net_sched: fix regression in tc_action_ops

list_for_each_entry(a, &act_base, head) doesn't
exit with a = NULL if we reached the end of the list.

tcf_unregister_action(), tc_lookup_action_n() and tc_lookup_action()
need fixes.

Remove tc_lookup_action_id() as its unused and not worth 'fixing'

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 1f747c26c48b ("net_sched: convert tc_action_ops to use struct list_head")
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 40 deletions

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 8114fef308d9..dce2b6ecdbd8 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -291,12 +291,12 @@ int tcf_unregister_action(struct tc_action_ops *act)
         int err = -ENOENT;
 
         write_lock(&act_mod_lock);
-        list_for_each_entry(a, &act_base, head)
-                if (a == act)
+        list_for_each_entry(a, &act_base, head) {
+                if (a == act) {
+                        list_del(&act->head);
+                        err = 0;
                         break;
-        if (a) {
-                list_del(&act->head);
-                err = 0;
+                }
         }
         write_unlock(&act_mod_lock);
         return err;
@@ -306,68 +306,41 @@ EXPORT_SYMBOL(tcf_unregister_action);
 /* lookup by name */
 static struct tc_action_ops *tc_lookup_action_n(char *kind)
 {
-        struct tc_action_ops *a = NULL;
+        struct tc_action_ops *a, *res = NULL;
 
         if (kind) {
                 read_lock(&act_mod_lock);
                 list_for_each_entry(a, &act_base, head) {
                         if (strcmp(kind, a->kind) == 0) {
-                                if (!try_module_get(a->owner)) {
-                                        read_unlock(&act_mod_lock);
-                                        return NULL;
-                                }
+                                if (try_module_get(a->owner))
+                                        res = a;
                                 break;
                         }
                 }
                 read_unlock(&act_mod_lock);
         }
-        return a;
+        return res;
 }
 
 /* lookup by nlattr */
 static struct tc_action_ops *tc_lookup_action(struct nlattr *kind)
 {
-        struct tc_action_ops *a = NULL;
+        struct tc_action_ops *a, *res = NULL;
 
         if (kind) {
                 read_lock(&act_mod_lock);
                 list_for_each_entry(a, &act_base, head) {
                         if (nla_strcmp(kind, a->kind) == 0) {
-                                if (!try_module_get(a->owner)) {
-                                        read_unlock(&act_mod_lock);
-                                        return NULL;
-                                }
+                                if (try_module_get(a->owner))
+                                        res = a;
                                 break;
                         }
                 }
                 read_unlock(&act_mod_lock);
         }
-        return a;
+        return res;
 }
 
-#if 0
-/* lookup by id */
-static struct tc_action_ops *tc_lookup_action_id(u32 type)
-{
-        struct tc_action_ops *a = NULL;
-
-        if (type) {
-                read_lock(&act_mod_lock);
-                for (a = act_base; a; a = a->next) {
-                        if (a->type == type) {
-                                if (!try_module_get(a->owner)) {
-                                        read_unlock(&act_mod_lock);
-                                        return NULL;
-                                }
-                                break;
-                        }
-                }
-                read_unlock(&act_mod_lock);
-        }
-        return a;
-}
-#endif
-
 int tcf_action_exec(struct sk_buff *skb, const struct list_head *actions,
                     struct tcf_result *res)
 {