net/sched: fix filter flushing

When user instructs to remove all filters from chain, we cannot destroy
the chain as other actions may hold a reference. Also the put in errout
would try to destroy it again. So instead, just walk the chain and remove
all existing filters.

Fixes: 5bc1701881e3 ("net: sched: introduce multichain support for filters")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 85088ed07f6ab53ce3b87ec3fecae77bcbd19317..01a8b8b4bab870457e105aceb62dbd8b61606cec 100644 (file)
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -201,15 +201,22 @@ static struct tcf_chain *tcf_chain_create(struct tcf_block *block,
        return chain;
 }
 
-static void tcf_chain_destroy(struct tcf_chain *chain)
+static void tcf_chain_flush(struct tcf_chain *chain)
 {
        struct tcf_proto *tp;
 
-       list_del(&chain->list);
+       if (*chain->p_filter_chain)
+               RCU_INIT_POINTER(*chain->p_filter_chain, NULL);
        while ((tp = rtnl_dereference(chain->filter_chain)) != NULL) {
                RCU_INIT_POINTER(chain->filter_chain, tp->next);
                tcf_proto_destroy(tp);
        }
+}
+
+static void tcf_chain_destroy(struct tcf_chain *chain)
+{
+       list_del(&chain->list);
+       tcf_chain_flush(chain);
        kfree(chain);
 }
 
@@ -510,7 +517,7 @@ replay:
 
        if (n->nlmsg_type == RTM_DELTFILTER && prio == 0) {
                tfilter_notify_chain(net, skb, n, chain, RTM_DELTFILTER);
-               tcf_chain_destroy(chain);
+               tcf_chain_flush(chain);
                err = 0;
                goto errout;
        }