1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2014 Dmitry Chagin <dchagin@FreeBSD.org>
5 * Copyright (c) 2023 Jake Freeland <jfree@FreeBSD.org>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/callout.h>
32 #include <sys/fcntl.h>
33 #include <sys/file.h>
34 #include <sys/filedesc.h>
35 #include <sys/filio.h>
36 #include <sys/kernel.h>
37 #include <sys/lock.h>
38 #include <sys/malloc.h>
39 #include <sys/mount.h>
40 #include <sys/mutex.h>
41 #include <sys/poll.h>
42 #include <sys/proc.h>
43 #include <sys/queue.h>
44 #include <sys/selinfo.h>
45 #include <sys/stat.h>
46 #include <sys/sx.h>
47 #include <sys/syscallsubr.h>
48 #include <sys/sysctl.h>
49 #include <sys/sysent.h>
50 #include <sys/sysproto.h>
51 #include <sys/timerfd.h>
52 #include <sys/timespec.h>
53 #include <sys/uio.h>
54 #include <sys/user.h>
55
56 #include <security/audit/audit.h>
57
58 static MALLOC_DEFINE(M_TIMERFD, "timerfd", "timerfd structures");
59
60 static struct mtx timerfd_list_lock;
61 static LIST_HEAD(, timerfd) timerfd_list;
62 MTX_SYSINIT(timerfd, &timerfd_list_lock, "timerfd_list_lock", MTX_DEF);
63
64 static struct unrhdr64 tfdino_unr;
65
66 #define TFD_NOJUMP 0 /* Realtime clock has not jumped. */
67 #define TFD_READ 1 /* Jumped, tfd has been read since. */
68 #define TFD_ZREAD 2 /* Jumped backwards, CANCEL_ON_SET=false. */
69 #define TFD_CANCELED 4 /* Jumped, CANCEL_ON_SET=true. */
70 #define TFD_JUMPED (TFD_ZREAD | TFD_CANCELED)
71
72 /*
73 * One structure allocated per timerfd descriptor.
74 *
75 * Locking semantics:
76 * (t) locked by tfd_lock mtx
77 * (l) locked by timerfd_list_lock sx
78 * (c) const until freeing
79 */
80 struct timerfd {
81 /* User specified. */
82 struct itimerspec tfd_time; /* (t) tfd timer */
83 clockid_t tfd_clockid; /* (c) timing base */
84 int tfd_flags; /* (c) creation flags */
85 int tfd_timflags; /* (t) timer flags */
86
87 /* Used internally. */
88 timerfd_t tfd_count; /* (t) expiration count since read */
89 bool tfd_expired; /* (t) true upon initial expiration */
90 struct mtx tfd_lock; /* tfd mtx lock */
91 struct callout tfd_callout; /* (t) expiration notification */
92 struct selinfo tfd_sel; /* (t) I/O alerts */
93 struct timespec tfd_boottim; /* (t) cached boottime */
94 int tfd_jumped; /* (t) timer jump status */
95 LIST_ENTRY(timerfd) entry; /* (l) entry in list */
96
97 /* For stat(2). */
98 ino_t tfd_ino; /* (c) inode number */
99 struct timespec tfd_atim; /* (t) time of last read */
100 struct timespec tfd_mtim; /* (t) time of last settime */
101 struct timespec tfd_birthtim; /* (c) creation time */
102 };
103
104 static void
timerfd_init(void * data)105 timerfd_init(void *data)
106 {
107 new_unrhdr64(&tfdino_unr, 1);
108 }
109
110 SYSINIT(timerfd, SI_SUB_VFS, SI_ORDER_ANY, timerfd_init, NULL);
111
112 static inline void
timerfd_getboottime(struct timespec * ts)113 timerfd_getboottime(struct timespec *ts)
114 {
115 struct timeval tv;
116
117 getboottime(&tv);
118 TIMEVAL_TO_TIMESPEC(&tv, ts);
119 }
120
121 /*
122 * Call when a discontinuous jump has occured in CLOCK_REALTIME and
123 * update timerfd's cached boottime. A jump can be triggered using
124 * functions like clock_settime(2) or settimeofday(2).
125 *
126 * Timer is marked TFD_CANCELED if TFD_TIMER_CANCEL_ON_SET is set
127 * and the realtime clock jumps.
128 * Timer is marked TFD_ZREAD if TFD_TIMER_CANCEL_ON_SET is not set,
129 * but the realtime clock jumps backwards.
130 */
131 void
timerfd_jumped(void)132 timerfd_jumped(void)
133 {
134 struct timerfd *tfd;
135 struct timespec boottime, diff;
136
137 if (LIST_EMPTY(&timerfd_list))
138 return;
139
140 timerfd_getboottime(&boottime);
141 mtx_lock(&timerfd_list_lock);
142 LIST_FOREACH(tfd, &timerfd_list, entry) {
143 mtx_lock(&tfd->tfd_lock);
144 if (tfd->tfd_clockid != CLOCK_REALTIME ||
145 (tfd->tfd_timflags & TFD_TIMER_ABSTIME) == 0 ||
146 timespeccmp(&boottime, &tfd->tfd_boottim, ==)) {
147 mtx_unlock(&tfd->tfd_lock);
148 continue;
149 }
150
151 if (callout_active(&tfd->tfd_callout)) {
152 if ((tfd->tfd_timflags & TFD_TIMER_CANCEL_ON_SET) != 0)
153 tfd->tfd_jumped = TFD_CANCELED;
154 else if (timespeccmp(&boottime, &tfd->tfd_boottim, <))
155 tfd->tfd_jumped = TFD_ZREAD;
156
157 /*
158 * Do not reschedule callout when
159 * inside interval time loop.
160 */
161 if (!tfd->tfd_expired) {
162 timespecsub(&boottime,
163 &tfd->tfd_boottim, &diff);
164 timespecsub(&tfd->tfd_time.it_value,
165 &diff, &tfd->tfd_time.it_value);
166 if (callout_stop(&tfd->tfd_callout) == 1) {
167 callout_schedule_sbt(&tfd->tfd_callout,
168 tstosbt(tfd->tfd_time.it_value),
169 0, C_ABSOLUTE);
170 }
171 }
172 }
173
174 tfd->tfd_boottim = boottime;
175 mtx_unlock(&tfd->tfd_lock);
176 }
177 mtx_unlock(&timerfd_list_lock);
178 }
179
180 static int
timerfd_read(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)181 timerfd_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
182 int flags, struct thread *td)
183 {
184 struct timerfd *tfd = fp->f_data;
185 timerfd_t count;
186 int error = 0;
187
188 if (uio->uio_resid < sizeof(timerfd_t))
189 return (EINVAL);
190
191 mtx_lock(&tfd->tfd_lock);
192 retry:
193 getnanotime(&tfd->tfd_atim);
194 if ((tfd->tfd_jumped & TFD_JUMPED) != 0) {
195 if (tfd->tfd_jumped == TFD_CANCELED)
196 error = ECANCELED;
197 tfd->tfd_jumped = TFD_READ;
198 tfd->tfd_count = 0;
199 mtx_unlock(&tfd->tfd_lock);
200 return (error);
201 } else {
202 tfd->tfd_jumped = TFD_NOJUMP;
203 }
204 if (tfd->tfd_count == 0) {
205 if ((fp->f_flag & FNONBLOCK) != 0) {
206 mtx_unlock(&tfd->tfd_lock);
207 return (EAGAIN);
208 }
209 error = mtx_sleep(&tfd->tfd_count, &tfd->tfd_lock,
210 PCATCH, "tfdrd", 0);
211 if (error == 0) {
212 goto retry;
213 } else {
214 mtx_unlock(&tfd->tfd_lock);
215 return (error);
216 }
217 }
218
219 count = tfd->tfd_count;
220 tfd->tfd_count = 0;
221 mtx_unlock(&tfd->tfd_lock);
222 error = uiomove(&count, sizeof(timerfd_t), uio);
223
224 return (error);
225 }
226
227 static int
timerfd_ioctl(struct file * fp,u_long cmd,void * data,struct ucred * active_cred,struct thread * td)228 timerfd_ioctl(struct file *fp, u_long cmd, void *data,
229 struct ucred *active_cred, struct thread *td)
230 {
231 switch (cmd) {
232 case FIOASYNC:
233 if (*(int *)data != 0)
234 atomic_set_int(&fp->f_flag, FASYNC);
235 else
236 atomic_clear_int(&fp->f_flag, FASYNC);
237 return (0);
238 case FIONBIO:
239 if (*(int *)data != 0)
240 atomic_set_int(&fp->f_flag, FNONBLOCK);
241 else
242 atomic_clear_int(&fp->f_flag, FNONBLOCK);
243 return (0);
244 }
245 return (ENOTTY);
246 }
247
248 static int
timerfd_poll(struct file * fp,int events,struct ucred * active_cred,struct thread * td)249 timerfd_poll(struct file *fp, int events, struct ucred *active_cred,
250 struct thread *td)
251 {
252 struct timerfd *tfd = fp->f_data;
253 int revents = 0;
254
255 mtx_lock(&tfd->tfd_lock);
256 if ((events & (POLLIN | POLLRDNORM)) != 0 &&
257 tfd->tfd_count > 0 && tfd->tfd_jumped != TFD_READ)
258 revents |= events & (POLLIN | POLLRDNORM);
259 if (revents == 0)
260 selrecord(td, &tfd->tfd_sel);
261 mtx_unlock(&tfd->tfd_lock);
262
263 return (revents);
264 }
265
266 static void
filt_timerfddetach(struct knote * kn)267 filt_timerfddetach(struct knote *kn)
268 {
269 struct timerfd *tfd = kn->kn_hook;
270
271 mtx_lock(&tfd->tfd_lock);
272 knlist_remove(&tfd->tfd_sel.si_note, kn, 1);
273 mtx_unlock(&tfd->tfd_lock);
274 }
275
276 static int
filt_timerfdread(struct knote * kn,long hint)277 filt_timerfdread(struct knote *kn, long hint)
278 {
279 struct timerfd *tfd = kn->kn_hook;
280
281 mtx_assert(&tfd->tfd_lock, MA_OWNED);
282 kn->kn_data = (int64_t)tfd->tfd_count;
283 return (tfd->tfd_count > 0);
284 }
285
286 static const struct filterops timerfd_rfiltops = {
287 .f_isfd = 1,
288 .f_detach = filt_timerfddetach,
289 .f_event = filt_timerfdread,
290 };
291
292 static int
timerfd_kqfilter(struct file * fp,struct knote * kn)293 timerfd_kqfilter(struct file *fp, struct knote *kn)
294 {
295 struct timerfd *tfd = fp->f_data;
296
297 if (kn->kn_filter != EVFILT_READ)
298 return (EINVAL);
299
300 kn->kn_fop = &timerfd_rfiltops;
301 kn->kn_hook = tfd;
302 knlist_add(&tfd->tfd_sel.si_note, kn, 0);
303
304 return (0);
305 }
306
307 static int
timerfd_stat(struct file * fp,struct stat * sb,struct ucred * active_cred)308 timerfd_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
309 {
310 struct timerfd *tfd = fp->f_data;
311
312 bzero(sb, sizeof(*sb));
313 sb->st_nlink = fp->f_count - 1;
314 sb->st_uid = fp->f_cred->cr_uid;
315 sb->st_gid = fp->f_cred->cr_gid;
316 sb->st_blksize = PAGE_SIZE;
317 mtx_lock(&tfd->tfd_lock);
318 sb->st_atim = tfd->tfd_atim;
319 sb->st_mtim = tfd->tfd_mtim;
320 mtx_unlock(&tfd->tfd_lock);
321 sb->st_ctim = sb->st_mtim;
322 sb->st_ino = tfd->tfd_ino;
323 sb->st_birthtim = tfd->tfd_birthtim;
324
325 return (0);
326 }
327
328 static int
timerfd_close(struct file * fp,struct thread * td)329 timerfd_close(struct file *fp, struct thread *td)
330 {
331 struct timerfd *tfd = fp->f_data;
332
333 mtx_lock(&timerfd_list_lock);
334 LIST_REMOVE(tfd, entry);
335 mtx_unlock(&timerfd_list_lock);
336
337 callout_drain(&tfd->tfd_callout);
338 seldrain(&tfd->tfd_sel);
339 knlist_destroy(&tfd->tfd_sel.si_note);
340 mtx_destroy(&tfd->tfd_lock);
341 free(tfd, M_TIMERFD);
342 fp->f_ops = &badfileops;
343
344 return (0);
345 }
346
347 static int
timerfd_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp)348 timerfd_fill_kinfo(struct file *fp, struct kinfo_file *kif,
349 struct filedesc *fdp)
350 {
351 struct timerfd *tfd = fp->f_data;
352
353 kif->kf_type = KF_TYPE_TIMERFD;
354 kif->kf_un.kf_timerfd.kf_timerfd_clockid = tfd->tfd_clockid;
355 kif->kf_un.kf_timerfd.kf_timerfd_flags = tfd->tfd_flags;
356 kif->kf_un.kf_timerfd.kf_timerfd_addr = (uintptr_t)tfd;
357
358 return (0);
359 }
360
361 static const struct fileops timerfdops = {
362 .fo_read = timerfd_read,
363 .fo_write = invfo_rdwr,
364 .fo_truncate = invfo_truncate,
365 .fo_ioctl = timerfd_ioctl,
366 .fo_poll = timerfd_poll,
367 .fo_kqfilter = timerfd_kqfilter,
368 .fo_stat = timerfd_stat,
369 .fo_close = timerfd_close,
370 .fo_chmod = invfo_chmod,
371 .fo_chown = invfo_chown,
372 .fo_sendfile = invfo_sendfile,
373 .fo_fill_kinfo = timerfd_fill_kinfo,
374 .fo_cmp = file_kcmp_generic,
375 .fo_flags = DFLAG_PASSABLE,
376 };
377
378 static void
timerfd_curval(struct timerfd * tfd,struct itimerspec * old_value)379 timerfd_curval(struct timerfd *tfd, struct itimerspec *old_value)
380 {
381 struct timespec curr_value;
382
383 mtx_assert(&tfd->tfd_lock, MA_OWNED);
384 *old_value = tfd->tfd_time;
385 if (timespecisset(&tfd->tfd_time.it_value)) {
386 nanouptime(&curr_value);
387 timespecsub(&tfd->tfd_time.it_value, &curr_value,
388 &old_value->it_value);
389 }
390 }
391
392 static void
timerfd_expire(void * arg)393 timerfd_expire(void *arg)
394 {
395 struct timerfd *tfd = (struct timerfd *)arg;
396 struct timespec uptime;
397
398 ++tfd->tfd_count;
399 tfd->tfd_expired = true;
400 if (timespecisset(&tfd->tfd_time.it_interval)) {
401 /* Count missed events. */
402 nanouptime(&uptime);
403 if (timespeccmp(&uptime, &tfd->tfd_time.it_value, >)) {
404 timespecsub(&uptime, &tfd->tfd_time.it_value, &uptime);
405 tfd->tfd_count += tstosbt(uptime) /
406 tstosbt(tfd->tfd_time.it_interval);
407 }
408 timespecadd(&tfd->tfd_time.it_value,
409 &tfd->tfd_time.it_interval, &tfd->tfd_time.it_value);
410 callout_schedule_sbt(&tfd->tfd_callout,
411 tstosbt(tfd->tfd_time.it_value),
412 0, C_ABSOLUTE);
413 } else {
414 /* Single shot timer. */
415 callout_deactivate(&tfd->tfd_callout);
416 timespecclear(&tfd->tfd_time.it_value);
417 }
418
419 wakeup(&tfd->tfd_count);
420 selwakeup(&tfd->tfd_sel);
421 KNOTE_LOCKED(&tfd->tfd_sel.si_note, 0);
422 }
423
424 int
kern_timerfd_create(struct thread * td,int clockid,int flags)425 kern_timerfd_create(struct thread *td, int clockid, int flags)
426 {
427 struct file *fp;
428 struct timerfd *tfd;
429 int error, fd, fflags;
430
431 AUDIT_ARG_VALUE(clockid);
432 AUDIT_ARG_FFLAGS(flags);
433
434 switch (clockid) {
435 case CLOCK_REALTIME:
436 /* FALLTHROUGH */
437 case CLOCK_MONOTONIC:
438 /* FALLTHROUGH */
439 case CLOCK_UPTIME:
440 /*
441 * CLOCK_BOOTTIME should be added once different from
442 * CLOCK_UPTIME
443 */
444 break;
445 default:
446 return (EINVAL);
447 }
448 if ((flags & ~(TFD_CLOEXEC | TFD_NONBLOCK)) != 0)
449 return (EINVAL);
450
451 fflags = FREAD;
452 if ((flags & TFD_CLOEXEC) != 0)
453 fflags |= O_CLOEXEC;
454 if ((flags & TFD_NONBLOCK) != 0)
455 fflags |= FNONBLOCK;
456
457 error = falloc(td, &fp, &fd, fflags);
458 if (error != 0)
459 return (error);
460
461 tfd = malloc(sizeof(*tfd), M_TIMERFD, M_WAITOK | M_ZERO);
462 tfd->tfd_clockid = (clockid_t)clockid;
463 tfd->tfd_flags = flags;
464 tfd->tfd_ino = alloc_unr64(&tfdino_unr);
465 mtx_init(&tfd->tfd_lock, "timerfd", NULL, MTX_DEF);
466 callout_init_mtx(&tfd->tfd_callout, &tfd->tfd_lock, 0);
467 knlist_init_mtx(&tfd->tfd_sel.si_note, &tfd->tfd_lock);
468 timerfd_getboottime(&tfd->tfd_boottim);
469 getnanotime(&tfd->tfd_birthtim);
470 mtx_lock(&timerfd_list_lock);
471 LIST_INSERT_HEAD(&timerfd_list, tfd, entry);
472 mtx_unlock(&timerfd_list_lock);
473
474 finit(fp, fflags, DTYPE_TIMERFD, tfd, &timerfdops);
475
476 fdrop(fp, td);
477
478 td->td_retval[0] = fd;
479 return (0);
480 }
481
482 int
kern_timerfd_gettime(struct thread * td,int fd,struct itimerspec * curr_value)483 kern_timerfd_gettime(struct thread *td, int fd, struct itimerspec *curr_value)
484 {
485 struct file *fp;
486 struct timerfd *tfd;
487 int error;
488
489 error = fget(td, fd, &cap_write_rights, &fp);
490 if (error != 0)
491 return (error);
492 if (fp->f_type != DTYPE_TIMERFD) {
493 fdrop(fp, td);
494 return (EINVAL);
495 }
496 tfd = fp->f_data;
497
498 mtx_lock(&tfd->tfd_lock);
499 timerfd_curval(tfd, curr_value);
500 mtx_unlock(&tfd->tfd_lock);
501
502 fdrop(fp, td);
503 return (0);
504 }
505
506 int
kern_timerfd_settime(struct thread * td,int fd,int flags,const struct itimerspec * new_value,struct itimerspec * old_value)507 kern_timerfd_settime(struct thread *td, int fd, int flags,
508 const struct itimerspec *new_value, struct itimerspec *old_value)
509 {
510 struct file *fp;
511 struct timerfd *tfd;
512 struct timespec ts;
513 int error = 0;
514
515 if ((flags & ~(TFD_TIMER_ABSTIME | TFD_TIMER_CANCEL_ON_SET)) != 0)
516 return (EINVAL);
517 if (!timespecvalid_interval(&new_value->it_value) ||
518 !timespecvalid_interval(&new_value->it_interval))
519 return (EINVAL);
520
521 error = fget(td, fd, &cap_write_rights, &fp);
522 if (error != 0)
523 return (error);
524 if (fp->f_type != DTYPE_TIMERFD) {
525 fdrop(fp, td);
526 return (EINVAL);
527 }
528 tfd = fp->f_data;
529
530 mtx_lock(&tfd->tfd_lock);
531 getnanotime(&tfd->tfd_mtim);
532 tfd->tfd_timflags = flags;
533
534 /* Store old itimerspec, if applicable. */
535 if (old_value != NULL)
536 timerfd_curval(tfd, old_value);
537
538 /* Set new expiration. */
539 tfd->tfd_time = *new_value;
540 if (timespecisset(&tfd->tfd_time.it_value)) {
541 if ((flags & TFD_TIMER_ABSTIME) == 0) {
542 nanouptime(&ts);
543 timespecadd(&tfd->tfd_time.it_value, &ts,
544 &tfd->tfd_time.it_value);
545 } else if (tfd->tfd_clockid == CLOCK_REALTIME) {
546 /* ECANCELED if unread jump is pending. */
547 if (tfd->tfd_jumped == TFD_CANCELED)
548 error = ECANCELED;
549 /* Convert from CLOCK_REALTIME to CLOCK_BOOTTIME. */
550 timespecsub(&tfd->tfd_time.it_value, &tfd->tfd_boottim,
551 &tfd->tfd_time.it_value);
552 }
553 callout_reset_sbt(&tfd->tfd_callout,
554 tstosbt(tfd->tfd_time.it_value),
555 0, timerfd_expire, tfd, C_ABSOLUTE);
556 } else {
557 callout_stop(&tfd->tfd_callout);
558 }
559 tfd->tfd_count = 0;
560 tfd->tfd_expired = false;
561 tfd->tfd_jumped = TFD_NOJUMP;
562 mtx_unlock(&tfd->tfd_lock);
563
564 fdrop(fp, td);
565 return (error);
566 }
567
568 int
sys_timerfd_create(struct thread * td,struct timerfd_create_args * uap)569 sys_timerfd_create(struct thread *td, struct timerfd_create_args *uap)
570 {
571 return (kern_timerfd_create(td, uap->clockid, uap->flags));
572 }
573
574 int
sys_timerfd_gettime(struct thread * td,struct timerfd_gettime_args * uap)575 sys_timerfd_gettime(struct thread *td, struct timerfd_gettime_args *uap)
576 {
577 struct itimerspec curr_value;
578 int error;
579
580 error = kern_timerfd_gettime(td, uap->fd, &curr_value);
581 if (error == 0)
582 error = copyout(&curr_value, uap->curr_value,
583 sizeof(curr_value));
584
585 return (error);
586 }
587
588 int
sys_timerfd_settime(struct thread * td,struct timerfd_settime_args * uap)589 sys_timerfd_settime(struct thread *td, struct timerfd_settime_args *uap)
590 {
591 struct itimerspec new_value, old_value;
592 int error;
593
594 error = copyin(uap->new_value, &new_value, sizeof(new_value));
595 if (error != 0)
596 return (error);
597 if (uap->old_value == NULL) {
598 error = kern_timerfd_settime(td, uap->fd, uap->flags,
599 &new_value, NULL);
600 } else {
601 error = kern_timerfd_settime(td, uap->fd, uap->flags,
602 &new_value, &old_value);
603 if (error == 0)
604 error = copyout(&old_value, uap->old_value,
605 sizeof(old_value));
606 }
607 return (error);
608 }
609