net/sched: taprio: replace safety precautions with comments

The WARN_ON_ONCE() checks introduced in commit 13511704f8d7 ("net:
taprio offload: enforce qdisc to netdev queue mapping") take a small
toll on performance, but otherwise, the conditions are never expected to
happen. Replace them with comments, such that the information is still
conveyed to developers.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 2552f62..b72c373 100644 (file)
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -432,6 +432,9 @@ static int taprio_enqueue_one(struct sk_buff *skb, struct Qdisc *sch,
        return qdisc_enqueue(skb, child, to_free);
 }
 
+/* Will not be called in the full offload case, since the TX queues are
+ * attached to the Qdisc created using qdisc_create_dflt()
+ */
 static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
                          struct sk_buff **to_free)
 {
@@ -439,11 +442,6 @@ static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
        struct Qdisc *child;
        int queue;
 
-       if (unlikely(FULL_OFFLOAD_IS_ENABLED(q->flags))) {
-               WARN_ONCE(1, "Trying to enqueue skb into the root of a taprio qdisc configured with full offload\n");
-               return qdisc_drop(skb, sch, to_free);
-       }
-
        queue = skb_get_queue_mapping(skb);
 
        child = q->qdiscs[queue];
@@ -489,6 +487,9 @@ static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
        return taprio_enqueue_one(skb, sch, child, to_free);
 }
 
+/* Will not be called in the full offload case, since the TX queues are
+ * attached to the Qdisc created using qdisc_create_dflt()
+ */
 static struct sk_buff *taprio_peek(struct Qdisc *sch)
 {
        struct taprio_sched *q = qdisc_priv(sch);
@@ -498,11 +499,6 @@ static struct sk_buff *taprio_peek(struct Qdisc *sch)
        u32 gate_mask;
        int i;
 
-       if (unlikely(FULL_OFFLOAD_IS_ENABLED(q->flags))) {
-               WARN_ONCE(1, "Trying to peek into the root of a taprio qdisc configured with full offload\n");
-               return NULL;
-       }
-
        rcu_read_lock();
        entry = rcu_dereference(q->current_entry);
        gate_mask = entry ? entry->gate_mask : TAPRIO_ALL_GATES_OPEN;
@@ -545,6 +541,9 @@ static void taprio_set_budget(struct taprio_sched *q, struct sched_entry *entry)
                             atomic64_read(&q->picos_per_byte)));
 }
 
+/* Will not be called in the full offload case, since the TX queues are
+ * attached to the Qdisc created using qdisc_create_dflt()
+ */
 static struct sk_buff *taprio_dequeue(struct Qdisc *sch)
 {
        struct taprio_sched *q = qdisc_priv(sch);
@@ -554,11 +553,6 @@ static struct sk_buff *taprio_dequeue(struct Qdisc *sch)
        u32 gate_mask;
        int i;
 
-       if (unlikely(FULL_OFFLOAD_IS_ENABLED(q->flags))) {
-               WARN_ONCE(1, "Trying to dequeue from the root of a taprio qdisc configured with full offload\n");
-               return NULL;
-       }
-
        rcu_read_lock();
        entry = rcu_dereference(q->current_entry);
        /* if there's no entry, it means that the schedule didn't