[PATCH v2 1/2] tracing/events: make __string() more general

[Li Zefan <lizf@cn.fujitsu.com>]

This changes __string(..., src) to __string(..., len), thus makes it more
general, and then block TRACE_EVENT() can use it.

Also introduce __fetch_str(), which is used in TP_assign() and returns
the address of the string, while __get_str() is used in TP_print().

[ Impact: TRACE_EVENT api change ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 include/trace/events/irq.h     |   12 ++++++------
 include/trace/events/lockdep.h |    8 ++++----
 include/trace/ftrace.h         |   21 +++++++++++++--------
 3 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
index 32a9f7e..ce2b939 100644
--- a/include/trace/events/irq.h
+++ b/include/trace/events/irq.h
@@ -25,8 +25,8 @@ TRACE_EVENT(irq_handler_entry,
 	TP_ARGS(irq, action),
 
 	TP_STRUCT__entry(
-		__field(	int,	irq		)
-		__string(	name,	action->name	)
+		__field(	int,	irq			)
+		__string(	name,	strlen(action->name)	)
 	),
 
 	TP_fast_assign(
@@ -86,8 +86,8 @@ TRACE_EVENT(softirq_entry,
 	TP_ARGS(h, vec),
 
 	TP_STRUCT__entry(
-		__field(	int,	vec			)
-		__string(	name,	softirq_to_name[h-vec]	)
+		__field(	int,	vec				)
+		__string(	name,	strlen(softirq_to_name[h-vec])	)
 	),
 
 	TP_fast_assign(
@@ -116,8 +116,8 @@ TRACE_EVENT(softirq_exit,
 	TP_ARGS(h, vec),
 
 	TP_STRUCT__entry(
-		__field(	int,	vec			)
-		__string(	name,	softirq_to_name[h-vec]	)
+		__field(	int,	vec				)
+		__string(	name,	strlen(softirq_to_name[h-vec])	)
 	),
 
 	TP_fast_assign(
diff --git a/include/trace/events/lockdep.h b/include/trace/events/lockdep.h
index 0e956c9..e6218fd 100644
--- a/include/trace/events/lockdep.h
+++ b/include/trace/events/lockdep.h
@@ -19,7 +19,7 @@ TRACE_EVENT(lock_acquire,
 
 	TP_STRUCT__entry(
 		__field(unsigned int, flags)
-		__string(name, lock->name)
+		__string(name, strlen(lock->name))
 	),
 
 	TP_fast_assign(
@@ -39,7 +39,7 @@ TRACE_EVENT(lock_release,
 	TP_ARGS(lock, nested, ip),
 
 	TP_STRUCT__entry(
-		__string(name, lock->name)
+		__string(name, strlen(lock->name))
 	),
 
 	TP_fast_assign(
@@ -58,7 +58,7 @@ TRACE_EVENT(lock_contended,
 	TP_ARGS(lock, ip),
 
 	TP_STRUCT__entry(
-		__string(name, lock->name)
+		__string(name, strlen(lock->name))
 	),
 
 	TP_fast_assign(
@@ -74,7 +74,7 @@ TRACE_EVENT(lock_acquired,
 	TP_ARGS(lock, ip, waittime),
 
 	TP_STRUCT__entry(
-		__string(name, lock->name)
+		__string(name, strlen(lock->name))
 		__field(unsigned long, wait_usec)
 		__field(unsigned long, wait_nsec_rem)
 	),
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index b5ff2e8..430f7d2 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -25,7 +25,7 @@
 #define __field(type, item)		type	item;
 
 #undef __string
-#define __string(item, src)		unsigned short	__str_loc_##item;
+#define __string(item, len)		unsigned short	__str_loc_##item;
 
 #undef TP_STRUCT__entry
 #define TP_STRUCT__entry(args...) args
@@ -66,7 +66,7 @@
 #define __field(type, item);
 
 #undef __string
-#define __string(item, src)	int item;
+#define __string(item, len)	int item;
 
 #undef TRACE_EVENT
 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)		\
@@ -186,7 +186,7 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags)	\
 		return 0;
 
 #undef __string
-#define __string(item, src)						       \
+#define __string(item, len)						       \
 	ret = trace_seq_printf(s, "\tfield: __str_loc " #item ";\t"	       \
 			       "offset:%u;tsize:%u;\n",			       \
 			       (unsigned int)offsetof(typeof(field),	       \
@@ -239,7 +239,7 @@ ftrace_format_##call(struct trace_seq *s)				\
 		return ret;
 
 #undef __string
-#define __string(item, src)						       \
+#define __string(item, len)						       \
 	ret = trace_define_field(event_call, "__str_loc", #item,	       \
 				offsetof(typeof(field), __str_loc_##item),     \
 				 sizeof(field.__str_loc_##item), 0);
@@ -411,10 +411,15 @@ static void ftrace_profile_disable_##call(struct ftrace_event_call *call) \
 #define __array(type, item, len)
 
 #undef __string
-#define __string(item, src)						       \
-	__str_offsets.item = __str_size +				       \
-			     offsetof(typeof(*entry), __str_data);	       \
-	__str_size += strlen(src) + 1;
+#define __string(item, len)						 \
+	__str_offsets.item = __str_size +				 \
+			     offsetof(typeof(*entry), __str_data);	 \
+	__str_size += (len) + 1;
+
+#undef __fetch_str
+#define __fetch_str(dst)						\
+	({__entry->__str_loc_##dst = __str_offsets.dst;			\
+	__get_str(dst);})
 
 #undef __assign_str
 #define __assign_str(dst, src)						\
-- 
1.5.4.rc3