[Patch net 02/16] net_sched: use tcf_queue_work() in basic 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_basic.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/net/sched/cls_basic.c b/net/sched/cls_basic.c
index d89ebafd2239..f177649a2419 100644
--- a/net/sched/cls_basic.c
+++ b/net/sched/cls_basic.c
@@ -34,7 +34,10 @@ struct basic_filter {
        struct tcf_result       res;
        struct tcf_proto        *tp;
        struct list_head        link;
-       struct rcu_head         rcu;
+       union {
+               struct work_struct      work;
+               struct rcu_head         rcu;
+       };
 };
 
 static int basic_classify(struct sk_buff *skb, const struct tcf_proto *tp,
@@ -82,15 +85,26 @@ static int basic_init(struct tcf_proto *tp)
        return 0;
 }
 
-static void basic_delete_filter(struct rcu_head *head)
+static void basic_delete_filter_work(struct work_struct *work)
 {
-       struct basic_filter *f = container_of(head, struct basic_filter, rcu);
+       struct basic_filter *f = container_of(work, struct basic_filter, work);
 
+       rtnl_lock();
        tcf_exts_destroy(&f->exts);
        tcf_em_tree_destroy(&f->ematches);
+       rtnl_unlock();
+
        kfree(f);
 }
 
+static void basic_delete_filter(struct rcu_head *head)
+{
+       struct basic_filter *f = container_of(head, struct basic_filter, rcu);
+
+       INIT_WORK(&f->work, basic_delete_filter_work);
+       tcf_queue_work(&f->work);
+}
+
 static void basic_destroy(struct tcf_proto *tp)
 {
        struct basic_head *head = rtnl_dereference(tp->root);
-- 
2.13.0