[Patch net 03/16] net_sched: use tcf_queue_work() in bpf 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_bpf.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 520c5027646a..037a3ae86829 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -49,7 +49,10 @@ struct cls_bpf_prog {
        struct sock_filter *bpf_ops;
        const char *bpf_name;
        struct tcf_proto *tp;
-       struct rcu_head rcu;
+       union {
+               struct work_struct work;
+               struct rcu_head rcu;
+       };
 };
 
 static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
@@ -257,9 +260,21 @@ static void __cls_bpf_delete_prog(struct cls_bpf_prog 
*prog)
        kfree(prog);
 }
 
+static void cls_bpf_delete_prog_work(struct work_struct *work)
+{
+       struct cls_bpf_prog *prog = container_of(work, struct cls_bpf_prog, 
work);
+
+       rtnl_lock();
+       __cls_bpf_delete_prog(prog);
+       rtnl_unlock();
+}
+
 static void cls_bpf_delete_prog_rcu(struct rcu_head *rcu)
 {
-       __cls_bpf_delete_prog(container_of(rcu, struct cls_bpf_prog, rcu));
+       struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu);
+
+       INIT_WORK(&prog->work, cls_bpf_delete_prog_work);
+       tcf_queue_work(&prog->work);
 }
 
 static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog)
-- 
2.13.0