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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_output.h" /* for trace_event_sem */
17#include "trace_dynevent.h"
18
19static DEFINE_MUTEX(dyn_event_ops_mutex);
20static LIST_HEAD(dyn_event_ops_list);
21
22bool trace_event_dyn_try_get_ref(struct trace_event_call *dyn_call)
23{
24 struct trace_event_call *call;
25 bool ret = false;
26
27 if (WARN_ON_ONCE(!(dyn_call->flags & TRACE_EVENT_FL_DYNAMIC)))
28 return false;
29
30 down_read(&trace_event_sem);
31 list_for_each_entry(call, &ftrace_events, list) {
32 if (call == dyn_call) {
33 atomic_inc(&dyn_call->refcnt);
34 ret = true;
35 }
36 }
37 up_read(&trace_event_sem);
38 return ret;
39}
40
41void trace_event_dyn_put_ref(struct trace_event_call *call)
42{
43 if (WARN_ON_ONCE(!(call->flags & TRACE_EVENT_FL_DYNAMIC)))
44 return;
45
46 if (WARN_ON_ONCE(atomic_read(&call->refcnt) <= 0)) {
47 atomic_set(&call->refcnt, 0);
48 return;
49 }
50
51 atomic_dec(&call->refcnt);
52}
53
54bool trace_event_dyn_busy(struct trace_event_call *call)
55{
56 return atomic_read(&call->refcnt) != 0;
57}
58
59int dyn_event_register(struct dyn_event_operations *ops)
60{
61 if (!ops || !ops->create || !ops->show || !ops->is_busy ||
62 !ops->free || !ops->match)
63 return -EINVAL;
64
65 INIT_LIST_HEAD(&ops->list);
66 mutex_lock(&dyn_event_ops_mutex);
67 list_add_tail(&ops->list, &dyn_event_ops_list);
68 mutex_unlock(&dyn_event_ops_mutex);
69 return 0;
70}
71
72int dyn_event_release(const char *raw_command, struct dyn_event_operations *type)
73{
74 struct dyn_event *pos, *n;
75 char *system = NULL, *event, *p;
76 int argc, ret = -ENOENT;
77 char **argv;
78
79 argv = argv_split(GFP_KERNEL, raw_command, &argc);
80 if (!argv)
81 return -ENOMEM;
82
83 if (argv[0][0] == '-') {
84 if (argv[0][1] != ':') {
85 ret = -EINVAL;
86 goto out;
87 }
88 event = &argv[0][2];
89 } else {
90 event = strchr(argv[0], ':');
91 if (!event) {
92 ret = -EINVAL;
93 goto out;
94 }
95 event++;
96 }
97
98 p = strchr(event, '/');
99 if (p) {
100 system = event;
101 event = p + 1;
102 *p = '\0';
103 }
104 if (!system && event[0] == '\0') {
105 ret = -EINVAL;
106 goto out;
107 }
108
109 mutex_lock(&event_mutex);
110 for_each_dyn_event_safe(pos, n) {
111 if (type && type != pos->ops)
112 continue;
113 if (!pos->ops->match(system, event,
114 argc - 1, (const char **)argv + 1, pos))
115 continue;
116
117 ret = pos->ops->free(pos);
118 if (ret)
119 break;
120 }
121 tracing_reset_all_online_cpus();
122 mutex_unlock(&event_mutex);
123out:
124 argv_free(argv);
125 return ret;
126}
127
128static int create_dyn_event(const char *raw_command)
129{
130 struct dyn_event_operations *ops;
131 int ret = -ENODEV;
132
133 if (raw_command[0] == '-' || raw_command[0] == '!')
134 return dyn_event_release(raw_command, NULL);
135
136 mutex_lock(&dyn_event_ops_mutex);
137 list_for_each_entry(ops, &dyn_event_ops_list, list) {
138 ret = ops->create(raw_command);
139 if (!ret || ret != -ECANCELED)
140 break;
141 }
142 mutex_unlock(&dyn_event_ops_mutex);
143 if (ret == -ECANCELED)
144 ret = -EINVAL;
145
146 return ret;
147}
148
149/* Protected by event_mutex */
150LIST_HEAD(dyn_event_list);
151
152void *dyn_event_seq_start(struct seq_file *m, loff_t *pos)
153{
154 mutex_lock(&event_mutex);
155 return seq_list_start(&dyn_event_list, *pos);
156}
157
158void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
159{
160 return seq_list_next(v, &dyn_event_list, pos);
161}
162
163void dyn_event_seq_stop(struct seq_file *m, void *v)
164{
165 mutex_unlock(&event_mutex);
166}
167
168static int dyn_event_seq_show(struct seq_file *m, void *v)
169{
170 struct dyn_event *ev = v;
171
172 if (ev && ev->ops)
173 return ev->ops->show(m, ev);
174
175 return 0;
176}
177
178static const struct seq_operations dyn_event_seq_op = {
179 .start = dyn_event_seq_start,
180 .next = dyn_event_seq_next,
181 .stop = dyn_event_seq_stop,
182 .show = dyn_event_seq_show
183};
184
185/*
186 * dyn_events_release_all - Release all specific events
187 * @type: the dyn_event_operations * which filters releasing events
188 *
189 * This releases all events which ->ops matches @type. If @type is NULL,
190 * all events are released.
191 * Return -EBUSY if any of them are in use, and return other errors when
192 * it failed to free the given event. Except for -EBUSY, event releasing
193 * process will be aborted at that point and there may be some other
194 * releasable events on the list.
195 */
196int dyn_events_release_all(struct dyn_event_operations *type)
197{
198 struct dyn_event *ev, *tmp;
199 int ret = 0;
200
201 mutex_lock(&event_mutex);
202 for_each_dyn_event(ev) {
203 if (type && ev->ops != type)
204 continue;
205 if (ev->ops->is_busy(ev)) {
206 ret = -EBUSY;
207 goto out;
208 }
209 }
210 for_each_dyn_event_safe(ev, tmp) {
211 if (type && ev->ops != type)
212 continue;
213 ret = ev->ops->free(ev);
214 if (ret)
215 break;
216 }
217out:
218 tracing_reset_all_online_cpus();
219 mutex_unlock(&event_mutex);
220
221 return ret;
222}
223
224static int dyn_event_open(struct inode *inode, struct file *file)
225{
226 int ret;
227
228 ret = tracing_check_open_get_tr(NULL);
229 if (ret)
230 return ret;
231
232 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
233 ret = dyn_events_release_all(NULL);
234 if (ret < 0)
235 return ret;
236 }
237
238 return seq_open(file, &dyn_event_seq_op);
239}
240
241static ssize_t dyn_event_write(struct file *file, const char __user *buffer,
242 size_t count, loff_t *ppos)
243{
244 return trace_parse_run_command(file, buffer, count, ppos,
245 create_dyn_event);
246}
247
248static const struct file_operations dynamic_events_ops = {
249 .owner = THIS_MODULE,
250 .open = dyn_event_open,
251 .read = seq_read,
252 .llseek = seq_lseek,
253 .release = seq_release,
254 .write = dyn_event_write,
255};
256
257/* Make a tracefs interface for controlling dynamic events */
258static __init int init_dynamic_event(void)
259{
260 int ret;
261
262 ret = tracing_init_dentry();
263 if (ret)
264 return 0;
265
266 trace_create_file("dynamic_events", TRACE_MODE_WRITE, NULL,
267 NULL, &dynamic_events_ops);
268
269 return 0;
270}
271fs_initcall(init_dynamic_event);
272
273/**
274 * dynevent_arg_add - Add an arg to a dynevent_cmd
275 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
276 * @arg: The argument to append to the current cmd
277 * @check_arg: An (optional) pointer to a function checking arg sanity
278 *
279 * Append an argument to a dynevent_cmd. The argument string will be
280 * appended to the current cmd string, followed by a separator, if
281 * applicable. Before the argument is added, the @check_arg function,
282 * if present, will be used to check the sanity of the current arg
283 * string.
284 *
285 * The cmd string and separator should be set using the
286 * dynevent_arg_init() before any arguments are added using this
287 * function.
288 *
289 * Return: 0 if successful, error otherwise.
290 */
291int dynevent_arg_add(struct dynevent_cmd *cmd,
292 struct dynevent_arg *arg,
293 dynevent_check_arg_fn_t check_arg)
294{
295 int ret = 0;
296
297 if (check_arg) {
298 ret = check_arg(arg);
299 if (ret)
300 return ret;
301 }
302
303 ret = seq_buf_printf(&cmd->seq, " %s%c", arg->str, arg->separator);
304 if (ret) {
305 pr_err("String is too long: %s%c\n", arg->str, arg->separator);
306 return -E2BIG;
307 }
308
309 return ret;
310}
311
312/**
313 * dynevent_arg_pair_add - Add an arg pair to a dynevent_cmd
314 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
315 * @arg_pair: The argument pair to append to the current cmd
316 * @check_arg: An (optional) pointer to a function checking arg sanity
317 *
318 * Append an argument pair to a dynevent_cmd. An argument pair
319 * consists of a left-hand-side argument and a right-hand-side
320 * argument separated by an operator, which can be whitespace, all
321 * followed by a separator, if applicable. This can be used to add
322 * arguments of the form 'type variable_name;' or 'x+y'.
323 *
324 * The lhs argument string will be appended to the current cmd string,
325 * followed by an operator, if applicable, followed by the rhs string,
326 * followed finally by a separator, if applicable. Before the
327 * argument is added, the @check_arg function, if present, will be
328 * used to check the sanity of the current arg strings.
329 *
330 * The cmd strings, operator, and separator should be set using the
331 * dynevent_arg_pair_init() before any arguments are added using this
332 * function.
333 *
334 * Return: 0 if successful, error otherwise.
335 */
336int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
337 struct dynevent_arg_pair *arg_pair,
338 dynevent_check_arg_fn_t check_arg)
339{
340 int ret = 0;
341
342 if (check_arg) {
343 ret = check_arg(arg_pair);
344 if (ret)
345 return ret;
346 }
347
348 ret = seq_buf_printf(&cmd->seq, " %s%c%s%c", arg_pair->lhs,
349 arg_pair->operator, arg_pair->rhs,
350 arg_pair->separator);
351 if (ret) {
352 pr_err("field string is too long: %s%c%s%c\n", arg_pair->lhs,
353 arg_pair->operator, arg_pair->rhs,
354 arg_pair->separator);
355 return -E2BIG;
356 }
357
358 return ret;
359}
360
361/**
362 * dynevent_str_add - Add a string to a dynevent_cmd
363 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
364 * @str: The string to append to the current cmd
365 *
366 * Append a string to a dynevent_cmd. The string will be appended to
367 * the current cmd string as-is, with nothing prepended or appended.
368 *
369 * Return: 0 if successful, error otherwise.
370 */
371int dynevent_str_add(struct dynevent_cmd *cmd, const char *str)
372{
373 int ret = 0;
374
375 ret = seq_buf_puts(&cmd->seq, str);
376 if (ret) {
377 pr_err("String is too long: %s\n", str);
378 return -E2BIG;
379 }
380
381 return ret;
382}
383
384/**
385 * dynevent_cmd_init - Initialize a dynevent_cmd object
386 * @cmd: A pointer to the dynevent_cmd struct representing the cmd
387 * @buf: A pointer to the buffer to generate the command into
388 * @maxlen: The length of the buffer the command will be generated into
389 * @type: The type of the cmd, checked against further operations
390 * @run_command: The type-specific function that will actually run the command
391 *
392 * Initialize a dynevent_cmd. A dynevent_cmd is used to build up and
393 * run dynamic event creation commands, such as commands for creating
394 * synthetic and kprobe events. Before calling any of the functions
395 * used to build the command, a dynevent_cmd object should be
396 * instantiated and initialized using this function.
397 *
398 * The initialization sets things up by saving a pointer to the
399 * user-supplied buffer and its length via the @buf and @maxlen
400 * params, and by saving the cmd-specific @type and @run_command
401 * params which are used to check subsequent dynevent_cmd operations
402 * and actually run the command when complete.
403 */
404void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
405 enum dynevent_type type,
406 dynevent_create_fn_t run_command)
407{
408 memset(cmd, '\0', sizeof(*cmd));
409
410 seq_buf_init(&cmd->seq, buf, maxlen);
411 cmd->type = type;
412 cmd->run_command = run_command;
413}
414
415/**
416 * dynevent_arg_init - Initialize a dynevent_arg object
417 * @arg: A pointer to the dynevent_arg struct representing the arg
418 * @separator: An (optional) separator, appended after adding the arg
419 *
420 * Initialize a dynevent_arg object. A dynevent_arg represents an
421 * object used to append single arguments to the current command
422 * string. After the arg string is successfully appended to the
423 * command string, the optional @separator is appended. If no
424 * separator was specified when initializing the arg, a space will be
425 * appended.
426 */
427void dynevent_arg_init(struct dynevent_arg *arg,
428 char separator)
429{
430 memset(arg, '\0', sizeof(*arg));
431
432 if (!separator)
433 separator = ' ';
434 arg->separator = separator;
435}
436
437/**
438 * dynevent_arg_pair_init - Initialize a dynevent_arg_pair object
439 * @arg_pair: A pointer to the dynevent_arg_pair struct representing the arg
440 * @operator: An (optional) operator, appended after adding the first arg
441 * @separator: An (optional) separator, appended after adding the second arg
442 *
443 * Initialize a dynevent_arg_pair object. A dynevent_arg_pair
444 * represents an object used to append argument pairs such as 'type
445 * variable_name;' or 'x+y' to the current command string. An
446 * argument pair consists of a left-hand-side argument and a
447 * right-hand-side argument separated by an operator, which can be
448 * whitespace, all followed by a separator, if applicable. After the
449 * first arg string is successfully appended to the command string,
450 * the optional @operator is appended, followed by the second arg and
451 * optional @separator. If no separator was specified when
452 * initializing the arg, a space will be appended.
453 */
454void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
455 char operator, char separator)
456{
457 memset(arg_pair, '\0', sizeof(*arg_pair));
458
459 if (!operator)
460 operator = ' ';
461 arg_pair->operator = operator;
462
463 if (!separator)
464 separator = ' ';
465 arg_pair->separator = separator;
466}
467
468/**
469 * dynevent_create - Create the dynamic event contained in dynevent_cmd
470 * @cmd: The dynevent_cmd object containing the dynamic event creation command
471 *
472 * Once a dynevent_cmd object has been successfully built up via the
473 * dynevent_cmd_init(), dynevent_arg_add() and dynevent_arg_pair_add()
474 * functions, this function runs the final command to actually create
475 * the event.
476 *
477 * Return: 0 if the event was successfully created, error otherwise.
478 */
479int dynevent_create(struct dynevent_cmd *cmd)
480{
481 return cmd->run_command(cmd);
482}
483EXPORT_SYMBOL_GPL(dynevent_create);
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
18static DEFINE_MUTEX(dyn_event_ops_mutex);
19static LIST_HEAD(dyn_event_ops_list);
20
21int 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
34int dyn_event_release(const char *raw_command, struct dyn_event_operations *type)
35{
36 struct dyn_event *pos, *n;
37 char *system = NULL, *event, *p;
38 int argc, ret = -ENOENT;
39 char **argv;
40
41 argv = argv_split(GFP_KERNEL, raw_command, &argc);
42 if (!argv)
43 return -ENOMEM;
44
45 if (argv[0][0] == '-') {
46 if (argv[0][1] != ':') {
47 ret = -EINVAL;
48 goto out;
49 }
50 event = &argv[0][2];
51 } else {
52 event = strchr(argv[0], ':');
53 if (!event) {
54 ret = -EINVAL;
55 goto out;
56 }
57 event++;
58 }
59
60 p = strchr(event, '/');
61 if (p) {
62 system = event;
63 event = p + 1;
64 *p = '\0';
65 }
66 if (event[0] == '\0') {
67 ret = -EINVAL;
68 goto out;
69 }
70
71 mutex_lock(&event_mutex);
72 for_each_dyn_event_safe(pos, n) {
73 if (type && type != pos->ops)
74 continue;
75 if (!pos->ops->match(system, event,
76 argc - 1, (const char **)argv + 1, pos))
77 continue;
78
79 ret = pos->ops->free(pos);
80 if (ret)
81 break;
82 }
83 mutex_unlock(&event_mutex);
84out:
85 argv_free(argv);
86 return ret;
87}
88
89static int create_dyn_event(const char *raw_command)
90{
91 struct dyn_event_operations *ops;
92 int ret = -ENODEV;
93
94 if (raw_command[0] == '-' || raw_command[0] == '!')
95 return dyn_event_release(raw_command, NULL);
96
97 mutex_lock(&dyn_event_ops_mutex);
98 list_for_each_entry(ops, &dyn_event_ops_list, list) {
99 ret = ops->create(raw_command);
100 if (!ret || ret != -ECANCELED)
101 break;
102 }
103 mutex_unlock(&dyn_event_ops_mutex);
104 if (ret == -ECANCELED)
105 ret = -EINVAL;
106
107 return ret;
108}
109
110/* Protected by event_mutex */
111LIST_HEAD(dyn_event_list);
112
113void *dyn_event_seq_start(struct seq_file *m, loff_t *pos)
114{
115 mutex_lock(&event_mutex);
116 return seq_list_start(&dyn_event_list, *pos);
117}
118
119void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
120{
121 return seq_list_next(v, &dyn_event_list, pos);
122}
123
124void dyn_event_seq_stop(struct seq_file *m, void *v)
125{
126 mutex_unlock(&event_mutex);
127}
128
129static int dyn_event_seq_show(struct seq_file *m, void *v)
130{
131 struct dyn_event *ev = v;
132
133 if (ev && ev->ops)
134 return ev->ops->show(m, ev);
135
136 return 0;
137}
138
139static const struct seq_operations dyn_event_seq_op = {
140 .start = dyn_event_seq_start,
141 .next = dyn_event_seq_next,
142 .stop = dyn_event_seq_stop,
143 .show = dyn_event_seq_show
144};
145
146/*
147 * dyn_events_release_all - Release all specific events
148 * @type: the dyn_event_operations * which filters releasing events
149 *
150 * This releases all events which ->ops matches @type. If @type is NULL,
151 * all events are released.
152 * Return -EBUSY if any of them are in use, and return other errors when
153 * it failed to free the given event. Except for -EBUSY, event releasing
154 * process will be aborted at that point and there may be some other
155 * releasable events on the list.
156 */
157int dyn_events_release_all(struct dyn_event_operations *type)
158{
159 struct dyn_event *ev, *tmp;
160 int ret = 0;
161
162 mutex_lock(&event_mutex);
163 for_each_dyn_event(ev) {
164 if (type && ev->ops != type)
165 continue;
166 if (ev->ops->is_busy(ev)) {
167 ret = -EBUSY;
168 goto out;
169 }
170 }
171 for_each_dyn_event_safe(ev, tmp) {
172 if (type && ev->ops != type)
173 continue;
174 ret = ev->ops->free(ev);
175 if (ret)
176 break;
177 }
178out:
179 mutex_unlock(&event_mutex);
180
181 return ret;
182}
183
184static int dyn_event_open(struct inode *inode, struct file *file)
185{
186 int ret;
187
188 ret = tracing_check_open_get_tr(NULL);
189 if (ret)
190 return ret;
191
192 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
193 ret = dyn_events_release_all(NULL);
194 if (ret < 0)
195 return ret;
196 }
197
198 return seq_open(file, &dyn_event_seq_op);
199}
200
201static ssize_t dyn_event_write(struct file *file, const char __user *buffer,
202 size_t count, loff_t *ppos)
203{
204 return trace_parse_run_command(file, buffer, count, ppos,
205 create_dyn_event);
206}
207
208static const struct file_operations dynamic_events_ops = {
209 .owner = THIS_MODULE,
210 .open = dyn_event_open,
211 .read = seq_read,
212 .llseek = seq_lseek,
213 .release = seq_release,
214 .write = dyn_event_write,
215};
216
217/* Make a tracefs interface for controlling dynamic events */
218static __init int init_dynamic_event(void)
219{
220 struct dentry *entry;
221 int ret;
222
223 ret = tracing_init_dentry();
224 if (ret)
225 return 0;
226
227 entry = tracefs_create_file("dynamic_events", 0644, NULL,
228 NULL, &dynamic_events_ops);
229
230 /* Event list interface */
231 if (!entry)
232 pr_warn("Could not create tracefs 'dynamic_events' entry\n");
233
234 return 0;
235}
236fs_initcall(init_dynamic_event);
237
238/**
239 * dynevent_arg_add - Add an arg to a dynevent_cmd
240 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
241 * @arg: The argument to append to the current cmd
242 * @check_arg: An (optional) pointer to a function checking arg sanity
243 *
244 * Append an argument to a dynevent_cmd. The argument string will be
245 * appended to the current cmd string, followed by a separator, if
246 * applicable. Before the argument is added, the @check_arg function,
247 * if present, will be used to check the sanity of the current arg
248 * string.
249 *
250 * The cmd string and separator should be set using the
251 * dynevent_arg_init() before any arguments are added using this
252 * function.
253 *
254 * Return: 0 if successful, error otherwise.
255 */
256int dynevent_arg_add(struct dynevent_cmd *cmd,
257 struct dynevent_arg *arg,
258 dynevent_check_arg_fn_t check_arg)
259{
260 int ret = 0;
261
262 if (check_arg) {
263 ret = check_arg(arg);
264 if (ret)
265 return ret;
266 }
267
268 ret = seq_buf_printf(&cmd->seq, " %s%c", arg->str, arg->separator);
269 if (ret) {
270 pr_err("String is too long: %s%c\n", arg->str, arg->separator);
271 return -E2BIG;
272 }
273
274 return ret;
275}
276
277/**
278 * dynevent_arg_pair_add - Add an arg pair to a dynevent_cmd
279 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
280 * @arg_pair: The argument pair to append to the current cmd
281 * @check_arg: An (optional) pointer to a function checking arg sanity
282 *
283 * Append an argument pair to a dynevent_cmd. An argument pair
284 * consists of a left-hand-side argument and a right-hand-side
285 * argument separated by an operator, which can be whitespace, all
286 * followed by a separator, if applicable. This can be used to add
287 * arguments of the form 'type variable_name;' or 'x+y'.
288 *
289 * The lhs argument string will be appended to the current cmd string,
290 * followed by an operator, if applicable, followed by the rhs string,
291 * followed finally by a separator, if applicable. Before the
292 * argument is added, the @check_arg function, if present, will be
293 * used to check the sanity of the current arg strings.
294 *
295 * The cmd strings, operator, and separator should be set using the
296 * dynevent_arg_pair_init() before any arguments are added using this
297 * function.
298 *
299 * Return: 0 if successful, error otherwise.
300 */
301int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
302 struct dynevent_arg_pair *arg_pair,
303 dynevent_check_arg_fn_t check_arg)
304{
305 int ret = 0;
306
307 if (check_arg) {
308 ret = check_arg(arg_pair);
309 if (ret)
310 return ret;
311 }
312
313 ret = seq_buf_printf(&cmd->seq, " %s%c%s%c", arg_pair->lhs,
314 arg_pair->operator, arg_pair->rhs,
315 arg_pair->separator);
316 if (ret) {
317 pr_err("field string is too long: %s%c%s%c\n", arg_pair->lhs,
318 arg_pair->operator, arg_pair->rhs,
319 arg_pair->separator);
320 return -E2BIG;
321 }
322
323 return ret;
324}
325
326/**
327 * dynevent_str_add - Add a string to a dynevent_cmd
328 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
329 * @str: The string to append to the current cmd
330 *
331 * Append a string to a dynevent_cmd. The string will be appended to
332 * the current cmd string as-is, with nothing prepended or appended.
333 *
334 * Return: 0 if successful, error otherwise.
335 */
336int dynevent_str_add(struct dynevent_cmd *cmd, const char *str)
337{
338 int ret = 0;
339
340 ret = seq_buf_puts(&cmd->seq, str);
341 if (ret) {
342 pr_err("String is too long: %s\n", str);
343 return -E2BIG;
344 }
345
346 return ret;
347}
348
349/**
350 * dynevent_cmd_init - Initialize a dynevent_cmd object
351 * @cmd: A pointer to the dynevent_cmd struct representing the cmd
352 * @buf: A pointer to the buffer to generate the command into
353 * @maxlen: The length of the buffer the command will be generated into
354 * @type: The type of the cmd, checked against further operations
355 * @run_command: The type-specific function that will actually run the command
356 *
357 * Initialize a dynevent_cmd. A dynevent_cmd is used to build up and
358 * run dynamic event creation commands, such as commands for creating
359 * synthetic and kprobe events. Before calling any of the functions
360 * used to build the command, a dynevent_cmd object should be
361 * instantiated and initialized using this function.
362 *
363 * The initialization sets things up by saving a pointer to the
364 * user-supplied buffer and its length via the @buf and @maxlen
365 * params, and by saving the cmd-specific @type and @run_command
366 * params which are used to check subsequent dynevent_cmd operations
367 * and actually run the command when complete.
368 */
369void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
370 enum dynevent_type type,
371 dynevent_create_fn_t run_command)
372{
373 memset(cmd, '\0', sizeof(*cmd));
374
375 seq_buf_init(&cmd->seq, buf, maxlen);
376 cmd->type = type;
377 cmd->run_command = run_command;
378}
379
380/**
381 * dynevent_arg_init - Initialize a dynevent_arg object
382 * @arg: A pointer to the dynevent_arg struct representing the arg
383 * @separator: An (optional) separator, appended after adding the arg
384 *
385 * Initialize a dynevent_arg object. A dynevent_arg represents an
386 * object used to append single arguments to the current command
387 * string. After the arg string is successfully appended to the
388 * command string, the optional @separator is appended. If no
389 * separator was specified when initializing the arg, a space will be
390 * appended.
391 */
392void dynevent_arg_init(struct dynevent_arg *arg,
393 char separator)
394{
395 memset(arg, '\0', sizeof(*arg));
396
397 if (!separator)
398 separator = ' ';
399 arg->separator = separator;
400}
401
402/**
403 * dynevent_arg_pair_init - Initialize a dynevent_arg_pair object
404 * @arg_pair: A pointer to the dynevent_arg_pair struct representing the arg
405 * @operator: An (optional) operator, appended after adding the first arg
406 * @separator: An (optional) separator, appended after adding the second arg
407 *
408 * Initialize a dynevent_arg_pair object. A dynevent_arg_pair
409 * represents an object used to append argument pairs such as 'type
410 * variable_name;' or 'x+y' to the current command string. An
411 * argument pair consists of a left-hand-side argument and a
412 * right-hand-side argument separated by an operator, which can be
413 * whitespace, all followed by a separator, if applicable. After the
414 * first arg string is successfully appended to the command string,
415 * the optional @operator is appended, followed by the second arg and
416 * optional @separator. If no separator was specified when
417 * initializing the arg, a space will be appended.
418 */
419void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
420 char operator, char separator)
421{
422 memset(arg_pair, '\0', sizeof(*arg_pair));
423
424 if (!operator)
425 operator = ' ';
426 arg_pair->operator = operator;
427
428 if (!separator)
429 separator = ' ';
430 arg_pair->separator = separator;
431}
432
433/**
434 * dynevent_create - Create the dynamic event contained in dynevent_cmd
435 * @cmd: The dynevent_cmd object containing the dynamic event creation command
436 *
437 * Once a dynevent_cmd object has been successfully built up via the
438 * dynevent_cmd_init(), dynevent_arg_add() and dynevent_arg_pair_add()
439 * functions, this function runs the final command to actually create
440 * the event.
441 *
442 * Return: 0 if the event was successfully created, error otherwise.
443 */
444int dynevent_create(struct dynevent_cmd *cmd)
445{
446 return cmd->run_command(cmd);
447}
448EXPORT_SYMBOL_GPL(dynevent_create);