net_sched: convert tcf_exts from list to pointer array

As pointed out by Jamal, an action could be shared by
multiple filters, so we can't use list to chain them
any more after we get rid of the original tc_action.
Instead, we could just save pointers to these actions
in tcf_exts, since they are refcount'ed, so convert
the list to an array of pointers.

The "ugly" part is the action API still accepts list
as a parameter, I just introduce a helper function to
convert the array of pointers to a list, instead of
relying on the C99 feature to iterate the array.

Fixes: a85a970af265 ("net_sched: move tc_action into tcf_common")
Reported-by: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 14 deletions

diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index 00dd5c4c1d0a..c99508d426cc 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -59,7 +59,8 @@ tcf_unbind_filter(struct tcf_proto *tp, struct tcf_result *r)
 struct tcf_exts {
 #ifdef CONFIG_NET_CLS_ACT
 	__u32	type; /* for backward compat(TCA_OLD_COMPAT) */
-	struct list_head actions;
+	int nr_actions;
+	struct tc_action **actions;
 #endif
 	/* Map to export classifier specific extension TLV types to the
 	 * generic extensions API. Unsupported extensions must be set to 0.
@@ -72,7 +73,10 @@ static inline void tcf_exts_init(struct tcf_exts *exts, int action, int police)
 {
 #ifdef CONFIG_NET_CLS_ACT
 	exts->type = 0;
-	INIT_LIST_HEAD(&exts->actions);
+	exts->nr_actions = 0;
+	exts->actions = kcalloc(TCA_ACT_MAX_PRIO, sizeof(struct tc_action *),
+				GFP_KERNEL);
+	WARN_ON(!exts->actions); /* TODO: propagate the error to callers */
 #endif
 	exts->action = action;
 	exts->police = police;
@@ -89,7 +93,7 @@ static inline int
 tcf_exts_is_predicative(struct tcf_exts *exts)
 {
 #ifdef CONFIG_NET_CLS_ACT
-	return !list_empty(&exts->actions);
+	return exts->nr_actions;
 #else
 	return 0;
 #endif
@@ -108,6 +112,20 @@ tcf_exts_is_available(struct tcf_exts *exts)
 	return tcf_exts_is_predicative(exts);
 }
 
+static inline void tcf_exts_to_list(const struct tcf_exts *exts,
+				    struct list_head *actions)
+{
+#ifdef CONFIG_NET_CLS_ACT
+	int i;
+
+	for (i = 0; i < exts->nr_actions; i++) {
+		struct tc_action *a = exts->actions[i];
+
+		list_add(&a->list, actions);
+	}
+#endif
+}
+
 /**
  * tcf_exts_exec - execute tc filter extensions
  * @skb: socket buffer
@@ -124,27 +142,21 @@ tcf_exts_exec(struct sk_buff *skb, struct tcf_exts *exts,
 	       struct tcf_result *res)
 {
 #ifdef CONFIG_NET_CLS_ACT
-	if (!list_empty(&exts->actions))
-		return tcf_action_exec(skb, &exts->actions, res);
+	if (exts->nr_actions)
+		return tcf_action_exec(skb, exts->actions, exts->nr_actions,
+				       res);
 #endif
 	return 0;
 }
 
 #ifdef CONFIG_NET_CLS_ACT
 
-#define tc_no_actions(_exts) \
-	(list_empty(&(_exts)->actions))
-
-#define tc_for_each_action(_a, _exts) \
-	list_for_each_entry(_a, &(_exts)->actions, list)
-
-#define tc_single_action(_exts) \
-	(list_is_singular(&(_exts)->actions))
+#define tc_no_actions(_exts)  ((_exts)->nr_actions == 0)
+#define tc_single_action(_exts) ((_exts)->nr_actions == 1)
 
 #else /* CONFIG_NET_CLS_ACT */
 
 #define tc_no_actions(_exts) true
-#define tc_for_each_action(_a, _exts) while ((void)(_a), 0)
 #define tc_single_action(_exts) false
 
 #endif /* CONFIG_NET_CLS_ACT */