1 files changed, 29 insertions, 6 deletions

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index c6452e3bfc6a..3038a82f6591 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -477,9 +477,12 @@ static void __tcf_chain_put(struct tcf_chain *chain, bool by_act,
         mutex_unlock(&block->lock);
 
         /* The last dropped non-action reference will trigger notification. */
-        if (is_last && !by_act)
+        if (is_last && !by_act) {
                 tc_chain_notify_delete(tmplt_ops, tmplt_priv, chain_index,
                                        block, NULL, 0, 0, false);
+                /* Last reference to chain, no need to lock. */
+                chain->flushing = false;
+        }
 
         if (refcnt == 0) {
                 tc_chain_tmplt_del(tmplt_ops, tmplt_priv);
@@ -511,6 +514,7 @@ static void tcf_chain_flush(struct tcf_chain *chain)
         tp = tcf_chain_dereference(chain->filter_chain, chain);
         RCU_INIT_POINTER(chain->filter_chain, NULL);
         tcf_chain0_head_change(chain, NULL);
+        chain->flushing = true;
         mutex_unlock(&chain->filter_chain_lock);
 
         while (tp) {
@@ -1610,15 +1614,20 @@ static struct tcf_proto *tcf_chain_tp_prev(struct tcf_chain *chain,
         return tcf_chain_dereference(*chain_info->pprev, chain);
 }
 
-static void tcf_chain_tp_insert(struct tcf_chain *chain,
-                                struct tcf_chain_info *chain_info,
-                                struct tcf_proto *tp)
+static int tcf_chain_tp_insert(struct tcf_chain *chain,
+                               struct tcf_chain_info *chain_info,
+                               struct tcf_proto *tp)
 {
+        if (chain->flushing)
+                return -EAGAIN;
+
         if (*chain_info->pprev == chain->filter_chain)
                 tcf_chain0_head_change(chain, tp);
         tcf_proto_get(tp);
         RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain, chain_info));
         rcu_assign_pointer(*chain_info->pprev, tp);
+
+        return 0;
 }
 
 static void tcf_chain_tp_remove(struct tcf_chain *chain,
@@ -1649,18 +1658,22 @@ static struct tcf_proto *tcf_chain_tp_insert_unique(struct tcf_chain *chain,
 {
         struct tcf_chain_info chain_info;
         struct tcf_proto *tp;
+        int err = 0;
 
         mutex_lock(&chain->filter_chain_lock);
 
         tp = tcf_chain_tp_find(chain, &chain_info,
                                protocol, prio, false);
         if (!tp)
-                tcf_chain_tp_insert(chain, &chain_info, tp_new);
+                err = tcf_chain_tp_insert(chain, &chain_info, tp_new);
         mutex_unlock(&chain->filter_chain_lock);
 
         if (tp) {
                 tcf_proto_destroy(tp_new, NULL);
                 tp_new = tp;
+        } else if (err) {
+                tcf_proto_destroy(tp_new, NULL);
+                tp_new = ERR_PTR(err);
         }
 
         return tp_new;
@@ -1943,6 +1956,11 @@ replay:
         if (tp == NULL) {
                 struct tcf_proto *tp_new = NULL;
 
+                if (chain->flushing) {
+                        err = -EAGAIN;
+                        goto errout_locked;
+                }
+
                 /* Proto-tcf does not exist, create new one */
 
                 if (tca[TCA_KIND] == NULL || !protocol) {
@@ -1966,11 +1984,15 @@ replay:
                                           protocol, prio, chain, extack);
                 if (IS_ERR(tp_new)) {
                         err = PTR_ERR(tp_new);
-                        goto errout;
+                        goto errout_tp;
                 }
 
                 tp_created = 1;
                 tp = tcf_chain_tp_insert_unique(chain, tp_new, protocol, prio);
+                if (IS_ERR(tp)) {
+                        err = PTR_ERR(tp);
+                        goto errout_tp;
+                }
         } else {
                 mutex_unlock(&chain->filter_chain_lock);
         }
@@ -2011,6 +2033,7 @@ replay:
 errout:
         if (err && tp_created)
                 tcf_chain_tp_delete_empty(chain, tp, NULL);
+errout_tp:
         if (chain) {
                 if (tp && !IS_ERR(tp))
                         tcf_proto_put(tp, NULL);