[RFC PATCH v9 07/11] bpf: net_sched: Allow more optional operators in Qdisc_ops

[Amery Hung <ameryhung@xxxxxxxxx>]

From: Amery Hung <ameryhung@xxxxxxxxx>

So far, init, reset, and destroy are implemented by bpf qdisc infra as
fixed operators that manipulate the watchdog according to the occasion.
This patch allows users to implement these three operators to perform
desired work alongside the predefined ones.

Signed-off-by: Amery Hung <amery.hung@xxxxxxxxxxxxx>
---
 include/net/sch_generic.h |  4 ++++
 net/sched/bpf_qdisc.c     | 23 +++++++----------------
 net/sched/sch_api.c       | 11 +++++++++++
 net/sched/sch_generic.c   |  8 ++++++++
 4 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 214ed2e34faa..1ab9e91281c0 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -1359,4 +1359,8 @@ static inline void qdisc_synchronize(const struct Qdisc *q)
 		msleep(1);
 }
 
+int bpf_qdisc_init_pre_op(struct Qdisc *sch, struct nlattr *opt, struct netlink_ext_ack *extack);
+void bpf_qdisc_destroy_post_op(struct Qdisc *sch);
+void bpf_qdisc_reset_post_op(struct Qdisc *sch);
+
 #endif
diff --git a/net/sched/bpf_qdisc.c b/net/sched/bpf_qdisc.c
index eff7559aa346..0273b3f8f230 100644
--- a/net/sched/bpf_qdisc.c
+++ b/net/sched/bpf_qdisc.c
@@ -9,9 +9,6 @@
 static struct bpf_struct_ops bpf_Qdisc_ops;
 
 static u32 unsupported_ops[] = {
-	offsetof(struct Qdisc_ops, init),
-	offsetof(struct Qdisc_ops, reset),
-	offsetof(struct Qdisc_ops, destroy),
 	offsetof(struct Qdisc_ops, change),
 	offsetof(struct Qdisc_ops, attach),
 	offsetof(struct Qdisc_ops, change_real_num_tx),
@@ -36,28 +33,31 @@ static int bpf_qdisc_init(struct btf *btf)
 	return 0;
 }
 
-static int bpf_qdisc_init_op(struct Qdisc *sch, struct nlattr *opt,
-			     struct netlink_ext_ack *extack)
+int bpf_qdisc_init_pre_op(struct Qdisc *sch, struct nlattr *opt,
+			  struct netlink_ext_ack *extack)
 {
 	struct bpf_sched_data *q = qdisc_priv(sch);
 
 	qdisc_watchdog_init(&q->watchdog, sch);
 	return 0;
 }
+EXPORT_SYMBOL(bpf_qdisc_init_pre_op);
 
-static void bpf_qdisc_reset_op(struct Qdisc *sch)
+void bpf_qdisc_reset_post_op(struct Qdisc *sch)
 {
 	struct bpf_sched_data *q = qdisc_priv(sch);
 
 	qdisc_watchdog_cancel(&q->watchdog);
 }
+EXPORT_SYMBOL(bpf_qdisc_reset_post_op);
 
-static void bpf_qdisc_destroy_op(struct Qdisc *sch)
+void bpf_qdisc_destroy_post_op(struct Qdisc *sch)
 {
 	struct bpf_sched_data *q = qdisc_priv(sch);
 
 	qdisc_watchdog_cancel(&q->watchdog);
 }
+EXPORT_SYMBOL(bpf_qdisc_destroy_post_op);
 
 static const struct bpf_func_proto *
 bpf_qdisc_get_func_proto(enum bpf_func_id func_id,
@@ -235,15 +235,6 @@ static int bpf_qdisc_init_member(const struct btf_type *t,
 			return -EINVAL;
 		qdisc_ops->static_flags = TCQ_F_BPF;
 		return 1;
-	case offsetof(struct Qdisc_ops, init):
-		qdisc_ops->init = bpf_qdisc_init_op;
-		return 1;
-	case offsetof(struct Qdisc_ops, reset):
-		qdisc_ops->reset = bpf_qdisc_reset_op;
-		return 1;
-	case offsetof(struct Qdisc_ops, destroy):
-		qdisc_ops->destroy = bpf_qdisc_destroy_op;
-		return 1;
 	case offsetof(struct Qdisc_ops, peek):
 		if (!uqdisc_ops->peek)
 			qdisc_ops->peek = qdisc_peek_dequeued;
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 5064b6d2d1ec..6379edf94f69 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1352,6 +1352,13 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 		rcu_assign_pointer(sch->stab, stab);
 	}
 
+#ifdef CONFIG_NET_SCH_BPF
+	if (sch->flags & TCQ_F_BPF) {
+		err = bpf_qdisc_init_pre_op(sch, tca[TCA_OPTIONS], extack);
+		if (err != 0)
+			goto err_out4;
+	}
+#endif
 	if (ops->init) {
 		err = ops->init(sch, tca[TCA_OPTIONS], extack);
 		if (err != 0)
@@ -1388,6 +1395,10 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 	 */
 	if (ops->destroy)
 		ops->destroy(sch);
+#ifdef CONFIG_NET_SCH_BPF
+	if (sch->flags & TCQ_F_BPF)
+		bpf_qdisc_destroy_post_op(sch);
+#endif
 	qdisc_put_stab(rtnl_dereference(sch->stab));
 err_out3:
 	lockdep_unregister_key(&sch->root_lock_key);
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 76e4a6efd17c..0906d8a9f35d 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -1033,6 +1033,10 @@ void qdisc_reset(struct Qdisc *qdisc)
 
 	if (ops->reset)
 		ops->reset(qdisc);
+#ifdef CONFIG_NET_SCH_BPF
+	if (qdisc->flags & TCQ_F_BPF)
+		bpf_qdisc_reset_post_op(qdisc);
+#endif
 
 	__skb_queue_purge(&qdisc->gso_skb);
 	__skb_queue_purge(&qdisc->skb_bad_txq);
@@ -1076,6 +1080,10 @@ static void __qdisc_destroy(struct Qdisc *qdisc)
 
 	if (ops->destroy)
 		ops->destroy(qdisc);
+#ifdef CONFIG_NET_SCH_BPF
+	if (qdisc->flags & TCQ_F_BPF)
+		bpf_qdisc_destroy_post_op(qdisc);
+#endif
 
 	lockdep_unregister_key(&qdisc->root_lock_key);
 	bpf_module_put(ops, ops->owner);
-- 
2.20.1