[Patch net 06/16] net_sched: use tcf_queue_work() in flower 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_flower.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index b480d7c792ba..5b5722c8b32c 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -87,7 +87,10 @@ struct cls_fl_filter {
        struct list_head list;
        u32 handle;
        u32 flags;
-       struct rcu_head rcu;
+       union {
+               struct work_struct work;
+               struct rcu_head rcu;
+       };
        struct net_device *hw_dev;
 };
 
@@ -215,12 +218,22 @@ static int fl_init(struct tcf_proto *tp)
        return 0;
 }
 
-static void fl_destroy_filter(struct rcu_head *head)
+static void fl_destroy_filter_work(struct work_struct *work)
 {
-       struct cls_fl_filter *f = container_of(head, struct cls_fl_filter, rcu);
+       struct cls_fl_filter *f = container_of(work, struct cls_fl_filter, 
work);
 
+       rtnl_lock();
        tcf_exts_destroy(&f->exts);
        kfree(f);
+       rtnl_unlock();
+}
+
+static void fl_destroy_filter(struct rcu_head *head)
+{
+       struct cls_fl_filter *f = container_of(head, struct cls_fl_filter, rcu);
+
+       INIT_WORK(&f->work, fl_destroy_filter_work);
+       tcf_queue_work(&f->work);
 }
 
 static void fl_hw_destroy_filter(struct tcf_proto *tp, struct cls_fl_filter *f)
-- 
2.13.0