tracing: make event directory structure
This patch adds the directory /debug/tracing/events/ that will contain
all the registered trace points.
# ls /debug/tracing/events/
sched_kthread_stop sched_process_fork sched_switch
sched_kthread_stop_ret sched_process_free sched_wait_task
sched_migrate_task sched_process_wait sched_wakeup
sched_process_exit sched_signal_send sched_wakeup_new
# ls /debug/tracing/events/sched_switch/
enable
# cat /debug/tracing/events/sched_switch/enable
1
# cat /debug/tracing/set_event
sched_switch
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 05bc80e..3bcb9df 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -12,6 +12,11 @@
#include "trace_events.h"
+#define events_for_each(event) \
+ for (event = __start_ftrace_events; \
+ (unsigned long)event < (unsigned long)__stop_ftrace_events; \
+ event++)
+
void event_trace_printk(unsigned long ip, const char *fmt, ...)
{
va_list ap;
@@ -39,15 +44,16 @@
static int ftrace_set_clr_event(char *buf, int set)
{
- struct ftrace_event_call *call = (void *)__start_ftrace_events;
+ struct ftrace_event_call *call = __start_ftrace_events;
- while ((unsigned long)call < (unsigned long)__stop_ftrace_events) {
+ events_for_each(call) {
- if (strcmp(buf, call->name) != 0) {
- call++;
+ if (!call->name)
continue;
- }
+
+ if (strcmp(buf, call->name) != 0)
+ continue;
if (set) {
/* Already set? */
@@ -223,6 +229,67 @@
return ret;
}
+static ssize_t
+event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
+ loff_t *ppos)
+{
+ struct ftrace_event_call *call = filp->private_data;
+ char *buf;
+
+ if (call->enabled)
+ buf = "1\n";
+ else
+ buf = "0\n";
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
+}
+
+static ssize_t
+event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
+ loff_t *ppos)
+{
+ struct ftrace_event_call *call = filp->private_data;
+ char buf[64];
+ unsigned long val;
+ int ret;
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ ret = strict_strtoul(buf, 10, &val);
+ if (ret < 0)
+ return ret;
+
+ switch (val) {
+ case 0:
+ if (!call->enabled)
+ break;
+
+ call->enabled = 0;
+ call->unregfunc();
+ break;
+ case 1:
+ if (call->enabled)
+ break;
+
+ call->enabled = 1;
+ call->regfunc();
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ *ppos += cnt;
+
+ return cnt;
+}
+
static const struct seq_operations show_event_seq_ops = {
.start = t_start,
.next = t_next,
@@ -252,10 +319,59 @@
.release = seq_release,
};
+static const struct file_operations ftrace_enable_fops = {
+ .open = tracing_open_generic,
+ .read = event_enable_read,
+ .write = event_enable_write,
+};
+
+static struct dentry *event_trace_events_dir(void)
+{
+ static struct dentry *d_tracer;
+ static struct dentry *d_events;
+
+ if (d_events)
+ return d_events;
+
+ d_tracer = tracing_init_dentry();
+ if (!d_tracer)
+ return NULL;
+
+ d_events = debugfs_create_dir("events", d_tracer);
+ if (!d_events)
+ pr_warning("Could not create debugfs "
+ "'events' directory\n");
+
+ return d_events;
+}
+
+static int
+event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
+{
+ struct dentry *entry;
+
+ call->dir = debugfs_create_dir(call->name, d_events);
+ if (!call->dir) {
+ pr_warning("Could not create debugfs "
+ "'%s' directory\n", call->name);
+ return -1;
+ }
+
+ entry = debugfs_create_file("enable", 0644, call->dir, call,
+ &ftrace_enable_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs "
+ "'%s/enable' entry\n", call->name);
+
+ return 0;
+}
+
static __init int event_trace_init(void)
{
+ struct ftrace_event_call *call = __start_ftrace_events;
struct dentry *d_tracer;
struct dentry *entry;
+ struct dentry *d_events;
d_tracer = tracing_init_dentry();
if (!d_tracer)
@@ -275,6 +391,17 @@
pr_warning("Could not create debugfs "
"'set_event' entry\n");
+ d_events = event_trace_events_dir();
+ if (!d_events)
+ return 0;
+
+ events_for_each(call) {
+ /* The linker may leave blanks */
+ if (!call->name)
+ continue;
+ event_create_dir(call, d_events);
+ }
+
return 0;
}
fs_initcall(event_trace_init);
