[RFC,3/5] net: Add & modify tracepoints to skb FCLONE_SCRATCH paths

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index e04fa48..77e3605 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2540,26 +2540,7 @@  extern unsigned int skb_make_fclone_scratch(struct sk_buff *skb);
 /*
  * Allocates an skb out of our scratch space
  */
-static inline struct sk_buff *alloc_fscratch_skb(struct sk_buff *skb)
-{
-	struct skb_scr_control *sctl = skb_get_scratch_control(skb);
-	struct sk_buff *sskb;
-
-	BUG_ON(skb->fclone != SKB_FCLONE_SCRATCH);
-	BUG_ON(!sctl);
-	BUG_ON(sctl->owner != skb);
-	if (skb_queue_empty(&sctl->scr_skbs))
-		return NULL;
-
-	sskb = __skb_dequeue(&sctl->scr_skbs);
-
-	/*
-	 * Mark us as a scratch skb, so we get properly kfree-ed
-	 */
-	sskb->fclone = SKB_FCLONE_SCRATCH;
-
-	return sskb;
-}
+extern struct sk_buff *alloc_fscratch_skb(struct sk_buff *skb);
 
 #endif	/* __KERNEL__ */
 #endif	/* _LINUX_SKBUFF_H */
diff --git a/include/trace/events/napi.h b/include/trace/events/napi.h
index 8fe1e93..5af5675 100644
--- a/include/trace/events/napi.h
+++ b/include/trace/events/napi.h
@@ -7,6 +7,7 @@ 
 #include <linux/netdevice.h>
 #include <linux/tracepoint.h>
 #include <linux/ftrace.h>
+#include <linux/kernel_stat.h>
 
 #define NO_DEV "(no_device)"
 
@@ -30,6 +31,46 @@  TRACE_EVENT(napi_poll,
 		__entry->napi, __get_str(dev_name))
 );
 
+TRACE_EVENT(napi_schedule,
+
+	TP_PROTO(struct napi_struct *napi),
+
+	TP_ARGS(napi),
+
+	TP_STRUCT__entry(
+		__field(	struct napi_struct *,	napi)
+		__string(	dev_name, napi->dev ? napi->dev->name : NO_DEV)
+	),
+
+	TP_fast_assign(
+		__entry->napi = napi;
+		__assign_str(dev_name, napi->dev ? napi->dev->name : NO_DEV);
+	),
+
+	TP_printk("napi schedule on napi struct %p for device %s",
+		__entry->napi, __get_str(dev_name))
+);
+
+TRACE_EVENT(napi_complete,
+
+	TP_PROTO(struct napi_struct *napi),
+
+	TP_ARGS(napi),
+
+	TP_STRUCT__entry(
+		__field(	struct napi_struct *,	napi)
+		__string(	dev_name, napi->dev ? napi->dev->name : NO_DEV)
+	),
+
+	TP_fast_assign(
+		__entry->napi = napi;
+		__assign_str(dev_name, napi->dev ? napi->dev->name : NO_DEV);
+	),
+
+	TP_printk("napi complete on napi struct %p for device %s",
+		__entry->napi, __get_str(dev_name))
+);
+
 #undef NO_DEV
 
 #endif /* _TRACE_NAPI_H_ */
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 0c68ae22..3b83438 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -69,6 +69,47 @@  TRACE_EVENT(skb_copy_datagram_iovec,
 	TP_printk("skbaddr=%p len=%d", __entry->skbaddr, __entry->len)
 );
 
+TRACE_EVENT(skb_make_fclone_scratch,
+
+	TP_PROTO(struct sk_buff *skb, int count),
+
+	TP_ARGS(skb, count),
+
+	TP_STRUCT__entry(
+		__field(	const struct sk_buff *,	skb)
+		__string(	name, skb->dev ? skb->dev->name : "unknown")
+		__field(	int,			fccount)
+	),
+
+	TP_fast_assign(
+		__entry->skb = skb;
+		__assign_str(name, skb->dev ? skb->dev->name : "unknown");
+		__entry->fccount = count;
+	),
+
+	TP_printk("skb= %p, dev=%s, count=%d", __entry->skb,
+		  __get_str(name), __entry->fccount)
+);
+
+TRACE_EVENT(alloc_fscratch_skb,
+
+	TP_PROTO(const struct sk_buff *parent, const struct sk_buff *child),
+
+	TP_ARGS(parent, child),
+
+	TP_STRUCT__entry(
+		__field(	const struct sk_buff *, parent)
+		__field(	const struct sk_buff *, child)
+	),
+
+	TP_fast_assign(
+		__entry->parent = parent;
+		__entry->child = child;
+	),
+
+	TP_printk("parent=%p, child=%p", __entry->parent, __entry->child)
+);
+
 #endif /* _TRACE_SKB_H */
 
 /* This part must be outside protection */
diff --git a/net/core/dev.c b/net/core/dev.c
index b7ba81a..1af4c02 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2579,6 +2579,7 @@  int weight_p __read_mostly = 64;            /* old backlog weight */
 static inline void ____napi_schedule(struct softnet_data *sd,
 				     struct napi_struct *napi)
 {
+	trace_napi_schedule(napi);
 	list_add_tail(&napi->poll_list, &sd->poll_list);
 	__raise_softirq_irqoff(NET_RX_SOFTIRQ);
 }
@@ -3829,6 +3830,7 @@  void __napi_complete(struct napi_struct *n)
 	BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state));
 	BUG_ON(n->gro_list);
 
+	trace_napi_complete(n);
 	list_del(&n->poll_list);
 	smp_mb__before_clear_bit();
 	clear_bit(NAPI_STATE_SCHED, &n->state);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 6fdf1a7..0347446 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3221,6 +3221,30 @@  void __skb_warn_lro_forwarding(const struct sk_buff *skb)
 }
 EXPORT_SYMBOL(__skb_warn_lro_forwarding);
 
+/*
+ * Allocates an skb out of our scratch space
+ */
+struct sk_buff *alloc_fscratch_skb(struct sk_buff *skb)
+{
+	struct skb_scr_control *sctl = skb_get_scratch_control(skb);
+	struct sk_buff *sskb = NULL;
+
+	BUG_ON(skb->fclone != SKB_FCLONE_SCRATCH);
+	BUG_ON(!sctl);
+	BUG_ON(sctl->owner != skb);
+
+	sskb = __skb_dequeue(&sctl->scr_skbs);
+
+	/*
+	 * Mark us as a scratch skb, so we get properly kfree-ed
+	 */
+	sskb->fclone = SKB_FCLONE_SCRATCH;
+
+	trace_alloc_fscratch_skb(skb, sskb);
+	return sskb;
+}
+EXPORT_SYMBOL(alloc_fscratch_skb);
+
 unsigned int skb_make_fclone_scratch(struct sk_buff *skb)
 {
 	size_t bufsz, totsz, scrsz, tmpsz;
@@ -3228,15 +3252,16 @@  unsigned int skb_make_fclone_scratch(struct sk_buff *skb)
 	struct sk_buff *scr_skb;
 	struct skb_shared_info *old_info;
 	bool format_tail = false;
+	int fclone_count = 0;
 
 	if (skb_shared(skb))
-		return 0;
+		goto out;
 
 	/*
 	 * Cant do scratch space on fcloned skbs
 	 */
 	if (skb->fclone)
-		return 0;
+		goto out;
 
 	if ((skb->end - skb->tail) > sizeof(struct skb_shared_info)) {
 		old_info = skb_shinfo(skb);
@@ -3257,7 +3282,7 @@  unsigned int skb_make_fclone_scratch(struct sk_buff *skb)
 		 sizeof(struct skb_shared_info);
 
 	if ((bufsz + sizeof(struct skb_scr_control)) >= totsz)
-		return 0;
+		goto out;
 
 	/*
 	 * And this is the leftover area, minus sizeof(int) to store the number
@@ -3278,6 +3303,10 @@  unsigned int skb_make_fclone_scratch(struct sk_buff *skb)
 
 	skb->fclone = SKB_FCLONE_SCRATCH;
 
-	return skb_queue_len(&sctl->scr_skbs);
+	fclone_count = skb_queue_len(&sctl->scr_skbs);
+out:
+	trace_skb_make_fclone_scratch(skb, fclone_count);
+	return fclone_count;
 
 }
+EXPORT_SYMBOL(skb_make_fclone_scratch);