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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: Peter 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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-03-19 20:26:13 +01:00 committed by Ingo Molnar
parent 44fc6ee923
commit 23725aeeab
1 changed files with 36 additions and 0 deletions
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36
kernel/trace/trace_events.c
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@ -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;