[PATCH net-next 2/4] net/sched: tc_dump_qdisc_root() refactor

[Eric Dumazet <edumazet@google.com>]

Change tc_fill_qdisc() to return -EMSGSIZE when skb is too small.

Change tc_dump_qdisc_root() to propagate tc_fill_qdisc() error to its callers.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/sched/sch_api.c | 39 ++++++++++++++++++---------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 32ccd4672083aa19340520155aeba6d8b6ff546c..322eab3bd2b1327af323c44333318bdd52c7ee52 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -976,7 +976,7 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid,
 out_nlmsg_trim:
 nla_put_failure:
 	nlmsg_trim(skb, b);
-	return -1;
+	return -EMSGSIZE;
 }
 
 static bool tc_qdisc_dump_ignore(struct Qdisc *q, bool dump_invisible)
@@ -1833,16 +1833,16 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
 		return 0;
 
 	q = root;
-	if (q_idx < s_q_idx) {
-		q_idx++;
-	} else {
-		if (!tc_qdisc_dump_ignore(q, dump_invisible) &&
-		    tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).portid,
-				  cb->nlh->nlmsg_seq, NLM_F_MULTI,
-				  RTM_NEWQDISC, NULL) <= 0)
-			goto done;
-		q_idx++;
+	if (!(q_idx < s_q_idx) &&
+	    !tc_qdisc_dump_ignore(q, dump_invisible)) {
+		ret = tc_fill_qdisc(skb, q, q->parent,
+				    NETLINK_CB(cb->skb).portid,
+				    cb->nlh->nlmsg_seq, NLM_F_MULTI,
+				    RTM_NEWQDISC, NULL);
+		if (ret < 0)
+			goto out;
 	}
+	q_idx++;
 
 	/* If dumping singletons, there is no qdisc_dev(root) and the singleton
 	 * itself has already been dumped.
@@ -1854,24 +1854,21 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
 		goto out;
 
 	hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
-		if (q_idx < s_q_idx) {
-			q_idx++;
-			continue;
+		if (!(q_idx < s_q_idx) &&
+		    !tc_qdisc_dump_ignore(q, dump_invisible)) {
+			ret = tc_fill_qdisc(skb, q, q->parent,
+					    NETLINK_CB(cb->skb).portid,
+					    cb->nlh->nlmsg_seq, NLM_F_MULTI,
+					    RTM_NEWQDISC, NULL);
+			if (ret < 0)
+				goto out;
 		}
-		if (!tc_qdisc_dump_ignore(q, dump_invisible) &&
-		    tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).portid,
-				  cb->nlh->nlmsg_seq, NLM_F_MULTI,
-				  RTM_NEWQDISC, NULL) <= 0)
-			goto done;
 		q_idx++;
 	}
 
 out:
 	*q_idx_p = q_idx;
 	return ret;
-done:
-	ret = -1;
-	goto out;
 }
 
 static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb)
-- 
2.54.0.545.g6539524ca2-goog