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], ':');
51 p
= strchr(event
, '/');
60 mutex_lock(&event_mutex
);
61 for_each_dyn_event_safe(pos
, n
) {
62 if (type
&& type
!= pos
->ops
)
64 if (pos
->ops
->match(system
, event
, pos
)) {
65 ret
= pos
->ops
->free(pos
);
69 mutex_unlock(&event_mutex
);
74 static int create_dyn_event(int argc
, char **argv
)
76 struct dyn_event_operations
*ops
;
79 if (argv
[0][0] == '-' || argv
[0][0] == '!')
80 return dyn_event_release(argc
, argv
, NULL
);
82 mutex_lock(&dyn_event_ops_mutex
);
83 list_for_each_entry(ops
, &dyn_event_ops_list
, list
) {
84 ret
= ops
->create(argc
, (const char **)argv
);
85 if (!ret
|| ret
!= -ECANCELED
)
88 mutex_unlock(&dyn_event_ops_mutex
);
89 if (ret
== -ECANCELED
)
95 /* Protected by event_mutex */
96 LIST_HEAD(dyn_event_list
);
98 void *dyn_event_seq_start(struct seq_file
*m
, loff_t
*pos
)
100 mutex_lock(&event_mutex
);
101 return seq_list_start(&dyn_event_list
, *pos
);
104 void *dyn_event_seq_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
106 return seq_list_next(v
, &dyn_event_list
, pos
);
109 void dyn_event_seq_stop(struct seq_file
*m
, void *v
)
111 mutex_unlock(&event_mutex
);
114 static int dyn_event_seq_show(struct seq_file
*m
, void *v
)
116 struct dyn_event
*ev
= v
;
119 return ev
->ops
->show(m
, ev
);
124 static const struct seq_operations dyn_event_seq_op
= {
125 .start
= dyn_event_seq_start
,
126 .next
= dyn_event_seq_next
,
127 .stop
= dyn_event_seq_stop
,
128 .show
= dyn_event_seq_show
132 * dyn_events_release_all - Release all specific events
133 * @type: the dyn_event_operations * which filters releasing events
135 * This releases all events which ->ops matches @type. If @type is NULL,
136 * all events are released.
137 * Return -EBUSY if any of them are in use, and return other errors when
138 * it failed to free the given event. Except for -EBUSY, event releasing
139 * process will be aborted at that point and there may be some other
140 * releasable events on the list.
142 int dyn_events_release_all(struct dyn_event_operations
*type
)
144 struct dyn_event
*ev
, *tmp
;
147 mutex_lock(&event_mutex
);
148 for_each_dyn_event(ev
) {
149 if (type
&& ev
->ops
!= type
)
151 if (ev
->ops
->is_busy(ev
)) {
156 for_each_dyn_event_safe(ev
, tmp
) {
157 if (type
&& ev
->ops
!= type
)
159 ret
= ev
->ops
->free(ev
);
164 mutex_unlock(&event_mutex
);
169 static int dyn_event_open(struct inode
*inode
, struct file
*file
)
173 if ((file
->f_mode
& FMODE_WRITE
) && (file
->f_flags
& O_TRUNC
)) {
174 ret
= dyn_events_release_all(NULL
);
179 return seq_open(file
, &dyn_event_seq_op
);
182 static ssize_t
dyn_event_write(struct file
*file
, const char __user
*buffer
,
183 size_t count
, loff_t
*ppos
)
185 return trace_parse_run_command(file
, buffer
, count
, ppos
,
189 static const struct file_operations dynamic_events_ops
= {
190 .owner
= THIS_MODULE
,
191 .open
= dyn_event_open
,
194 .release
= seq_release
,
195 .write
= dyn_event_write
,
198 /* Make a tracefs interface for controlling dynamic events */
199 static __init
int init_dynamic_event(void)
201 struct dentry
*d_tracer
;
202 struct dentry
*entry
;
204 d_tracer
= tracing_init_dentry();
205 if (IS_ERR(d_tracer
))
208 entry
= tracefs_create_file("dynamic_events", 0644, d_tracer
,
209 NULL
, &dynamic_events_ops
);
211 /* Event list interface */
213 pr_warn("Could not create tracefs 'dynamic_events' entry\n");
217 fs_initcall(init_dynamic_event
);