[PATCH 0/7] [GIT PULL] trace event updates for tip

[PATCH 0/7] [GIT PULL] trace event updates for tip

[Steven Rostedt]

Ingo,

Please pull the latest tip/tracing/ftrace tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/tracing/ftrace


Steven Rostedt (7):
      tracing: add TRACE_FIELD_SPECIAL to record complex entries
      tracing: add protection around modify trace event fields
      tracing: make trace_seq_reset global and rename to trace_seq_init
      tracing: add format file to describe event struct fields
      tracing: add ftrace headers to event format files
      tracing: add trace name and id to event formats
      tracing: add print format to event trace format files

----
 include/trace/sched_event_types.h   |    7 ++-
 kernel/trace/trace.c                |   17 ++-----
 kernel/trace/trace.h                |    9 +++
 kernel/trace/trace_events.c         |   94 ++++++++++++++++++++++++++++++++++-
 kernel/trace/trace_events_stage_1.h |    2 +
 kernel/trace/trace_events_stage_2.h |   58 +++++++++++++++++++++
 kernel/trace/trace_events_stage_3.h |   16 ++++++
 7 files changed, 188 insertions(+), 15 deletions(-)
-- 

[PATCH 1/7] tracing: add TRACE_FIELD_SPECIAL to record complex entries

[Steven Rostedt]

[-- Attachment #1: 0001-tracing-add-TRACE_FIELD_SPECIAL-to-record-complex-e.patch --]
[-- Type: text/plain, Size: 4527 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Tom Zanussi pointed out that the simple TRACE_FIELD was not enough to
record trace data that required memcpy. This patch addresses this issue
by adding a TRACE_FIELD_SPECIAL. The format is similar to TRACE_FIELD
but looks like so:

  TRACE_FIELD_SPECIAL(type_item, item, cmd)

What TRACE_FIELD gave was:

  TRACE_FIELD(type, item, assign)

The TRACE_FIELD would be used in declaring a structure:

  struct {
	type	item;
  };

And later assign it via:

  entry->item = assign;

What TRACE_FIELD_SPECIAL gives us is:

In the declaration of the structure:

  struct {
	type_item;
  };

And the assignment:

  cmd;

This change log will explain the one example used in the patch:

 TRACE_EVENT_FORMAT(sched_switch,
	TPPROTO(struct rq *rq, struct task_struct *prev,
		struct task_struct *next),
	TPARGS(rq, prev, next),
	TPFMT("task %s:%d ==> %s:%d",
	      prev->comm, prev->pid, next->comm, next->pid),
	TRACE_STRUCT(
		TRACE_FIELD(pid_t, prev_pid, prev->pid)
		TRACE_FIELD(int, prev_prio, prev->prio)
		TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
				    next_comm,
				    TPCMD(memcpy(TRACE_ENTRY->next_comm,
						 next->comm,
						 TASK_COMM_LEN)))
		TRACE_FIELD(pid_t, next_pid, next->pid)
		TRACE_FIELD(int, next_prio, next->prio)
	),
	TPRAWFMT("prev %d:%d ==> next %s:%d:%d")
	);

 The struct will be create as:

  struct {
	pid_t		prev_pid;
	int		prev_prio;
	char next_comm[TASK_COMM_LEN];
	pid_t		next_pid;
	int		next_prio;
  };

Note the TRACE_ENTRY in the cmd part of TRACE_SPECIAL. TRACE_ENTRY will
be set by the tracer to point to the structure inside the trace buffer.

  entry->prev_pid	= prev->pid;
  entry->prev_prio	= prev->prio;
  memcpy(entry->next_comm, next->comm, TASK_COMM_LEN);
  entry->next_pid	= next->pid;
  entry->next_prio	= next->prio

Reported-by: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 include/trace/sched_event_types.h   |    7 ++++++-
 kernel/trace/trace_events_stage_1.h |    2 ++
 kernel/trace/trace_events_stage_2.h |    4 ++++
 kernel/trace/trace_events_stage_3.h |   14 ++++++++++++++
 4 files changed, 26 insertions(+), 1 deletions(-)

diff --git a/include/trace/sched_event_types.h b/include/trace/sched_event_types.h
index ba059c1..a6de5c1 100644
--- a/include/trace/sched_event_types.h
+++ b/include/trace/sched_event_types.h
@@ -71,10 +71,15 @@ TRACE_EVENT_FORMAT(sched_switch,
 	TRACE_STRUCT(
 		TRACE_FIELD(pid_t, prev_pid, prev->pid)
 		TRACE_FIELD(int, prev_prio, prev->prio)
+		TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
+				    next_comm,
+				    TPCMD(memcpy(TRACE_ENTRY->next_comm,
+						 next->comm,
+						 TASK_COMM_LEN)))
 		TRACE_FIELD(pid_t, next_pid, next->pid)
 		TRACE_FIELD(int, next_prio, next->prio)
 	),
-	TPRAWFMT("prev %d:%d ==> next %d:%d")
+	TPRAWFMT("prev %d:%d ==> next %s:%d:%d")
 	);
 
 TRACE_EVENT_FORMAT(sched_migrate_task,
diff --git a/kernel/trace/trace_events_stage_1.h b/kernel/trace/trace_events_stage_1.h
index fd3bf93..3830a73 100644
--- a/kernel/trace/trace_events_stage_1.h
+++ b/kernel/trace/trace_events_stage_1.h
@@ -30,5 +30,7 @@
 
 #define TRACE_FIELD(type, item, assign) \
 	type item;
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+	type_item;
 
 #include <trace/trace_event_types.h>
diff --git a/kernel/trace/trace_events_stage_2.h b/kernel/trace/trace_events_stage_2.h
index 3eaaef5..dc79fe3 100644
--- a/kernel/trace/trace_events_stage_2.h
+++ b/kernel/trace/trace_events_stage_2.h
@@ -39,6 +39,10 @@
 #define TRACE_FIELD(type, item, assign) \
 	field->item,
 
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+	field->item,
+
 
 #undef TPRAWFMT
 #define TPRAWFMT(args...)	args
diff --git a/kernel/trace/trace_events_stage_3.h b/kernel/trace/trace_events_stage_3.h
index 7a161c4..2ab65e9 100644
--- a/kernel/trace/trace_events_stage_3.h
+++ b/kernel/trace/trace_events_stage_3.h
@@ -147,6 +147,20 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
 #define TRACE_FIELD(type, item, assign)\
 	entry->item = assign;
 
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)\
+	entry->item = assign;
+
+#undef TPCMD
+#define TPCMD(cmd...)	cmd
+
+#undef TRACE_ENTRY
+#define TRACE_ENTRY	entry
+
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+	cmd;
+
 #undef TRACE_EVENT_FORMAT
 #define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)	\
 _TRACE_FORMAT(call, PARAMS(proto), PARAMS(args), PARAMS(fmt))		\
-- 
1.5.6.5

-- 

[PATCH 2/7] tracing: add protection around modify trace event fields

[Steven Rostedt]

[-- Attachment #1: 0002-tracing-add-protection-around-modify-trace-event-fi.patch --]
[-- Type: text/plain, Size: 1349 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The trace event objects are currently not proctected against
reentrancy. This patch adds a mutex around the modifications of
the trace event fields.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace_events.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 1d07f80..26069fa 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -14,6 +14,8 @@
 
 #define TRACE_SYSTEM "TRACE_SYSTEM"
 
+static DEFINE_MUTEX(event_mutex);
+
 #define events_for_each(event)						\
 	for (event = __start_ftrace_events;				\
 	     (unsigned long)event < (unsigned long)__stop_ftrace_events; \
@@ -104,6 +106,7 @@ static int ftrace_set_clr_event(char *buf, int set)
 			event = NULL;
 	}
 
+	mutex_lock(&event_mutex);
 	events_for_each(call) {
 
 		if (!call->name)
@@ -124,6 +127,8 @@ static int ftrace_set_clr_event(char *buf, int set)
 
 		ret = 0;
 	}
+	mutex_unlock(&event_mutex);
+
 	return ret;
 }
 
@@ -324,7 +329,9 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 	switch (val) {
 	case 0:
 	case 1:
+		mutex_lock(&event_mutex);
 		ftrace_event_enable_disable(call, val);
+		mutex_unlock(&event_mutex);
 		break;
 
 	default:
-- 
1.5.6.5

-- 

[PATCH 3/7] tracing: make trace_seq_reset global and rename to trace_seq_init

[Steven Rostedt]

[-- Attachment #1: 0003-tracing-make-trace_seq_reset-global-and-rename-to-t.patch --]
[-- Type: text/plain, Size: 2473 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Impact: clean up

The trace_seq functions may be used separately outside of the ftrace
iterator. The trace_seq_reset is needed for these operations.

This patch also renames trace_seq_reset to the more appropriate
trace_seq_init.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace.c |   17 +++++------------
 kernel/trace/trace.h |    8 ++++++++
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c5e39cd..ea055aa 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -342,13 +342,6 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 	tracing_record_cmdline(tsk);
 }
 
-static void
-trace_seq_reset(struct trace_seq *s)
-{
-	s->len = 0;
-	s->readpos = 0;
-}
-
 ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
 {
 	int len;
@@ -395,7 +388,7 @@ trace_print_seq(struct seq_file *m, struct trace_seq *s)
 	s->buffer[len] = 0;
 	seq_puts(m, s->buffer);
 
-	trace_seq_reset(s);
+	trace_seq_init(s);
 }
 
 /**
@@ -2620,7 +2613,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 	if (sret != -EBUSY)
 		return sret;
 
-	trace_seq_reset(&iter->seq);
+	trace_seq_init(&iter->seq);
 
 	/* copy the tracer to avoid using a global lock all around */
 	mutex_lock(&trace_types_lock);
@@ -2682,7 +2675,7 @@ waitagain:
 	/* Now copy what we have to the user */
 	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
 	if (iter->seq.readpos >= iter->seq.len)
-		trace_seq_reset(&iter->seq);
+		trace_seq_init(&iter->seq);
 
 	/*
 	 * If there was nothing to send to user, inspite of consuming trace
@@ -2819,7 +2812,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		partial[i].offset = 0;
 		partial[i].len = iter->seq.len;
 
-		trace_seq_reset(&iter->seq);
+		trace_seq_init(&iter->seq);
 	}
 
 	mutex_unlock(&iter->mutex);
@@ -3631,7 +3624,7 @@ trace_printk_seq(struct trace_seq *s)
 
 	printk(KERN_TRACE "%s", s->buffer);
 
-	trace_seq_reset(s);
+	trace_seq_init(s);
 }
 
 void ftrace_dump(void)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f6fa0b9..cf6ba41 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -395,6 +395,14 @@ struct trace_seq {
 	unsigned int		readpos;
 };
 
+static inline void
+trace_seq_init(struct trace_seq *s)
+{
+	s->len = 0;
+	s->readpos = 0;
+}
+
+
 #define TRACE_PIPE_ALL_CPU	-1
 
 /*
-- 
1.5.6.5

-- 

[PATCH 4/7] tracing: add format file to describe event struct fields

[Steven Rostedt]

[-- Attachment #1: 0004-tracing-add-format-file-to-describe-event-struct-fi.patch --]
[-- Type: text/plain, Size: 6121 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

This patch adds the "format" file to the trace point event directory.
This is based off of work by Tom Zanussi, in which a file is exported
to be tread from user land such that a user space app may read the
binary record stored in the ring buffer.

 # cat /debug/tracing/events/sched/sched_switch/format
        field:pid_t prev_pid;   offset:12;      size:4;
        field:int prev_prio;    offset:16;      size:4;
        field special:char next_comm[TASK_COMM_LEN];    offset:20;      size:16;
        field:pid_t next_pid;   offset:36;      size:4;
        field:int next_prio;    offset:40;      size:4;

Idea-from: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace.h                |    1 +
 kernel/trace/trace_events.c         |   56 ++++++++++++++++++++++++++++++++++-
 kernel/trace/trace_events_stage_2.h |   52 ++++++++++++++++++++++++++++++++
 kernel/trace/trace_events_stage_3.h |    2 +
 4 files changed, 110 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index cf6ba41..e606633 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -754,6 +754,7 @@ struct ftrace_event_call {
 	int		(*raw_init)(void);
 	int		(*raw_reg)(void);
 	void		(*raw_unreg)(void);
+	int		(*show_format)(struct trace_seq *s);
 };
 
 void event_trace_printk(unsigned long ip, const char *fmt, ...);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 26069fa..d57a772 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3,6 +3,9 @@
  *
  * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
  *
+ *  - Added format output of fields of the trace point.
+ *    This was based off of work by Tom Zanussi <tzanussi@gmail.com>.
+ *
  */
 
 #include <linux/debugfs.h>
@@ -444,6 +447,42 @@ event_available_types_read(struct file *filp, char __user *ubuf, size_t cnt,
 	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
 
+static ssize_t
+event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
+		  loff_t *ppos)
+{
+	struct ftrace_event_call *call = filp->private_data;
+	struct trace_seq *s;
+	char *buf;
+	int r;
+
+	s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	trace_seq_init(s);
+
+	if (*ppos)
+		return 0;
+
+	r = call->show_format(s);
+	if (!r) {
+		/*
+		 * ug!  The format output is bigger than a PAGE!!
+		 */
+		buf = "FORMAT TOO BIG\n";
+		r = simple_read_from_buffer(ubuf, cnt, ppos,
+					      buf, strlen(buf));
+		goto out;
+	}
+
+	r = simple_read_from_buffer(ubuf, cnt, ppos,
+				    s->buffer, s->len);
+ out:
+	kfree(s);
+	return r;
+}
+
 static const struct seq_operations show_event_seq_ops = {
 	.start = t_start,
 	.next = t_next,
@@ -490,6 +529,11 @@ static const struct file_operations ftrace_available_types_fops = {
 	.read = event_available_types_read,
 };
 
+static const struct file_operations ftrace_event_format_fops = {
+	.open = tracing_open_generic,
+	.read = event_format_read,
+};
+
 static struct dentry *event_trace_events_dir(void)
 {
 	static struct dentry *d_tracer;
@@ -602,7 +646,17 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 				    &ftrace_available_types_fops);
 	if (!entry)
 		pr_warning("Could not create debugfs "
-			   "'%s/type' available_types\n", call->name);
+			   "'%s/available_types' entry\n", call->name);
+
+	/* A trace may not want to export its format */
+	if (!call->show_format)
+		return 0;
+
+	entry = debugfs_create_file("format", 0444, call->dir, call,
+				    &ftrace_event_format_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'%s/format' entry\n", call->name);
 
 	return 0;
 }
diff --git a/kernel/trace/trace_events_stage_2.h b/kernel/trace/trace_events_stage_2.h
index dc79fe3..3a80ea4 100644
--- a/kernel/trace/trace_events_stage_2.h
+++ b/kernel/trace/trace_events_stage_2.h
@@ -74,3 +74,55 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags)	\
 }
 
 #include <trace/trace_event_types.h>
+
+/*
+ * Setup the showing format of trace point.
+ *
+ * int
+ * ftrace_format_##call(struct trace_seq *s)
+ * {
+ * 	struct ftrace_raw_##call field;
+ * 	int ret;
+ *
+ * 	ret = trace_seq_printf(s, #type " " #item ";"
+ * 			       " size:%d; offset:%d;\n",
+ * 			       sizeof(field.type),
+ * 			       offsetof(struct ftrace_raw_##call,
+ * 					item));
+ *
+ * }
+ */
+
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)					\
+	ret = trace_seq_printf(s, "\tfield:" #type " " #item ";\t"	\
+			       "offset:%lu;\tsize:%lu;\n",		\
+			       offsetof(typeof(field), item),		\
+			       sizeof(field.item));			\
+	if (!ret)							\
+		return 0;
+
+
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd)			\
+	ret = trace_seq_printf(s, "\tfield special:" #type_item ";\t"	\
+			       "offset:%lu;\tsize:%lu;\n",		\
+			       offsetof(typeof(field), item),		\
+			       sizeof(field.item));			\
+	if (!ret)							\
+		return 0;
+
+#undef TRACE_EVENT_FORMAT
+#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)	\
+int									\
+ftrace_format_##call(struct trace_seq *s)				\
+{									\
+	struct ftrace_raw_##call field;					\
+	int ret;							\
+									\
+	tstruct;							\
+									\
+	return ret;							\
+}
+
+#include <trace/trace_event_types.h>
diff --git a/kernel/trace/trace_events_stage_3.h b/kernel/trace/trace_events_stage_3.h
index 2ab65e9..c62a4d2 100644
--- a/kernel/trace/trace_events_stage_3.h
+++ b/kernel/trace/trace_events_stage_3.h
@@ -101,6 +101,7 @@
  * 	.raw_init		= ftrace_raw_init_event_<call>,
  * 	.raw_reg		= ftrace_raw_reg_event_<call>,
  * 	.raw_unreg		= ftrace_raw_unreg_event_<call>,
+ *	.show_format		= ftrace_format_<call>,
  * }
  *
  */
@@ -230,4 +231,5 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
 	.raw_init		= ftrace_raw_init_event_##call,		\
 	.raw_reg		= ftrace_raw_reg_event_##call,		\
 	.raw_unreg		= ftrace_raw_unreg_event_##call,	\
+	.show_format		= ftrace_format_##call,			\
 }
-- 
1.5.6.5

-- 

Re: [PATCH 4/7] tracing: add format file to describe event struct fields

[Andrew Morton]

On Mon, 02 Mar 2009 15:29:29 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: Steven Rostedt <srostedt@redhat.com>
> 
> This patch adds the "format" file to the trace point event directory.
> This is based off of work by Tom Zanussi, in which a file is exported
> to be tread from user land such that a user space app may read the

s/tread/read/

> binary record stored in the ring buffer.
>
> ...
>
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -3,6 +3,9 @@
>   *
>   * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
>   *
> + *  - Added format output of fields of the trace point.
> + *    This was based off of work by Tom Zanussi <tzanussi@gmail.com>.

ick.  "based on"

> + *
>   */
>  
>  #include <linux/debugfs.h>
> @@ -444,6 +447,42 @@ event_available_types_read(struct file *filp, char __user *ubuf, size_t cnt,
>  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
>  }
>  
> +static ssize_t
> +event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
> +		  loff_t *ppos)
> +{
> +	struct ftrace_event_call *call = filp->private_data;
> +	struct trace_seq *s;
> +	char *buf;
> +	int r;
> +
> +	s = kmalloc(sizeof(*s), GFP_KERNEL);
> +	if (!s)
> +		return -ENOMEM;
> +
> +	trace_seq_init(s);
> +
> +	if (*ppos)
> +		return 0;

Someone get this man a bucket!

> +	r = call->show_format(s);
> +	if (!r) {
> +		/*
> +		 * ug!  The format output is bigger than a PAGE!!
> +		 */
> +		buf = "FORMAT TOO BIG\n";
> +		r = simple_read_from_buffer(ubuf, cnt, ppos,
> +					      buf, strlen(buf));
> +		goto out;
> +	}
> +
> +	r = simple_read_from_buffer(ubuf, cnt, ppos,
> +				    s->buffer, s->len);
> + out:
> +	kfree(s);
> +	return r;
> +}

[PATCH 5/7] tracing: add ftrace headers to event format files

[Steven Rostedt]

[-- Attachment #1: 0005-tracing-add-ftrace-headers-to-event-format-files.patch --]
[-- Type: text/plain, Size: 2545 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

This patch includes the ftrace header to the event formats files:

 # cat /debug/tracing/events/sched/sched_switch/format
        field:unsigned char type;       offset:0;       size:1;
        field:unsigned char flags;      offset:1;       size:1;
        field:unsigned char preempt_count;      offset:2;       size:1;
        field:int pid;  offset:4;       size:4;
        field:int tgid; offset:8;       size:4;

        field:pid_t prev_pid;   offset:12;      size:4;
        field:int prev_prio;    offset:16;      size:4;
        field special:char next_comm[TASK_COMM_LEN];    offset:20;      size:16;
        field:pid_t next_pid;   offset:36;      size:4;
        field:int next_prio;    offset:40;      size:4;

A blank line is used as a deliminator between the ftrace header and the
trace point fields.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace_events.c |   27 ++++++++++++++++++++++++++-
 1 files changed, 26 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index d57a772..cdcc3ae 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -13,7 +13,7 @@
 #include <linux/module.h>
 #include <linux/ctype.h>
 
-#include "trace.h"
+#include "trace_output.h"
 
 #define TRACE_SYSTEM "TRACE_SYSTEM"
 
@@ -447,6 +447,28 @@ event_available_types_read(struct file *filp, char __user *ubuf, size_t cnt,
 	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
 
+#undef FIELD
+#define FIELD(type, name) \
+	#type, #name, offsetof(typeof(field), name), sizeof(field.name)
+
+static int trace_write_header(struct trace_seq *s)
+{
+	struct trace_entry field;
+
+	/* struct trace_entry */
+	return trace_seq_printf(s,
+				"\tfield:%s %s;\toffset:%lu;\tsize:%lu;\n"
+				"\tfield:%s %s;\toffset:%lu;\tsize:%lu;\n"
+				"\tfield:%s %s;\toffset:%lu;\tsize:%lu;\n"
+				"\tfield:%s %s;\toffset:%lu;\tsize:%lu;\n"
+				"\tfield:%s %s;\toffset:%lu;\tsize:%lu;\n"
+				"\n",
+				FIELD(unsigned char, type),
+				FIELD(unsigned char, flags),
+				FIELD(unsigned char, preempt_count),
+				FIELD(int, pid),
+				FIELD(int, tgid));
+}
 static ssize_t
 event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
 		  loff_t *ppos)
@@ -465,6 +487,9 @@ event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
 	if (*ppos)
 		return 0;
 
+	/* If this fails, so will the show_format. */
+	trace_write_header(s);
+
 	r = call->show_format(s);
 	if (!r) {
 		/*
-- 
1.5.6.5

-- 

[PATCH 6/7] tracing: add trace name and id to event formats

[Steven Rostedt]

[-- Attachment #1: 0006-tracing-add-trace-name-and-id-to-event-formats.patch --]
[-- Type: text/plain, Size: 1013 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

To be able to identify the trace in the binary format output, the
id of the trace event (which is dynamically assigned) must also be listed.

This patch adds the name of the trace point as well as the id assigned.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace_events.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index cdcc3ae..210e71f 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -487,7 +487,11 @@ event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
 	if (*ppos)
 		return 0;
 
-	/* If this fails, so will the show_format. */
+	/* If any of the first writes fail, so will the show_format. */
+
+	trace_seq_printf(s, "name: %s\n", call->name);
+	trace_seq_printf(s, "ID: %d\n", call->id);
+	trace_seq_printf(s, "format:\n");
 	trace_write_header(s);
 
 	r = call->show_format(s);
-- 
1.5.6.5

-- 

[PATCH 7/7] tracing: add print format to event trace format files

[Steven Rostedt]

[-- Attachment #1: 0007-tracing-add-print-format-to-event-trace-format-file.patch --]
[-- Type: text/plain, Size: 1468 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

This patch adds the internal print format used to print the raw events
to the event trace point format file.

 # cat /debug/tracing/events/sched/sched_switch/format
name: sched_switch
ID: 29
format:
        field:unsigned char type;       offset:0;       size:1;
        field:unsigned char flags;      offset:1;       size:1;
        field:unsigned char preempt_count;      offset:2;       size:1;
        field:int pid;  offset:4;       size:4;
        field:int tgid; offset:8;       size:4;

        field:pid_t prev_pid;   offset:12;      size:4;
        field:int prev_prio;    offset:16;      size:4;
        field special:char next_comm[TASK_COMM_LEN];    offset:20;      size:16;
        field:pid_t next_pid;   offset:36;      size:4;
        field:int next_prio;    offset:40;      size:4;

print fmt: "prev %d:%d ==> next %s:%d:%d"

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace_events_stage_2.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_events_stage_2.h b/kernel/trace/trace_events_stage_2.h
index 3a80ea4..b1cebba 100644
--- a/kernel/trace/trace_events_stage_2.h
+++ b/kernel/trace/trace_events_stage_2.h
@@ -122,6 +122,8 @@ ftrace_format_##call(struct trace_seq *s)				\
 									\
 	tstruct;							\
 									\
+	trace_seq_printf(s, "\nprint fmt: \"%s\"\n", tpfmt);		\
+									\
 	return ret;							\
 }
 
-- 
1.5.6.5

--