net_sched: add tracepoints for qdisc_reset() and qdisc_destroy()

Add two tracepoints for qdisc_reset() and qdisc_destroy() to track
qdisc resetting and destroying.

Sample output:

  tc-756   [000] ...3   138.355662: qdisc_reset: dev=ens3 kind=pfifo_fast parent=ffff:ffff handle=0:0
  tc-756   [000] ...1   138.355720: qdisc_reset: dev=ens3 kind=pfifo_fast parent=ffff:ffff handle=0:0
  tc-756   [000] ...1   138.355867: qdisc_reset: dev=ens3 kind=pfifo_fast parent=ffff:ffff handle=0:0
  tc-756   [000] ...1   138.355930: qdisc_destroy: dev=ens3 kind=pfifo_fast parent=ffff:ffff handle=0:0
  tc-757   [000] ...2   143.073780: qdisc_reset: dev=ens3 kind=fq_codel parent=ffff:ffff handle=8001:0
  tc-757   [000] ...1   143.073878: qdisc_reset: dev=ens3 kind=fq_codel parent=ffff:ffff handle=8001:0
  tc-757   [000] ...1   143.074114: qdisc_reset: dev=ens3 kind=fq_codel parent=ffff:ffff handle=8001:0
  tc-757   [000] ...1   143.074228: qdisc_destroy: dev=ens3 kind=fq_codel parent=ffff:ffff handle=8001:0

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/trace/events/qdisc.h

@@ -8,6 +8,8 @@
 #include <linux/netdevice.h>
 #include <linux/tracepoint.h>
 #include <linux/ftrace.h>
+#include <linux/pkt_sched.h>
+#include <net/sch_generic.h>
 
 TRACE_EVENT(qdisc_dequeue,
 
@@ -44,6 +46,56 @@ TRACE_EVENT(qdisc_dequeue,
 		  __entry->txq_state, __entry->packets, __entry->skbaddr )
 );
 
+TRACE_EVENT(qdisc_reset,
+
+	TP_PROTO(struct Qdisc *q),
+
+	TP_ARGS(q),
+
+	TP_STRUCT__entry(
+		__string(	dev,		qdisc_dev(q)	)
+		__string(	kind,		q->ops->id	)
+		__field(	u32,		parent		)
+		__field(	u32,		handle		)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev, qdisc_dev(q));
+		__assign_str(kind, q->ops->id);
+		__entry->parent = q->parent;
+		__entry->handle = q->handle;
+	),
+
+	TP_printk("dev=%s kind=%s parent=%x:%x handle=%x:%x", __get_str(dev),
+		  __get_str(kind), TC_H_MAJ(__entry->parent) >> 16, TC_H_MIN(__entry->parent),
+		  TC_H_MAJ(__entry->handle) >> 16, TC_H_MIN(__entry->handle))
+);
+
+TRACE_EVENT(qdisc_destroy,
+
+	TP_PROTO(struct Qdisc *q),
+
+	TP_ARGS(q),
+
+	TP_STRUCT__entry(
+		__string(	dev,		qdisc_dev(q)	)
+		__string(	kind,		q->ops->id	)
+		__field(	u32,		parent		)
+		__field(	u32,		handle		)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev, qdisc_dev(q));
+		__assign_str(kind, q->ops->id);
+		__entry->parent = q->parent;
+		__entry->handle = q->handle;
+	),
+
+	TP_printk("dev=%s kind=%s parent=%x:%x handle=%x:%x", __get_str(dev),
+		  __get_str(kind), TC_H_MAJ(__entry->parent) >> 16, TC_H_MIN(__entry->parent),
+		  TC_H_MAJ(__entry->handle) >> 16, TC_H_MIN(__entry->handle))
+);
+
 #endif /* _TRACE_QDISC_H */
 
 /* This part must be outside protection */

net/sched/sch_generic.c

@@ -911,6 +911,8 @@ void qdisc_reset(struct Qdisc *qdisc)
 	const struct Qdisc_ops *ops = qdisc->ops;
 	struct sk_buff *skb, *tmp;
 
+	trace_qdisc_reset(qdisc);
+
 	if (ops->reset)
 		ops->reset(qdisc);
 
@@ -965,6 +967,8 @@ static void qdisc_destroy(struct Qdisc *qdisc)
 	module_put(ops->owner);
 	dev_put(qdisc_dev(qdisc));
 
+	trace_qdisc_destroy(qdisc);
+
 	call_rcu(&qdisc->rcu, qdisc_free_cb);
 }