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5448d44c MH |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Generic dynamic event control interface | |
4 | * | |
5 | * Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org> | |
6 | */ | |
7 | ||
8 | #include <linux/debugfs.h> | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/list.h> | |
11 | #include <linux/mm.h> | |
12 | #include <linux/mutex.h> | |
13 | #include <linux/tracefs.h> | |
14 | ||
15 | #include "trace.h" | |
16 | #include "trace_dynevent.h" | |
17 | ||
18 | static DEFINE_MUTEX(dyn_event_ops_mutex); | |
19 | static LIST_HEAD(dyn_event_ops_list); | |
20 | ||
21 | int dyn_event_register(struct dyn_event_operations *ops) | |
22 | { | |
23 | if (!ops || !ops->create || !ops->show || !ops->is_busy || | |
24 | !ops->free || !ops->match) | |
25 | return -EINVAL; | |
26 | ||
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); | |
31 | return 0; | |
32 | } | |
33 | ||
34 | int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type) | |
35 | { | |
36 | struct dyn_event *pos, *n; | |
37 | char *system = NULL, *event, *p; | |
38 | int ret = -ENOENT; | |
39 | ||
1ce25e9f MH |
40 | if (argv[0][0] == '-') { |
41 | if (argv[0][1] != ':') | |
42 | return -EINVAL; | |
43 | event = &argv[0][2]; | |
44 | } else { | |
45 | event = strchr(argv[0], ':'); | |
46 | if (!event) | |
47 | return -EINVAL; | |
48 | event++; | |
49 | } | |
5448d44c | 50 | |
5448d44c MH |
51 | p = strchr(event, '/'); |
52 | if (p) { | |
53 | system = event; | |
54 | event = p + 1; | |
55 | *p = '\0'; | |
56 | } | |
57 | if (event[0] == '\0') | |
58 | return -EINVAL; | |
59 | ||
60 | mutex_lock(&event_mutex); | |
61 | for_each_dyn_event_safe(pos, n) { | |
62 | if (type && type != pos->ops) | |
63 | continue; | |
64 | if (pos->ops->match(system, event, pos)) { | |
65 | ret = pos->ops->free(pos); | |
66 | break; | |
67 | } | |
68 | } | |
69 | mutex_unlock(&event_mutex); | |
70 | ||
71 | return ret; | |
72 | } | |
73 | ||
74 | static int create_dyn_event(int argc, char **argv) | |
75 | { | |
76 | struct dyn_event_operations *ops; | |
3dee10da | 77 | int ret = -ENODEV; |
5448d44c | 78 | |
1ce25e9f | 79 | if (argv[0][0] == '-' || argv[0][0] == '!') |
5448d44c MH |
80 | return dyn_event_release(argc, argv, NULL); |
81 | ||
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) | |
86 | break; | |
87 | } | |
88 | mutex_unlock(&dyn_event_ops_mutex); | |
89 | if (ret == -ECANCELED) | |
90 | ret = -EINVAL; | |
91 | ||
92 | return ret; | |
93 | } | |
94 | ||
95 | /* Protected by event_mutex */ | |
96 | LIST_HEAD(dyn_event_list); | |
97 | ||
98 | void *dyn_event_seq_start(struct seq_file *m, loff_t *pos) | |
99 | { | |
100 | mutex_lock(&event_mutex); | |
101 | return seq_list_start(&dyn_event_list, *pos); | |
102 | } | |
103 | ||
104 | void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos) | |
105 | { | |
106 | return seq_list_next(v, &dyn_event_list, pos); | |
107 | } | |
108 | ||
109 | void dyn_event_seq_stop(struct seq_file *m, void *v) | |
110 | { | |
111 | mutex_unlock(&event_mutex); | |
112 | } | |
113 | ||
114 | static int dyn_event_seq_show(struct seq_file *m, void *v) | |
115 | { | |
116 | struct dyn_event *ev = v; | |
117 | ||
118 | if (ev && ev->ops) | |
119 | return ev->ops->show(m, ev); | |
120 | ||
121 | return 0; | |
122 | } | |
123 | ||
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 | |
129 | }; | |
130 | ||
131 | /* | |
132 | * dyn_events_release_all - Release all specific events | |
133 | * @type: the dyn_event_operations * which filters releasing events | |
134 | * | |
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. | |
141 | */ | |
142 | int dyn_events_release_all(struct dyn_event_operations *type) | |
143 | { | |
144 | struct dyn_event *ev, *tmp; | |
145 | int ret = 0; | |
146 | ||
147 | mutex_lock(&event_mutex); | |
148 | for_each_dyn_event(ev) { | |
149 | if (type && ev->ops != type) | |
150 | continue; | |
151 | if (ev->ops->is_busy(ev)) { | |
152 | ret = -EBUSY; | |
153 | goto out; | |
154 | } | |
155 | } | |
156 | for_each_dyn_event_safe(ev, tmp) { | |
157 | if (type && ev->ops != type) | |
158 | continue; | |
159 | ret = ev->ops->free(ev); | |
160 | if (ret) | |
161 | break; | |
162 | } | |
163 | out: | |
164 | mutex_unlock(&event_mutex); | |
165 | ||
166 | return ret; | |
167 | } | |
168 | ||
169 | static int dyn_event_open(struct inode *inode, struct file *file) | |
170 | { | |
171 | int ret; | |
172 | ||
173 | if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) { | |
174 | ret = dyn_events_release_all(NULL); | |
175 | if (ret < 0) | |
176 | return ret; | |
177 | } | |
178 | ||
179 | return seq_open(file, &dyn_event_seq_op); | |
180 | } | |
181 | ||
182 | static ssize_t dyn_event_write(struct file *file, const char __user *buffer, | |
183 | size_t count, loff_t *ppos) | |
184 | { | |
185 | return trace_parse_run_command(file, buffer, count, ppos, | |
186 | create_dyn_event); | |
187 | } | |
188 | ||
189 | static const struct file_operations dynamic_events_ops = { | |
190 | .owner = THIS_MODULE, | |
191 | .open = dyn_event_open, | |
192 | .read = seq_read, | |
193 | .llseek = seq_lseek, | |
194 | .release = seq_release, | |
195 | .write = dyn_event_write, | |
196 | }; | |
197 | ||
198 | /* Make a tracefs interface for controlling dynamic events */ | |
199 | static __init int init_dynamic_event(void) | |
200 | { | |
201 | struct dentry *d_tracer; | |
202 | struct dentry *entry; | |
203 | ||
204 | d_tracer = tracing_init_dentry(); | |
205 | if (IS_ERR(d_tracer)) | |
206 | return 0; | |
207 | ||
208 | entry = tracefs_create_file("dynamic_events", 0644, d_tracer, | |
209 | NULL, &dynamic_events_ops); | |
210 | ||
211 | /* Event list interface */ | |
212 | if (!entry) | |
213 | pr_warn("Could not create tracefs 'dynamic_events' entry\n"); | |
214 | ||
215 | return 0; | |
216 | } | |
217 | fs_initcall(init_dynamic_event); |