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// SPDX-License-Identifier: GPL-2.0
/*
* Generic dynamic event control interface
*
* Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org>
*/
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/tracefs.h>
#include "trace.h"
#include "trace_dynevent.h"
static DEFINE_MUTEX(dyn_event_ops_mutex);
static LIST_HEAD(dyn_event_ops_list);
int dyn_event_register(struct dyn_event_operations *ops)
{
if (!ops || !ops->create || !ops->show || !ops->is_busy ||
!ops->free || !ops->match)
return -EINVAL;
INIT_LIST_HEAD(&ops->list);
mutex_lock(&dyn_event_ops_mutex);
list_add_tail(&ops->list, &dyn_event_ops_list);
mutex_unlock(&dyn_event_ops_mutex);
return 0;
}
int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
{
struct dyn_event *pos, *n;
char *system = NULL, *event, *p;
int ret = -ENOENT;
if (argv[0][0] == '-') {
if (argv[0][1] != ':')
return -EINVAL;
event = &argv[0][2];
} else {
event = strchr(argv[0], ':');
if (!event)
return -EINVAL;
event++;
}
p = strchr(event, '/');
if (p) {
system = event;
event = p + 1;
*p = '\0';
}
if (event[0] == '\0')
return -EINVAL;
mutex_lock(&event_mutex);
for_each_dyn_event_safe(pos, n) {
if (type && type != pos->ops)
continue;
if (!pos->ops->match(system, event, pos))
continue;
ret = pos->ops->free(pos);
if (ret)
break;
}
mutex_unlock(&event_mutex);
return ret;
}
static int create_dyn_event(int argc, char **argv)
{
struct dyn_event_operations *ops;
int ret = -ENODEV;
if (argv[0][0] == '-' || argv[0][0] == '!')
return dyn_event_release(argc, argv, NULL);
mutex_lock(&dyn_event_ops_mutex);
list_for_each_entry(ops, &dyn_event_ops_list, list) {
ret = ops->create(argc, (const char **)argv);
if (!ret || ret != -ECANCELED)
break;
}
mutex_unlock(&dyn_event_ops_mutex);
if (ret == -ECANCELED)
ret = -EINVAL;
return ret;
}
/* Protected by event_mutex */
LIST_HEAD(dyn_event_list);
void *dyn_event_seq_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&event_mutex);
return seq_list_start(&dyn_event_list, *pos);
}
void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &dyn_event_list, pos);
}
void dyn_event_seq_stop(struct seq_file *m, void *v)
{
mutex_unlock(&event_mutex);
}
static int dyn_event_seq_show(struct seq_file *m, void *v)
{
struct dyn_event *ev = v;
if (ev && ev->ops)
return ev->ops->show(m, ev);
return 0;
}
static const struct seq_operations dyn_event_seq_op = {
.start = dyn_event_seq_start,
.next = dyn_event_seq_next,
.stop = dyn_event_seq_stop,
.show = dyn_event_seq_show
};
/*
* dyn_events_release_all - Release all specific events
* @type: the dyn_event_operations * which filters releasing events
*
* This releases all events which ->ops matches @type. If @type is NULL,
* all events are released.
* Return -EBUSY if any of them are in use, and return other errors when
* it failed to free the given event. Except for -EBUSY, event releasing
* process will be aborted at that point and there may be some other
* releasable events on the list.
*/
int dyn_events_release_all(struct dyn_event_operations *type)
{
struct dyn_event *ev, *tmp;
int ret = 0;
mutex_lock(&event_mutex);
for_each_dyn_event(ev) {
if (type && ev->ops != type)
continue;
if (ev->ops->is_busy(ev)) {
ret = -EBUSY;
goto out;
}
}
for_each_dyn_event_safe(ev, tmp) {
if (type && ev->ops != type)
continue;
ret = ev->ops->free(ev);
if (ret)
break;
}
out:
mutex_unlock(&event_mutex);
return ret;
}
static int dyn_event_open(struct inode *inode, struct file *file)
{
int ret;
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
ret = dyn_events_release_all(NULL);
if (ret < 0)
return ret;
}
return seq_open(file, &dyn_event_seq_op);
}
static ssize_t dyn_event_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
return trace_parse_run_command(file, buffer, count, ppos,
create_dyn_event);
}
static const struct file_operations dynamic_events_ops = {
.owner = THIS_MODULE,
.open = dyn_event_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
.write = dyn_event_write,
};
/* Make a tracefs interface for controlling dynamic events */
static __init int init_dynamic_event(void)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
if (IS_ERR(d_tracer))
return 0;
entry = tracefs_create_file("dynamic_events", 0644, d_tracer,
NULL, &dynamic_events_ops);
/* Event list interface */
if (!entry)
pr_warn("Could not create tracefs 'dynamic_events' entry\n");
return 0;
}
fs_initcall(init_dynamic_event);
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