net/sched: sch_cake: Add cake_mq qdisc for using cake on mq devices

Add a cake_mq qdisc which installs cake instances on each hardware
queue on a multi-queue device.

This is just a copy of sch_mq that installs cake instead of the default
qdisc on each queue. Subsequent commits will add sharing of the config
between cake instances, as well as a multi-queue aware shaper algorithm.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://patch.msgid.link/20260109-mq-cake-sub-qdisc-v8-3-8d613fece5d8@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index 8171674b160d03c09a5c2ce540a7a99b1264cc9e..2671481d8e011dc569b38574c3db4f5a1453db9a 100644 (file)
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -67,6 +67,7 @@
 #include <linux/if_vlan.h>
 #include <net/gso.h>
 #include <net/pkt_sched.h>
+#include <net/sch_priv.h>
 #include <net/pkt_cls.h>
 #include <net/tcp.h>
 #include <net/flow_dissector.h>
@@ -3157,14 +3158,89 @@ static struct Qdisc_ops cake_qdisc_ops __read_mostly = {
 };
 MODULE_ALIAS_NET_SCH("cake");
 
+struct cake_mq_sched {
+       struct mq_sched mq_priv; /* must be first */
+};
+
+static void cake_mq_destroy(struct Qdisc *sch)
+{
+       mq_destroy_common(sch);
+}
+
+static int cake_mq_init(struct Qdisc *sch, struct nlattr *opt,
+                       struct netlink_ext_ack *extack)
+{
+       int ret;
+
+       ret = mq_init_common(sch, opt, extack, &cake_qdisc_ops);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
+static int cake_mq_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+       mq_dump_common(sch, skb);
+       return 0;
+}
+
+static int cake_mq_change(struct Qdisc *sch, struct nlattr *opt,
+                         struct netlink_ext_ack *extack)
+{
+       return -EOPNOTSUPP;
+}
+
+static int cake_mq_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
+                        struct Qdisc **old, struct netlink_ext_ack *extack)
+{
+       NL_SET_ERR_MSG(extack, "can't replace cake_mq sub-qdiscs");
+       return -EOPNOTSUPP;
+}
+
+static const struct Qdisc_class_ops cake_mq_class_ops = {
+       .select_queue   = mq_select_queue,
+       .graft          = cake_mq_graft,
+       .leaf           = mq_leaf,
+       .find           = mq_find,
+       .walk           = mq_walk,
+       .dump           = mq_dump_class,
+       .dump_stats     = mq_dump_class_stats,
+};
+
+static struct Qdisc_ops cake_mq_qdisc_ops __read_mostly = {
+       .cl_ops         =       &cake_mq_class_ops,
+       .id             =       "cake_mq",
+       .priv_size      =       sizeof(struct cake_mq_sched),
+       .init           =       cake_mq_init,
+       .destroy        =       cake_mq_destroy,
+       .attach         =       mq_attach,
+       .change         =       cake_mq_change,
+       .change_real_num_tx = mq_change_real_num_tx,
+       .dump           =       cake_mq_dump,
+       .owner          =       THIS_MODULE,
+};
+MODULE_ALIAS_NET_SCH("cake_mq");
+
 static int __init cake_module_init(void)
 {
-       return register_qdisc(&cake_qdisc_ops);
+       int ret;
+
+       ret = register_qdisc(&cake_qdisc_ops);
+       if (ret)
+               return ret;
+
+       ret = register_qdisc(&cake_mq_qdisc_ops);
+       if (ret)
+               unregister_qdisc(&cake_qdisc_ops);
+
+       return ret;
 }
 
 static void __exit cake_module_exit(void)
 {
        unregister_qdisc(&cake_qdisc_ops);
+       unregister_qdisc(&cake_mq_qdisc_ops);
 }
 
 module_init(cake_module_init)
@@ -3172,3 +3248,4 @@ module_exit(cake_module_exit)
 MODULE_AUTHOR("Jonathan Morton");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_DESCRIPTION("The CAKE shaper.");
+MODULE_IMPORT_NS("NET_SCHED_INTERNAL");