xref: /linux/drivers/ptp/ptp_chardev.c (revision af2d6148d2a159e1a0862bce5a2c88c1618a2b27)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * PTP 1588 clock support - character device implementation.
4  *
5  * Copyright (C) 2010 OMICRON electronics GmbH
6  */
7 #include <linux/compat.h>
8 #include <linux/module.h>
9 #include <linux/posix-clock.h>
10 #include <linux/poll.h>
11 #include <linux/sched.h>
12 #include <linux/slab.h>
13 #include <linux/timekeeping.h>
14 #include <linux/debugfs.h>
15 
16 #include <linux/nospec.h>
17 
18 #include "ptp_private.h"
19 
20 static int ptp_disable_pinfunc(struct ptp_clock_info *ops,
21 			       enum ptp_pin_function func, unsigned int chan)
22 {
23 	struct ptp_clock_request rq;
24 	int err = 0;
25 
26 	memset(&rq, 0, sizeof(rq));
27 
28 	switch (func) {
29 	case PTP_PF_NONE:
30 		break;
31 	case PTP_PF_EXTTS:
32 		rq.type = PTP_CLK_REQ_EXTTS;
33 		rq.extts.index = chan;
34 		err = ops->enable(ops, &rq, 0);
35 		break;
36 	case PTP_PF_PEROUT:
37 		rq.type = PTP_CLK_REQ_PEROUT;
38 		rq.perout.index = chan;
39 		err = ops->enable(ops, &rq, 0);
40 		break;
41 	case PTP_PF_PHYSYNC:
42 		break;
43 	default:
44 		return -EINVAL;
45 	}
46 
47 	return err;
48 }
49 
50 int ptp_set_pinfunc(struct ptp_clock *ptp, unsigned int pin,
51 		    enum ptp_pin_function func, unsigned int chan)
52 {
53 	struct ptp_clock_info *info = ptp->info;
54 	struct ptp_pin_desc *pin1 = NULL, *pin2 = &info->pin_config[pin];
55 	unsigned int i;
56 
57 	/* Check to see if any other pin previously had this function. */
58 	for (i = 0; i < info->n_pins; i++) {
59 		if (info->pin_config[i].func == func &&
60 		    info->pin_config[i].chan == chan) {
61 			pin1 = &info->pin_config[i];
62 			break;
63 		}
64 	}
65 	if (pin1 && i == pin)
66 		return 0;
67 
68 	/* Check the desired function and channel. */
69 	switch (func) {
70 	case PTP_PF_NONE:
71 		break;
72 	case PTP_PF_EXTTS:
73 		if (chan >= info->n_ext_ts)
74 			return -EINVAL;
75 		break;
76 	case PTP_PF_PEROUT:
77 		if (chan >= info->n_per_out)
78 			return -EINVAL;
79 		break;
80 	case PTP_PF_PHYSYNC:
81 		if (chan != 0)
82 			return -EINVAL;
83 		break;
84 	default:
85 		return -EINVAL;
86 	}
87 
88 	if (info->verify(info, pin, func, chan)) {
89 		pr_err("driver cannot use function %u and channel %u on pin %u\n",
90 		       func, chan, pin);
91 		return -EOPNOTSUPP;
92 	}
93 
94 	/* Disable whatever function was previously assigned. */
95 	if (pin1) {
96 		ptp_disable_pinfunc(info, func, chan);
97 		pin1->func = PTP_PF_NONE;
98 		pin1->chan = 0;
99 	}
100 	ptp_disable_pinfunc(info, pin2->func, pin2->chan);
101 	pin2->func = func;
102 	pin2->chan = chan;
103 
104 	return 0;
105 }
106 
107 int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
108 {
109 	struct ptp_clock *ptp = container_of(pccontext->clk, struct ptp_clock, clock);
110 	struct timestamp_event_queue *queue;
111 	char debugfsname[32];
112 
113 	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
114 	if (!queue)
115 		return -EINVAL;
116 	queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
117 	if (!queue->mask) {
118 		kfree(queue);
119 		return -EINVAL;
120 	}
121 	bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
122 	spin_lock_init(&queue->lock);
123 	scoped_guard(spinlock_irq, &ptp->tsevqs_lock)
124 		list_add_tail(&queue->qlist, &ptp->tsevqs);
125 	pccontext->private_clkdata = queue;
126 
127 	/* Debugfs contents */
128 	sprintf(debugfsname, "0x%p", queue);
129 	queue->debugfs_instance =
130 		debugfs_create_dir(debugfsname, ptp->debugfs_root);
131 	queue->dfs_bitmap.array = (u32 *)queue->mask;
132 	queue->dfs_bitmap.n_elements =
133 		DIV_ROUND_UP(PTP_MAX_CHANNELS, BITS_PER_BYTE * sizeof(u32));
134 	debugfs_create_u32_array("mask", 0444, queue->debugfs_instance,
135 				 &queue->dfs_bitmap);
136 
137 	return 0;
138 }
139 
140 int ptp_release(struct posix_clock_context *pccontext)
141 {
142 	struct timestamp_event_queue *queue = pccontext->private_clkdata;
143 	struct ptp_clock *ptp =
144 		container_of(pccontext->clk, struct ptp_clock, clock);
145 
146 	debugfs_remove(queue->debugfs_instance);
147 	pccontext->private_clkdata = NULL;
148 	scoped_guard(spinlock_irq, &ptp->tsevqs_lock)
149 		list_del(&queue->qlist);
150 	bitmap_free(queue->mask);
151 	kfree(queue);
152 	return 0;
153 }
154 
155 static long ptp_clock_getcaps(struct ptp_clock *ptp, void __user *arg)
156 {
157 	struct ptp_clock_caps caps = {
158 		.max_adj		= ptp->info->max_adj,
159 		.n_alarm		= ptp->info->n_alarm,
160 		.n_ext_ts		= ptp->info->n_ext_ts,
161 		.n_per_out		= ptp->info->n_per_out,
162 		.pps			= ptp->info->pps,
163 		.n_pins			= ptp->info->n_pins,
164 		.cross_timestamping	= ptp->info->getcrosststamp != NULL,
165 		.adjust_phase		= ptp->info->adjphase != NULL &&
166 					  ptp->info->getmaxphase != NULL,
167 	};
168 
169 	if (caps.adjust_phase)
170 		caps.max_phase_adj = ptp->info->getmaxphase(ptp->info);
171 
172 	return copy_to_user(arg, &caps, sizeof(caps)) ? -EFAULT : 0;
173 }
174 
175 static long ptp_extts_request(struct ptp_clock *ptp, unsigned int cmd, void __user *arg)
176 {
177 	struct ptp_clock_request req = { .type = PTP_CLK_REQ_EXTTS };
178 	struct ptp_clock_info *ops = ptp->info;
179 	unsigned int supported_extts_flags;
180 
181 	if (copy_from_user(&req.extts, arg, sizeof(req.extts)))
182 		return -EFAULT;
183 
184 	if (cmd == PTP_EXTTS_REQUEST2) {
185 		/* Tell the drivers to check the flags carefully. */
186 		req.extts.flags |= PTP_STRICT_FLAGS;
187 		/* Make sure no reserved bit is set. */
188 		if ((req.extts.flags & ~PTP_EXTTS_VALID_FLAGS) ||
189 		    req.extts.rsv[0] || req.extts.rsv[1])
190 			return -EINVAL;
191 
192 		/* Ensure one of the rising/falling edge bits is set. */
193 		if ((req.extts.flags & PTP_ENABLE_FEATURE) &&
194 		    (req.extts.flags & PTP_EXTTS_EDGES) == 0)
195 			return -EINVAL;
196 	} else {
197 		req.extts.flags &= PTP_EXTTS_V1_VALID_FLAGS;
198 		memset(req.extts.rsv, 0, sizeof(req.extts.rsv));
199 	}
200 
201 	if (req.extts.index >= ops->n_ext_ts)
202 		return -EINVAL;
203 
204 	supported_extts_flags = ptp->info->supported_extts_flags;
205 	/* The PTP_ENABLE_FEATURE flag is always supported. */
206 	supported_extts_flags |= PTP_ENABLE_FEATURE;
207 	/* If the driver does not support strictly checking flags, the
208 	 * PTP_RISING_EDGE and PTP_FALLING_EDGE flags are merely hints
209 	 * which are not enforced.
210 	 */
211 	if (!(supported_extts_flags & PTP_STRICT_FLAGS))
212 		supported_extts_flags |= PTP_EXTTS_EDGES;
213 	/* Reject unsupported flags */
214 	if (req.extts.flags & ~supported_extts_flags)
215 		return -EOPNOTSUPP;
216 
217 	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &ptp->pincfg_mux)
218 		return ops->enable(ops, &req, req.extts.flags & PTP_ENABLE_FEATURE ? 1 : 0);
219 }
220 
221 static long ptp_perout_request(struct ptp_clock *ptp, unsigned int cmd, void __user *arg)
222 {
223 	struct ptp_clock_request req = { .type = PTP_CLK_REQ_PEROUT };
224 	struct ptp_perout_request *perout = &req.perout;
225 	struct ptp_clock_info *ops = ptp->info;
226 
227 	if (copy_from_user(perout, arg, sizeof(*perout)))
228 		return -EFAULT;
229 
230 	if (cmd == PTP_PEROUT_REQUEST2) {
231 		if (perout->flags & ~PTP_PEROUT_VALID_FLAGS)
232 			return -EINVAL;
233 
234 		/*
235 		 * The "on" field has undefined meaning if
236 		 * PTP_PEROUT_DUTY_CYCLE isn't set, we must still treat it
237 		 * as reserved, which must be set to zero.
238 		 */
239 		if (!(perout->flags & PTP_PEROUT_DUTY_CYCLE) &&
240 		    !mem_is_zero(perout->rsv, sizeof(perout->rsv)))
241 			return -EINVAL;
242 
243 		if (perout->flags & PTP_PEROUT_DUTY_CYCLE) {
244 			/* The duty cycle must be subunitary. */
245 			if (perout->on.sec > perout->period.sec ||
246 			    (perout->on.sec == perout->period.sec &&
247 			     perout->on.nsec > perout->period.nsec))
248 				return -ERANGE;
249 		}
250 
251 		if (perout->flags & PTP_PEROUT_PHASE) {
252 			/*
253 			 * The phase should be specified modulo the period,
254 			 * therefore anything equal or larger than 1 period
255 			 * is invalid.
256 			 */
257 			if (perout->phase.sec > perout->period.sec ||
258 			    (perout->phase.sec == perout->period.sec &&
259 			     perout->phase.nsec >= perout->period.nsec))
260 				return -ERANGE;
261 		}
262 	} else {
263 		perout->flags &= PTP_PEROUT_V1_VALID_FLAGS;
264 		memset(perout->rsv, 0, sizeof(perout->rsv));
265 	}
266 
267 	if (perout->index >= ops->n_per_out)
268 		return -EINVAL;
269 	if (perout->flags & ~ops->supported_perout_flags)
270 		return -EOPNOTSUPP;
271 
272 	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &ptp->pincfg_mux)
273 		return ops->enable(ops, &req, perout->period.sec || perout->period.nsec);
274 }
275 
276 static long ptp_enable_pps(struct ptp_clock *ptp, bool enable)
277 {
278 	struct ptp_clock_request req = { .type = PTP_CLK_REQ_PPS };
279 	struct ptp_clock_info *ops = ptp->info;
280 
281 	if (!capable(CAP_SYS_TIME))
282 		return -EPERM;
283 
284 	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &ptp->pincfg_mux)
285 		return ops->enable(ops, &req, enable);
286 }
287 
288 static long ptp_sys_offset_precise(struct ptp_clock *ptp, void __user *arg)
289 {
290 	struct ptp_sys_offset_precise precise_offset;
291 	struct system_device_crosststamp xtstamp;
292 	struct timespec64 ts;
293 	int err;
294 
295 	if (!ptp->info->getcrosststamp)
296 		return -EOPNOTSUPP;
297 
298 	err = ptp->info->getcrosststamp(ptp->info, &xtstamp);
299 	if (err)
300 		return err;
301 
302 	memset(&precise_offset, 0, sizeof(precise_offset));
303 	ts = ktime_to_timespec64(xtstamp.device);
304 	precise_offset.device.sec = ts.tv_sec;
305 	precise_offset.device.nsec = ts.tv_nsec;
306 	ts = ktime_to_timespec64(xtstamp.sys_realtime);
307 	precise_offset.sys_realtime.sec = ts.tv_sec;
308 	precise_offset.sys_realtime.nsec = ts.tv_nsec;
309 	ts = ktime_to_timespec64(xtstamp.sys_monoraw);
310 	precise_offset.sys_monoraw.sec = ts.tv_sec;
311 	precise_offset.sys_monoraw.nsec = ts.tv_nsec;
312 
313 	return copy_to_user(arg, &precise_offset, sizeof(precise_offset)) ? -EFAULT : 0;
314 }
315 
316 static long ptp_sys_offset_extended(struct ptp_clock *ptp, void __user *arg)
317 {
318 	struct ptp_sys_offset_extended *extoff __free(kfree) = NULL;
319 	struct ptp_system_timestamp sts;
320 
321 	if (!ptp->info->gettimex64)
322 		return -EOPNOTSUPP;
323 
324 	extoff = memdup_user(arg, sizeof(*extoff));
325 	if (IS_ERR(extoff))
326 		return PTR_ERR(extoff);
327 
328 	if (extoff->n_samples > PTP_MAX_SAMPLES || extoff->rsv[0] || extoff->rsv[1])
329 		return -EINVAL;
330 
331 	switch (extoff->clockid) {
332 	case CLOCK_REALTIME:
333 	case CLOCK_MONOTONIC:
334 	case CLOCK_MONOTONIC_RAW:
335 		break;
336 	case CLOCK_AUX ... CLOCK_AUX_LAST:
337 		if (IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS))
338 			break;
339 		fallthrough;
340 	default:
341 		return -EINVAL;
342 	}
343 
344 	sts.clockid = extoff->clockid;
345 	for (unsigned int i = 0; i < extoff->n_samples; i++) {
346 		struct timespec64 ts;
347 		int err;
348 
349 		err = ptp->info->gettimex64(ptp->info, &ts, &sts);
350 		if (err)
351 			return err;
352 
353 		/* Filter out disabled or unavailable clocks */
354 		if (sts.pre_ts.tv_sec < 0 || sts.post_ts.tv_sec < 0)
355 			return -EINVAL;
356 
357 		extoff->ts[i][0].sec = sts.pre_ts.tv_sec;
358 		extoff->ts[i][0].nsec = sts.pre_ts.tv_nsec;
359 		extoff->ts[i][1].sec = ts.tv_sec;
360 		extoff->ts[i][1].nsec = ts.tv_nsec;
361 		extoff->ts[i][2].sec = sts.post_ts.tv_sec;
362 		extoff->ts[i][2].nsec = sts.post_ts.tv_nsec;
363 	}
364 
365 	return copy_to_user(arg, extoff, sizeof(*extoff)) ? -EFAULT : 0;
366 }
367 
368 static long ptp_sys_offset(struct ptp_clock *ptp, void __user *arg)
369 {
370 	struct ptp_sys_offset *sysoff __free(kfree) = NULL;
371 	struct ptp_clock_time *pct;
372 	struct timespec64 ts;
373 
374 	sysoff = memdup_user(arg, sizeof(*sysoff));
375 	if (IS_ERR(sysoff))
376 		return PTR_ERR(sysoff);
377 
378 	if (sysoff->n_samples > PTP_MAX_SAMPLES)
379 		return -EINVAL;
380 
381 	pct = &sysoff->ts[0];
382 	for (unsigned int i = 0; i < sysoff->n_samples; i++) {
383 		struct ptp_clock_info *ops = ptp->info;
384 		int err;
385 
386 		ktime_get_real_ts64(&ts);
387 		pct->sec = ts.tv_sec;
388 		pct->nsec = ts.tv_nsec;
389 		pct++;
390 		if (ops->gettimex64)
391 			err = ops->gettimex64(ops, &ts, NULL);
392 		else
393 			err = ops->gettime64(ops, &ts);
394 		if (err)
395 			return err;
396 		pct->sec = ts.tv_sec;
397 		pct->nsec = ts.tv_nsec;
398 		pct++;
399 	}
400 	ktime_get_real_ts64(&ts);
401 	pct->sec = ts.tv_sec;
402 	pct->nsec = ts.tv_nsec;
403 
404 	return copy_to_user(arg, sysoff, sizeof(*sysoff)) ? -EFAULT : 0;
405 }
406 
407 static long ptp_pin_getfunc(struct ptp_clock *ptp, unsigned int cmd, void __user *arg)
408 {
409 	struct ptp_clock_info *ops = ptp->info;
410 	struct ptp_pin_desc pd;
411 
412 	if (copy_from_user(&pd, arg, sizeof(pd)))
413 		return -EFAULT;
414 
415 	if (cmd == PTP_PIN_GETFUNC2 && !mem_is_zero(pd.rsv, sizeof(pd.rsv)))
416 		return -EINVAL;
417 
418 	if (pd.index >= ops->n_pins)
419 		return -EINVAL;
420 
421 	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &ptp->pincfg_mux)
422 		pd = ops->pin_config[array_index_nospec(pd.index, ops->n_pins)];
423 
424 	return copy_to_user(arg, &pd, sizeof(pd)) ? -EFAULT : 0;
425 }
426 
427 static long ptp_pin_setfunc(struct ptp_clock *ptp, unsigned int cmd, void __user *arg)
428 {
429 	struct ptp_clock_info *ops = ptp->info;
430 	struct ptp_pin_desc pd;
431 	unsigned int pin_index;
432 
433 	if (copy_from_user(&pd, arg, sizeof(pd)))
434 		return -EFAULT;
435 
436 	if (cmd == PTP_PIN_SETFUNC2 && !mem_is_zero(pd.rsv, sizeof(pd.rsv)))
437 		return -EINVAL;
438 
439 	if (pd.index >= ops->n_pins)
440 		return -EINVAL;
441 
442 	pin_index = array_index_nospec(pd.index, ops->n_pins);
443 	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &ptp->pincfg_mux)
444 		return ptp_set_pinfunc(ptp, pin_index, pd.func, pd.chan);
445 }
446 
447 static long ptp_mask_clear_all(struct timestamp_event_queue *tsevq)
448 {
449 	bitmap_clear(tsevq->mask, 0, PTP_MAX_CHANNELS);
450 	return 0;
451 }
452 
453 static long ptp_mask_en_single(struct timestamp_event_queue *tsevq, void __user *arg)
454 {
455 	unsigned int channel;
456 
457 	if (copy_from_user(&channel, arg, sizeof(channel)))
458 		return -EFAULT;
459 	if (channel >= PTP_MAX_CHANNELS)
460 		return -EFAULT;
461 	set_bit(channel, tsevq->mask);
462 	return 0;
463 }
464 
465 long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd,
466 	       unsigned long arg)
467 {
468 	struct ptp_clock *ptp = container_of(pccontext->clk, struct ptp_clock, clock);
469 	void __user *argptr;
470 
471 	if (in_compat_syscall() && cmd != PTP_ENABLE_PPS && cmd != PTP_ENABLE_PPS2)
472 		arg = (unsigned long)compat_ptr(arg);
473 	argptr = (void __force __user *)arg;
474 
475 	switch (cmd) {
476 	case PTP_CLOCK_GETCAPS:
477 	case PTP_CLOCK_GETCAPS2:
478 		return ptp_clock_getcaps(ptp, argptr);
479 
480 	case PTP_EXTTS_REQUEST:
481 	case PTP_EXTTS_REQUEST2:
482 		if ((pccontext->fp->f_mode & FMODE_WRITE) == 0)
483 			return -EACCES;
484 		return ptp_extts_request(ptp, cmd, argptr);
485 
486 	case PTP_PEROUT_REQUEST:
487 	case PTP_PEROUT_REQUEST2:
488 		if ((pccontext->fp->f_mode & FMODE_WRITE) == 0)
489 			return -EACCES;
490 		return ptp_perout_request(ptp, cmd, argptr);
491 
492 	case PTP_ENABLE_PPS:
493 	case PTP_ENABLE_PPS2:
494 		if ((pccontext->fp->f_mode & FMODE_WRITE) == 0)
495 			return -EACCES;
496 		return ptp_enable_pps(ptp, !!arg);
497 
498 	case PTP_SYS_OFFSET_PRECISE:
499 	case PTP_SYS_OFFSET_PRECISE2:
500 		return ptp_sys_offset_precise(ptp, argptr);
501 
502 	case PTP_SYS_OFFSET_EXTENDED:
503 	case PTP_SYS_OFFSET_EXTENDED2:
504 		return ptp_sys_offset_extended(ptp, argptr);
505 
506 	case PTP_SYS_OFFSET:
507 	case PTP_SYS_OFFSET2:
508 		return ptp_sys_offset(ptp, argptr);
509 
510 	case PTP_PIN_GETFUNC:
511 	case PTP_PIN_GETFUNC2:
512 		return ptp_pin_getfunc(ptp, cmd, argptr);
513 
514 	case PTP_PIN_SETFUNC:
515 	case PTP_PIN_SETFUNC2:
516 		if ((pccontext->fp->f_mode & FMODE_WRITE) == 0)
517 			return -EACCES;
518 		return ptp_pin_setfunc(ptp, cmd, argptr);
519 
520 	case PTP_MASK_CLEAR_ALL:
521 		return ptp_mask_clear_all(pccontext->private_clkdata);
522 
523 	case PTP_MASK_EN_SINGLE:
524 		return ptp_mask_en_single(pccontext->private_clkdata, argptr);
525 
526 	default:
527 		return -ENOTTY;
528 	}
529 }
530 
531 __poll_t ptp_poll(struct posix_clock_context *pccontext, struct file *fp,
532 		  poll_table *wait)
533 {
534 	struct ptp_clock *ptp =
535 		container_of(pccontext->clk, struct ptp_clock, clock);
536 	struct timestamp_event_queue *queue;
537 
538 	queue = pccontext->private_clkdata;
539 	if (!queue)
540 		return EPOLLERR;
541 
542 	poll_wait(fp, &ptp->tsev_wq, wait);
543 
544 	return queue_cnt(queue) ? EPOLLIN : 0;
545 }
546 
547 #define EXTTS_BUFSIZE (PTP_BUF_TIMESTAMPS * sizeof(struct ptp_extts_event))
548 
549 ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
550 		 char __user *buf, size_t cnt)
551 {
552 	struct ptp_clock *ptp =	container_of(pccontext->clk, struct ptp_clock, clock);
553 	struct timestamp_event_queue *queue;
554 	struct ptp_extts_event *event;
555 	ssize_t result;
556 
557 	queue = pccontext->private_clkdata;
558 	if (!queue)
559 		return -EINVAL;
560 
561 	if (cnt % sizeof(*event) != 0)
562 		return -EINVAL;
563 
564 	if (cnt > EXTTS_BUFSIZE)
565 		cnt = EXTTS_BUFSIZE;
566 
567 	if (wait_event_interruptible(ptp->tsev_wq, ptp->defunct || queue_cnt(queue)))
568 		return -ERESTARTSYS;
569 
570 	if (ptp->defunct)
571 		return -ENODEV;
572 
573 	event = kmalloc(EXTTS_BUFSIZE, GFP_KERNEL);
574 	if (!event)
575 		return -ENOMEM;
576 
577 	scoped_guard(spinlock_irq, &queue->lock) {
578 		size_t qcnt = min((size_t)queue_cnt(queue), cnt / sizeof(*event));
579 
580 		for (size_t i = 0; i < qcnt; i++) {
581 			event[i] = queue->buf[queue->head];
582 			/* Paired with READ_ONCE() in queue_cnt() */
583 			WRITE_ONCE(queue->head, (queue->head + 1) % PTP_MAX_TIMESTAMPS);
584 		}
585 		cnt = qcnt * sizeof(*event);
586 	}
587 
588 	result = cnt;
589 	if (copy_to_user(buf, event, cnt))
590 		result = -EFAULT;
591 
592 	kfree(event);
593 	return result;
594 }
595