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Commit cf027f64 authored by Tom Zanussi's avatar Tom Zanussi Committed by Ingo Molnar
Browse files

tracing: add run-time field descriptions for event filtering 



This patch makes the field descriptions defined for event tracing
available at run-time, for the event-filtering mechanism introduced
in a subsequent patch.

The common event fields are prepended with 'common_' in the format
display, allowing them to be distinguished from the other fields
that might internally have same name and can therefore be
unambiguously used in filters.

Signed-off-by: default avatarTom Zanussi <tzanussi@gmail.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710639.7703.46.camel@charm-linux>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 0cf53ff6

kernel/trace/trace.h

+21 −9
Original line number Diff line number Diff line
@@ -775,6 +775,14 @@ enum { 
	TRACE_EVENT_TYPE_RAW		= 2,

};



struct ftrace_event_field {

	struct list_head	link;

	char			*name;

	char			*type;

	int			offset;

	int			size;

};



struct ftrace_event_call {

	char			*name;

	char			*system;
@@ -785,6 +793,8 @@ struct ftrace_event_call { 
	int			id;

	int			(*raw_init)(void);

	int			(*show_format)(struct trace_seq *s);

	int			(*define_fields)(void);

	struct list_head	fields;



#ifdef CONFIG_EVENT_PROFILE

	atomic_t	profile_count;
@@ -793,6 +803,8 @@ struct ftrace_event_call { 
#endif

};



int trace_define_field(struct ftrace_event_call *call, char *type,

		       char *name, int offset, int size);

void event_trace_printk(unsigned long ip, const char *fmt, ...);

extern struct ftrace_event_call __start_ftrace_events[];

extern struct ftrace_event_call __stop_ftrace_events[];

kernel/trace/trace_events.c

+39 −1
Original line number Diff line number Diff line
@@ -19,6 +19,34 @@ 


static DEFINE_MUTEX(event_mutex);



int trace_define_field(struct ftrace_event_call *call, char *type,

		       char *name, int offset, int size)

{

	struct ftrace_event_field *field;



	field = kmalloc(sizeof(*field), GFP_KERNEL);

	if (!field)

		goto err;

	field->name = kstrdup(name, GFP_KERNEL);

	if (!field->name)

		goto err;

	field->type = kstrdup(type, GFP_KERNEL);

	if (!field->type)

		goto err;

	field->offset = offset;

	field->size = size;

	list_add(&field->link, &call->fields);



	return 0;

err:

	if (field) {

		kfree(field->name);

		kfree(field->type);

	}

	kfree(field);

	return -ENOMEM;

}



static void ftrace_clear_events(void)

{

	struct ftrace_event_call *call = (void *)__start_ftrace_events;
@@ -343,7 +371,8 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, 


#undef FIELD

#define FIELD(type, name)						\

	#type, #name, offsetof(typeof(field), name), sizeof(field.name)

	#type, "common_" #name, offsetof(typeof(field), name),		\

		sizeof(field.name)



static int trace_write_header(struct trace_seq *s)

{
@@ -581,6 +610,15 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events) 
					call->name);

	}



	if (call->define_fields) {

		ret = call->define_fields();

		if (ret < 0) {

			pr_warning("Could not initialize trace point"

				   " events/%s\n", call->name);

			return ret;

		}

	}



	/* A trace may not want to export its format */

	if (!call->show_format)

		return 0;

kernel/trace/trace_events_stage_2.h

+45 −0
Original line number Diff line number Diff line
@@ -129,3 +129,48 @@ ftrace_format_##call(struct trace_seq *s) \ 
}



#include <trace/trace_event_types.h>



#undef __field

#define __field(type, item)						\

	ret = trace_define_field(event_call, #type, #item,		\

				 offsetof(typeof(field), item),		\

				 sizeof(field.item));			\

	if (ret)							\

		return ret;



#undef __array

#define __array(type, item, len)					\

	ret = trace_define_field(event_call, #type "[" #len "]", #item,	\

				 offsetof(typeof(field), item),		\

				 sizeof(field.item));			\

	if (ret)							\

		return ret;



#define __common_field(type, item)					\

	ret = trace_define_field(event_call, #type, "common_" #item,	\

				 offsetof(typeof(field.ent), item),	\

				 sizeof(field.ent.item));		\

	if (ret)							\

		return ret;



#undef TRACE_EVENT

#define TRACE_EVENT(call, proto, args, tstruct, func, print)		\

int									\

ftrace_define_fields_##call(void)					\

{									\

	struct ftrace_raw_##call field;					\

	struct ftrace_event_call *event_call = &event_##call;		\

	int ret;							\

									\

	__common_field(unsigned char, type);				\

	__common_field(unsigned char, flags);				\

	__common_field(unsigned char, preempt_count);			\

	__common_field(int, pid);					\

	__common_field(int, tgid);					\

									\

	tstruct;							\

									\

	return ret;							\

}



#include <trace/trace_event_types.h>

kernel/trace/trace_events_stage_3.h

+2 −0
Original line number Diff line number Diff line
@@ -252,6 +252,7 @@ static int ftrace_raw_init_event_##call(void) \ 
	if (!id)							\

		return -ENODEV;						\

	event_##call.id = id;						\

	INIT_LIST_HEAD(&event_##call.fields);				\

	return 0;							\

}									\

									\
@@ -264,6 +265,7 @@ __attribute__((section("_ftrace_events"))) event_##call = { \ 
	.regfunc		= ftrace_raw_reg_event_##call,		\

	.unregfunc		= ftrace_raw_unreg_event_##call,	\

	.show_format		= ftrace_format_##call,			\

	.define_fields		= ftrace_define_fields_##call,		\

	_TRACE_PROFILE_INIT(call)					\

}