[PATCH RFC net-next 3/6] net_sched: sch_fq: multiple release time support

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

From: Willem de Bruijn <willemb@google.com>

Optionally segment skbs on FQ enqueue, to later send segments at
their individual delivery time.

Segmentation on enqueue is new for FQ, but already happens in TBF,
CAKE and netem.

This slow patch should probably be behind a static_branch.

Signed-off-by: Willem de Bruijn <willemb@google.com>
---
 net/sched/sch_fq.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 8f06a808c59a..a5e2c35bb557 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -439,8 +439,8 @@ static bool fq_packet_beyond_horizon(const struct sk_buff *skb,
 	return unlikely((s64)skb->tstamp > (s64)(q->ktime_cache + q->horizon));
 }
 
-static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
-		      struct sk_buff **to_free)
+static int __fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+			struct sk_buff **to_free)
 {
 	struct fq_sched_data *q = qdisc_priv(sch);
 	struct fq_flow *f;
@@ -496,6 +496,35 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 	return NET_XMIT_SUCCESS;
 }
 
+static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+		      struct sk_buff **to_free)
+{
+	struct sk_buff *segs, *next;
+	int ret;
+
+	if (likely(!skb_is_gso(skb) || !skb->sk ||
+		   !skb->sk->sk_txtime_multi_release))
+		return __fq_enqueue(skb, sch, to_free);
+
+	segs = skb_gso_segment_txtime(skb);
+	if (IS_ERR(segs))
+		return qdisc_drop(skb, sch, to_free);
+	if (!segs)
+		return __fq_enqueue(skb, sch, to_free);
+
+	consume_skb(skb);
+
+	ret = NET_XMIT_DROP;
+	skb_list_walk_safe(segs, segs, next) {
+		skb_mark_not_on_list(segs);
+		qdisc_skb_cb(segs)->pkt_len = segs->len;
+		if (__fq_enqueue(segs, sch, to_free) == NET_XMIT_SUCCESS)
+			ret = NET_XMIT_SUCCESS;
+	}
+
+	return ret;
+}
+
 static void fq_check_throttled(struct fq_sched_data *q, u64 now)
 {
 	unsigned long sample;
-- 
2.27.0.278.ge193c7cf3a9-goog