From 7ec1846242055cc68dc419ee4415b0d8b234ffd7 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 26 Jan 2022 13:01:19 +0900
Subject: [PATCH] network: tc: introduce order dependency of traffic control

---
 src/network/tc/qdisc.c  | 43 ++++++++++++++++++++++++++++++++++++++++-
 src/network/tc/qdisc.h  |  2 ++
 src/network/tc/tclass.c | 32 +++++++++++++++++++++++++++++-
 src/network/tc/tclass.h |  2 ++
 4 files changed, 77 insertions(+), 2 deletions(-)

diff --git a/src/network/tc/qdisc.c b/src/network/tc/qdisc.c
index 4fa1a6f5eac..7df6449de63 100644
--- a/src/network/tc/qdisc.c
+++ b/src/network/tc/qdisc.c
@@ -260,6 +260,44 @@ static void log_qdisc_debug(QDisc *qdisc, Link *link, const char *str) {
                        strna(qdisc_get_tca_kind(qdisc)));
 }
 
+int link_find_qdisc(Link *link, uint32_t handle, uint32_t parent, const char *kind, QDisc **ret) {
+        TrafficControl *tc;
+
+        assert(link);
+
+        handle = TC_H_MAJ(handle);
+
+        SET_FOREACH(tc, link->traffic_control) {
+                QDisc *qdisc;
+
+                if (tc->kind != TC_KIND_QDISC)
+                        continue;
+
+                qdisc = TC_TO_QDISC(tc);
+
+                if (qdisc->handle != handle)
+                        continue;
+
+                if (qdisc->parent != parent)
+                        continue;
+
+                if (qdisc->source == NETWORK_CONFIG_SOURCE_FOREIGN)
+                        continue;
+
+                if (!qdisc_exists(qdisc))
+                        continue;
+
+                if (kind && !streq_ptr(kind, qdisc_get_tca_kind(qdisc)))
+                        continue;
+
+                if (ret)
+                        *ret = qdisc;
+                return 0;
+        }
+
+        return -ENOENT;
+}
+
 static int qdisc_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
         int r;
 
@@ -326,7 +364,10 @@ int qdisc_is_ready_to_configure(Link *link, QDisc *qdisc) {
         assert(link);
         assert(qdisc);
 
-        return true;
+        if (IN_SET(qdisc->parent, TC_H_ROOT, TC_H_CLSACT)) /* TC_H_CLSACT == TC_H_INGRESS */
+                return true;
+
+        return link_find_tclass(link, qdisc->parent, NULL) >= 0;
 }
 
 int link_request_qdisc(Link *link, QDisc *qdisc) {
diff --git a/src/network/tc/qdisc.h b/src/network/tc/qdisc.h
index dc4156ad0af..1e4b72e271f 100644
--- a/src/network/tc/qdisc.h
+++ b/src/network/tc/qdisc.h
@@ -83,6 +83,8 @@ int qdisc_new_static(QDiscKind kind, Network *network, const char *filename, uns
 void qdisc_hash_func(const QDisc *qdic, struct siphash *state);
 int qdisc_compare_func(const QDisc *a, const QDisc *b);
 
+int link_find_qdisc(Link *link, uint32_t handle, uint32_t parent, const char *kind, QDisc **qdisc);
+
 int link_request_qdisc(Link *link, QDisc *qdisc);
 int qdisc_is_ready_to_configure(Link *link, QDisc *qdisc);
 int qdisc_configure(Link *link, QDisc *qdisc);
diff --git a/src/network/tc/tclass.c b/src/network/tc/tclass.c
index 2553caa76d9..903ff283362 100644
--- a/src/network/tc/tclass.c
+++ b/src/network/tc/tclass.c
@@ -213,6 +213,36 @@ static int tclass_dup(const TClass *src, TClass **ret) {
         return 0;
 }
 
+int link_find_tclass(Link *link, uint32_t classid, TClass **ret) {
+        TrafficControl *tc;
+
+        assert(link);
+
+        SET_FOREACH(tc, link->traffic_control) {
+                TClass *tclass;
+
+                if (tc->kind != TC_KIND_TCLASS)
+                        continue;
+
+                tclass = TC_TO_TCLASS(tc);
+
+                if (tclass->classid != classid)
+                        continue;
+
+                if (tclass->source == NETWORK_CONFIG_SOURCE_FOREIGN)
+                        continue;
+
+                if (!tclass_exists(tclass))
+                        continue;
+
+                if (ret)
+                        *ret = tclass;
+                return 0;
+        }
+
+        return -ENOENT;
+}
+
 static void log_tclass_debug(TClass *tclass, Link *link, const char *str) {
         _cleanup_free_ char *state = NULL;
 
@@ -297,7 +327,7 @@ int tclass_is_ready_to_configure(Link *link, TClass *tclass) {
         assert(link);
         assert(tclass);
 
-        return true;
+        return link_find_qdisc(link, tclass->classid, tclass->parent, tclass_get_tca_kind(tclass), NULL) >= 0;
 }
 
 int link_request_tclass(Link *link, TClass *tclass) {
diff --git a/src/network/tc/tclass.h b/src/network/tc/tclass.h
index 525630a87cb..6b12fba1e8b 100644
--- a/src/network/tc/tclass.h
+++ b/src/network/tc/tclass.h
@@ -65,6 +65,8 @@ int tclass_new_static(TClassKind kind, Network *network, const char *filename, u
 void tclass_hash_func(const TClass *tclass, struct siphash *state);
 int tclass_compare_func(const TClass *a, const TClass *b);
 
+int link_find_tclass(Link *link, uint32_t classid, TClass **ret);
+
 int link_request_tclass(Link *link, TClass *tclass);
 int tclass_is_ready_to_configure(Link *link, TClass *tclass);
 int tclass_configure(Link *link, TClass *tclass);