1 // SPDX-License-Identifier: GPL-2.0
3 * Generic dynamic event control interface
5 * Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org>
8 #include <linux/debugfs.h>
9 #include <linux/kernel.h>
10 #include <linux/list.h>
12 #include <linux/mutex.h>
13 #include <linux/tracefs.h>
16 #include "trace_dynevent.h"
18 static DEFINE_MUTEX(dyn_event_ops_mutex);
19 static LIST_HEAD(dyn_event_ops_list);
21 int dyn_event_register(struct dyn_event_operations *ops)
23 if (!ops || !ops->create || !ops->show || !ops->is_busy ||
24 !ops->free || !ops->match)
27 INIT_LIST_HEAD(&ops->list);
28 mutex_lock(&dyn_event_ops_mutex);
29 list_add_tail(&ops->list, &dyn_event_ops_list);
30 mutex_unlock(&dyn_event_ops_mutex);
34 int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
36 struct dyn_event *pos, *n;
37 char *system = NULL, *event, *p;
40 if (argv[0][0] == '-') {
41 if (argv[0][1] != ':')
45 event = strchr(argv[0], ':');
52 p = strchr(event, '/');
61 mutex_lock(&event_mutex);
62 for_each_dyn_event_safe(pos, n) {
63 if (type && type != pos->ops)
65 if (!pos->ops->match(system, event,
66 argc, (const char **)argv, pos))
69 ret = pos->ops->free(pos);
73 tracing_reset_all_online_cpus();
74 mutex_unlock(&event_mutex);
79 static int create_dyn_event(int argc, char **argv)
81 struct dyn_event_operations *ops;
84 if (argv[0][0] == '-' || argv[0][0] == '!')
85 return dyn_event_release(argc, argv, NULL);
87 mutex_lock(&dyn_event_ops_mutex);
88 list_for_each_entry(ops, &dyn_event_ops_list, list) {
89 ret = ops->create(argc, (const char **)argv);
90 if (!ret || ret != -ECANCELED)
93 mutex_unlock(&dyn_event_ops_mutex);
94 if (ret == -ECANCELED)
100 /* Protected by event_mutex */
101 LIST_HEAD(dyn_event_list);
103 void *dyn_event_seq_start(struct seq_file *m, loff_t *pos)
105 mutex_lock(&event_mutex);
106 return seq_list_start(&dyn_event_list, *pos);
109 void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
111 return seq_list_next(v, &dyn_event_list, pos);
114 void dyn_event_seq_stop(struct seq_file *m, void *v)
116 mutex_unlock(&event_mutex);
119 static int dyn_event_seq_show(struct seq_file *m, void *v)
121 struct dyn_event *ev = v;
124 return ev->ops->show(m, ev);
129 static const struct seq_operations dyn_event_seq_op = {
130 .start = dyn_event_seq_start,
131 .next = dyn_event_seq_next,
132 .stop = dyn_event_seq_stop,
133 .show = dyn_event_seq_show
137 * dyn_events_release_all - Release all specific events
138 * @type: the dyn_event_operations * which filters releasing events
140 * This releases all events which ->ops matches @type. If @type is NULL,
141 * all events are released.
142 * Return -EBUSY if any of them are in use, and return other errors when
143 * it failed to free the given event. Except for -EBUSY, event releasing
144 * process will be aborted at that point and there may be some other
145 * releasable events on the list.
147 int dyn_events_release_all(struct dyn_event_operations *type)
149 struct dyn_event *ev, *tmp;
152 mutex_lock(&event_mutex);
153 for_each_dyn_event(ev) {
154 if (type && ev->ops != type)
156 if (ev->ops->is_busy(ev)) {
161 for_each_dyn_event_safe(ev, tmp) {
162 if (type && ev->ops != type)
164 ret = ev->ops->free(ev);
169 tracing_reset_all_online_cpus();
170 mutex_unlock(&event_mutex);
175 static int dyn_event_open(struct inode *inode, struct file *file)
179 ret = tracing_check_open_get_tr(NULL);
183 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
184 ret = dyn_events_release_all(NULL);
189 return seq_open(file, &dyn_event_seq_op);
192 static ssize_t dyn_event_write(struct file *file, const char __user *buffer,
193 size_t count, loff_t *ppos)
195 return trace_parse_run_command(file, buffer, count, ppos,
199 static const struct file_operations dynamic_events_ops = {
200 .owner = THIS_MODULE,
201 .open = dyn_event_open,
204 .release = seq_release,
205 .write = dyn_event_write,
208 /* Make a tracefs interface for controlling dynamic events */
209 static __init int init_dynamic_event(void)
211 struct dentry *d_tracer;
212 struct dentry *entry;
214 d_tracer = tracing_init_dentry();
215 if (IS_ERR(d_tracer))
218 entry = tracefs_create_file("dynamic_events", 0644, d_tracer,
219 NULL, &dynamic_events_ops);
221 /* Event list interface */
223 pr_warn("Could not create tracefs 'dynamic_events' entry\n");
227 fs_initcall(init_dynamic_event);