net_sched: use tcf_queue_work() in fw filter

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

Reported-by: Chris Mi <chrism@mellanox.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 3 deletions

diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index 941245ad07fd..99183b8621ec 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -46,7 +46,10 @@ struct fw_filter {
 #endif /* CONFIG_NET_CLS_IND */
         struct tcf_exts         exts;
         struct tcf_proto        *tp;
-        struct rcu_head         rcu;
+        union {
+                struct work_struct      work;
+                struct rcu_head         rcu;
+        };
 };
 
 static u32 fw_hash(u32 handle)
@@ -119,12 +122,22 @@ static int fw_init(struct tcf_proto *tp)
         return 0;
 }
 
-static void fw_delete_filter(struct rcu_head *head)
+static void fw_delete_filter_work(struct work_struct *work)
 {
-        struct fw_filter *f = container_of(head, struct fw_filter, rcu);
+        struct fw_filter *f = container_of(work, struct fw_filter, work);
 
+        rtnl_lock();
         tcf_exts_destroy(&f->exts);
         kfree(f);
+        rtnl_unlock();
+}
+
+static void fw_delete_filter(struct rcu_head *head)
+{
+        struct fw_filter *f = container_of(head, struct fw_filter, rcu);
+
+        INIT_WORK(&f->work, fw_delete_filter_work);
+        tcf_queue_work(&f->work);
 }
 
 static void fw_destroy(struct tcf_proto *tp)