net_sched: use tcf_queue_work() in tcindex 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, 33 insertions, 5 deletions

diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
index 14a7e08b2fa9..beaa95e09c25 100644
--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -27,14 +27,20 @@
 struct tcindex_filter_result {
         struct tcf_exts         exts;
         struct tcf_result       res;
-        struct rcu_head         rcu;
+        union {
+                struct work_struct      work;
+                struct rcu_head         rcu;
+        };
 };
 
 struct tcindex_filter {
         u16 key;
         struct tcindex_filter_result result;
         struct tcindex_filter __rcu *next;
-        struct rcu_head rcu;
+        union {
+                struct work_struct work;
+                struct rcu_head rcu;
+        };
 };
 
 
@@ -133,12 +139,34 @@ static int tcindex_init(struct tcf_proto *tp)
         return 0;
 }
 
+static void tcindex_destroy_rexts_work(struct work_struct *work)
+{
+        struct tcindex_filter_result *r;
+
+        r = container_of(work, struct tcindex_filter_result, work);
+        rtnl_lock();
+        tcf_exts_destroy(&r->exts);
+        rtnl_unlock();
+}
+
 static void tcindex_destroy_rexts(struct rcu_head *head)
 {
         struct tcindex_filter_result *r;
 
         r = container_of(head, struct tcindex_filter_result, rcu);
-        tcf_exts_destroy(&r->exts);
+        INIT_WORK(&r->work, tcindex_destroy_rexts_work);
+        tcf_queue_work(&r->work);
+}
+
+static void tcindex_destroy_fexts_work(struct work_struct *work)
+{
+        struct tcindex_filter *f = container_of(work, struct tcindex_filter,
+                                                work);
+
+        rtnl_lock();
+        tcf_exts_destroy(&f->result.exts);
+        kfree(f);
+        rtnl_unlock();
 }
 
 static void tcindex_destroy_fexts(struct rcu_head *head)
@@ -146,8 +174,8 @@ static void tcindex_destroy_fexts(struct rcu_head *head)
         struct tcindex_filter *f = container_of(head, struct tcindex_filter,
                                                 rcu);
 
-        tcf_exts_destroy(&f->result.exts);
-        kfree(f);
+        INIT_WORK(&f->work, tcindex_destroy_fexts_work);
+        tcf_queue_work(&f->work);
 }
 
 static int tcindex_delete(struct tcf_proto *tp, void *arg, bool *last)