net: sched: implement action-specific terse dump

Allow user to request action terse dump with new flag value
TCA_FLAG_TERSE_DUMP. Only output essential action info in terse dump (kind,
stats, index and cookie, if set by the user when creating the action). This
is different from filter terse dump where index is excluded (filter can be
identified by its own handle).

Move tcf_action_dump_terse() function to the beginning of source file in
order to call it from tcf_dump_walker().

Signed-off-by: Vlad Buslov <vlad@buslov.dev>
Suggested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Link: https://lore.kernel.org/r/20201102201243.287486-1-vlad@buslov.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/uapi/linux/rtnetlink.h

@@ -770,8 +770,12 @@ enum {
  * actions in a dump. All dump responses will contain the number of actions
  * being dumped stored in for user app's consumption in TCA_ROOT_COUNT
  *
+ * TCA_FLAG_TERSE_DUMP user->kernel to request terse (brief) dump that only
+ * includes essential action info (kind, index, etc.)
+ *
  */
 #define TCA_FLAG_LARGE_DUMP_ON		(1 << 0)
+#define TCA_FLAG_TERSE_DUMP		(1 << 1)
 
 /* New extended info filters for IFLA_EXT_MASK */
 #define RTEXT_FILTER_VF		(1 << 0)

net/sched/act_api.c

@@ -215,6 +215,36 @@ static size_t tcf_action_fill_size(const struct tc_action *act)
 	return sz;
 }
 
+static int
+tcf_action_dump_terse(struct sk_buff *skb, struct tc_action *a, bool from_act)
+{
+	unsigned char *b = skb_tail_pointer(skb);
+	struct tc_cookie *cookie;
+
+	if (nla_put_string(skb, TCA_KIND, a->ops->kind))
+		goto nla_put_failure;
+	if (tcf_action_copy_stats(skb, a, 0))
+		goto nla_put_failure;
+	if (from_act && nla_put_u32(skb, TCA_ACT_INDEX, a->tcfa_index))
+		goto nla_put_failure;
+
+	rcu_read_lock();
+	cookie = rcu_dereference(a->act_cookie);
+	if (cookie) {
+		if (nla_put(skb, TCA_ACT_COOKIE, cookie->len, cookie->data)) {
+			rcu_read_unlock();
+			goto nla_put_failure;
+		}
+	}
+	rcu_read_unlock();
+
+	return 0;
+
+nla_put_failure:
+	nlmsg_trim(skb, b);
+	return -1;
+}
+
 static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 			   struct netlink_callback *cb)
 {
@@ -248,7 +278,9 @@ static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 			index--;
 			goto nla_put_failure;
 		}
-		err = tcf_action_dump_1(skb, p, 0, 0);
+		err = (act_flags & TCA_FLAG_TERSE_DUMP) ?
+			tcf_action_dump_terse(skb, p, true) :
+			tcf_action_dump_1(skb, p, 0, 0);
 		if (err < 0) {
 			index--;
 			nlmsg_trim(skb, nest);
@@ -752,42 +784,14 @@ tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 	return a->ops->dump(skb, a, bind, ref);
 }
 
-static int
-tcf_action_dump_terse(struct sk_buff *skb, struct tc_action *a)
-{
-	unsigned char *b = skb_tail_pointer(skb);
-	struct tc_cookie *cookie;
-
-	if (nla_put_string(skb, TCA_KIND, a->ops->kind))
-		goto nla_put_failure;
-	if (tcf_action_copy_stats(skb, a, 0))
-		goto nla_put_failure;
-
-	rcu_read_lock();
-	cookie = rcu_dereference(a->act_cookie);
-	if (cookie) {
-		if (nla_put(skb, TCA_ACT_COOKIE, cookie->len, cookie->data)) {
-			rcu_read_unlock();
-			goto nla_put_failure;
-		}
-	}
-	rcu_read_unlock();
-
-	return 0;
-
-nla_put_failure:
-	nlmsg_trim(skb, b);
-	return -1;
-}
-
 int
 tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 {
 	int err = -EINVAL;
 	unsigned char *b = skb_tail_pointer(skb);
 	struct nlattr *nest;
 
-	if (tcf_action_dump_terse(skb, a))
+	if (tcf_action_dump_terse(skb, a, false))
 		goto nla_put_failure;
 
 	if (a->hw_stats != TCA_ACT_HW_STATS_ANY &&
@@ -832,7 +836,7 @@ int tcf_action_dump(struct sk_buff *skb, struct tc_action *actions[],
 		nest = nla_nest_start_noflag(skb, i + 1);
 		if (nest == NULL)
 			goto nla_put_failure;
-		err = terse ? tcf_action_dump_terse(skb, a) :
+		err = terse ? tcf_action_dump_terse(skb, a, false) :
 			tcf_action_dump_1(skb, a, bind, ref);
 		if (err < 0)
 			goto errout;
@@ -1469,7 +1473,8 @@ static int tcf_action_add(struct net *net, struct nlattr *nla,
 }
 
 static const struct nla_policy tcaa_policy[TCA_ROOT_MAX + 1] = {
-	[TCA_ROOT_FLAGS] = NLA_POLICY_BITFIELD32(TCA_FLAG_LARGE_DUMP_ON),
+	[TCA_ROOT_FLAGS] = NLA_POLICY_BITFIELD32(TCA_FLAG_LARGE_DUMP_ON |
+						 TCA_FLAG_TERSE_DUMP),
 	[TCA_ROOT_TIME_DELTA]      = { .type = NLA_U32 },
 };