
+       struct route4_filter *f = container_of(head, struct route4_filter, rcu);
+
+       INIT_WORK(&f->work, route4_delete_filter_work);
+       tcf_queue_work(&f->work);
 }
 
 static void route4_destroy(struct tcf_proto *tp)
-- 
2.13.0