From 70713dddf3d25a02d1952f8c5d2688c986d2f2fb Mon Sep 17 00:00:00 2001 From: Qitao Xu Date: Wed, 14 Jul 2021 23:03:24 -0700 Subject: [PATCH] net_sched: introduce tracepoint trace_qdisc_enqueue() Tracepoint trace_qdisc_enqueue() is introduced to trace skb at the entrance of TC layer on TX side. This is similar to trace_qdisc_dequeue(): 1. For both we only trace successful cases. The failure cases can be traced via trace_kfree_skb(). 2. They are called at entrance or exit of TC layer, not for each ->enqueue() or ->dequeue(). This is intentional, because we want to make trace_qdisc_enqueue() symmetric to trace_qdisc_dequeue(), which is easier to use. The return value of qdisc_enqueue() is not interesting here, we have Qdisc's drop packets in ->dequeue(), it is impossible to trace them even if we have the return value, the only way to trace them is tracing kfree_skb(). We only add information we need to trace ring buffer. If any other information is needed, it is easy to extend it without breaking ABI, see commit 3dd344ea84e1 ("net: tracepoint: exposing sk_family in all tcp:tracepoints"). Reviewed-by: Cong Wang Signed-off-by: Qitao Xu Signed-off-by: David S. Miller --- include/trace/events/qdisc.h | 26 ++++++++++++++++++++++++++ net/core/dev.c | 20 ++++++++++++++++---- 2 files changed, 42 insertions(+), 4 deletions(-) diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h index 5820955..c3006c6 100644 --- a/include/trace/events/qdisc.h +++ b/include/trace/events/qdisc.h @@ -46,6 +46,32 @@ TRACE_EVENT(qdisc_dequeue, __entry->txq_state, __entry->packets, __entry->skbaddr ) ); +TRACE_EVENT(qdisc_enqueue, + + TP_PROTO(struct Qdisc *qdisc, const struct netdev_queue *txq, struct sk_buff *skb), + + TP_ARGS(qdisc, txq, skb), + + TP_STRUCT__entry( + __field(struct Qdisc *, qdisc) + __field(void *, skbaddr) + __field(int, ifindex) + __field(u32, handle) + __field(u32, parent) + ), + + TP_fast_assign( + __entry->qdisc = qdisc; + __entry->skbaddr = skb; + __entry->ifindex = txq->dev ? txq->dev->ifindex : 0; + __entry->handle = qdisc->handle; + __entry->parent = qdisc->parent; + ), + + TP_printk("enqueue ifindex=%d qdisc handle=0x%X parent=0x%X skbaddr=%px", + __entry->ifindex, __entry->handle, __entry->parent, __entry->skbaddr) +); + TRACE_EVENT(qdisc_reset, TP_PROTO(struct Qdisc *q), diff --git a/net/core/dev.c b/net/core/dev.c index 64b21f0..7aeefc4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -131,6 +131,7 @@ #include #include #include +#include #include #include #include @@ -3844,6 +3845,18 @@ static void qdisc_pkt_len_init(struct sk_buff *skb) } } +static int dev_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *q, + struct sk_buff **to_free, + struct netdev_queue *txq) +{ + int rc; + + rc = q->enqueue(skb, q, to_free) & NET_XMIT_MASK; + if (rc == NET_XMIT_SUCCESS) + trace_qdisc_enqueue(q, txq, skb); + return rc; +} + static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, struct net_device *dev, struct netdev_queue *txq) @@ -3862,8 +3875,7 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, * of q->seqlock to protect from racing with requeuing. */ if (unlikely(!nolock_qdisc_is_empty(q))) { - rc = q->enqueue(skb, q, &to_free) & - NET_XMIT_MASK; + rc = dev_qdisc_enqueue(skb, q, &to_free, txq); __qdisc_run(q); qdisc_run_end(q); @@ -3879,7 +3891,7 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, return NET_XMIT_SUCCESS; } - rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK; + rc = dev_qdisc_enqueue(skb, q, &to_free, txq); qdisc_run(q); no_lock_out: @@ -3923,7 +3935,7 @@ no_lock_out: qdisc_run_end(q); rc = NET_XMIT_SUCCESS; } else { - rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK; + rc = dev_qdisc_enqueue(skb, q, &to_free, txq); if (qdisc_run_begin(q)) { if (unlikely(contended)) { spin_unlock(&q->busylock); -- 2.7.4