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Commit 23725aee authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

ftrace: provide an id file for each event 



Since not every event has a format file to read the id from,
expose it explicitly in a separate file.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.372534033@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 44fc6ee9

kernel/trace/trace_events.c

+36 −0
Original line number Diff line number Diff line
@@ -412,6 +412,29 @@ event_format_read(struct file *filp, char __user *ubuf, size_t cnt, 
	return r;

}



static ssize_t

event_id_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;

	int r;



	if (*ppos)

		return 0;



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

	if (!s)

		return -ENOMEM;



	trace_seq_init(s);

	trace_seq_printf(s, "%d\n", call->id);



	r = simple_read_from_buffer(ubuf, cnt, ppos,

				    s->buffer, s->len);

	kfree(s);

	return r;

}



static const struct seq_operations show_event_seq_ops = {

	.start = t_start,

	.next = t_next,
@@ -452,6 +475,11 @@ static const struct file_operations ftrace_event_format_fops = { 
	.read = event_format_read,

};



static const struct file_operations ftrace_event_id_fops = {

	.open = tracing_open_generic,

	.read = event_id_read,

};



static struct dentry *event_trace_events_dir(void)

{

	static struct dentry *d_tracer;
@@ -550,6 +578,14 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events) 
				   "'%s/enable' entry\n", call->name);

	}



	if (call->id) {

		entry = debugfs_create_file("id", 0444, call->dir, call,

				&ftrace_event_id_fops);

		if (!entry)

			pr_warning("Could not create debugfs '%s/id' entry\n",

					call->name);

	}



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

	if (!call->show_format)

		return 0;