napi: Convert trace_napi_poll to TRACE_EVENT

This patch converts trace_napi_poll from DECLARE_EVENT to TRACE_EVENT
to improve the usability of napi_poll tracepoint.

<idle>-0 [001] 241302.750777: napi_poll: napi poll on napi struct f6acc480 for device eth3
<idle>-0 [000] 241302.852389: napi_poll: napi poll on napi struct f5d0d70c for device eth1

The original patch is below:
http://marc.info/?l=linux-kernel&m=126021713809450&w=2

[ [e-mail]: And add a fix by Steven Rostedt:
http://marc.info/?l=linux-kernel&m=126150506519173&w=2 ]

Signed-off-by: Neil Horman <[e-mail]>
Acked-by: David S. Miller <[e-mail]>
Acked-by: Neil Horman <[e-mail]>
Cc: Mathieu Desnoyers <[e-mail]>
Cc: Kaneshige Kenji <[e-mail]>
Cc: Izumo Taku <[e-mail]>
Cc: Kosaki Motohiro <[e-mail]>
Cc: Lai Jiangshan <[e-mail]>
Cc: Scott Mcmillan <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Eric Dumazet <[e-mail]>
LKML-Reference: <[e-mail]>
Signed-off-by: Koki Sanagi <[e-mail]>
Signed-off-by: Frederic Weisbecker <[e-mail]>

include/trace/events/napi.h

···
 
 #include <linux/netdevice.h>
 #include <linux/tracepoint.h>
+#include <linux/ftrace.h>
 
-DECLARE_TRACE(napi_poll,
+#define NO_DEV "(no_device)"
+
+TRACE_EVENT(napi_poll,
+
 	TP_PROTO(struct napi_struct *napi),
-	TP_ARGS(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 poll on napi struct %p for device %s",
+		__entry->napi, __get_str(dev_name))
+);
+
+#undef NO_DEV
 
 #endif /* _TRACE_NAPI_H_ */