[PATCH net-next] net/sched: Add precise drop reason for pfifo_fast queue overflows

[fan.yu9]

From: Fan Yu <fan.yu9@xxxxxxxxxx>

Currently, packets dropped by pfifo_fast due to queue overflow are
marked with a generic SKB_DROP_REASON_QDISC_DROP in __dev_xmit_skb().

This patch adds explicit drop reason SKB_DROP_REASON_QDISC_OVERLIMIT
for queue-full cases, providing better distinction from other qdisc drops.

Signed-off-by: Fan Yu <fan.yu9@xxxxxxxxxx>
---
 net/sched/sch_generic.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 16afb834fe4a..1e008a228ebd 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -740,6 +740,8 @@ static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 	err = skb_array_produce(q, skb);

 	if (unlikely(err)) {
+		tcf_set_drop_reason(skb, SKB_DROP_REASON_QDISC_OVERLIMIT);
+
 		if (qdisc_is_percpu_stats(qdisc))
 			return qdisc_drop_cpu(skb, qdisc, to_free);
 		else
-- 
2.25.1