bsd/kern/kern_synch.c

   1 /*
   2  * Copyright (c) 2000-2020 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * Mach Operating System
  30  * Copyright (c) 1987 Carnegie-Mellon University
  31  * All rights reserved.  The CMU software License Agreement specifies
  32  * the terms and conditions for use and redistribution.
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/systm.h>
  37 #include <sys/proc_internal.h>
  38 #include <sys/user.h>
  39 #include <sys/file_internal.h>
  40 #include <sys/vnode.h>
  41 #include <sys/kernel.h>
  42
  43 #include <kern/queue.h>
  44 #include <sys/lock.h>
  45 #include <kern/thread.h>
  46 #include <kern/sched_prim.h>
  47 #include <kern/ast.h>
  48
  49 #include <kern/cpu_number.h>
  50 #include <vm/vm_kern.h>
  51
  52 #include <kern/task.h>
  53 #include <mach/time_value.h>
  54 #include <kern/locks.h>
  55 #include <kern/policy_internal.h>
  56
  57 #include <sys/systm.h>                  /* for unix_syscall_return() */
  58 #include <libkern/OSAtomic.h>
  59
  60 extern void compute_averunnable(void *);        /* XXX */
  61
  62 __attribute__((noreturn))
  63 static void
  64 _sleep_continue( __unused void *parameter, wait_result_t wresult)
  65 {
  66         struct proc *p = current_proc();
  67         thread_t self  = current_thread();
  68         struct uthread * ut;
  69         int sig, catch;
  70         int error = 0;
  71         int dropmutex, spinmutex;
  72
  73         ut = get_bsdthread_info(self);
  74         catch     = ut->uu_pri & PCATCH;
  75         dropmutex = ut->uu_pri & PDROP;
  76         spinmutex = ut->uu_pri & PSPIN;
  77
  78         switch (wresult) {
  79         case THREAD_TIMED_OUT:
  80                 error = EWOULDBLOCK;
  81                 break;
  82         case THREAD_AWAKENED:
  83                 /*
  84                  * Posix implies any signal should be delivered
  85                  * first, regardless of whether awakened due
  86                  * to receiving event.
  87                  */
  88                 if (!catch) {
  89                         break;
  90                 }
  91                 OS_FALLTHROUGH;
  92         case THREAD_INTERRUPTED:
  93                 if (catch) {
  94                         if (thread_should_abort(self)) {
  95                                 error = EINTR;
  96                         } else if (SHOULDissignal(p, ut)) {
  97                                 if ((sig = CURSIG(p)) != 0) {
  98                                         if (p->p_sigacts->ps_sigintr & sigmask(sig)) {
  99                                                 error = EINTR;
 100                                         } else {
 101                                                 error = ERESTART;
 102                                         }
 103                                 }
 104                                 if (thread_should_abort(self)) {
 105                                         error = EINTR;
 106                                 }
 107                         } else if ((ut->uu_flag & (UT_CANCELDISABLE | UT_CANCEL | UT_CANCELED)) == UT_CANCEL) {
 108                                 /* due to thread cancel */
 109                                 error = EINTR;
 110                         }
 111                 } else {
 112                         error = EINTR;
 113                 }
 114                 break;
 115         }
 116
 117         if (error == EINTR || error == ERESTART) {
 118                 act_set_astbsd(self);
 119         }
 120
 121         if (ut->uu_mtx && !dropmutex) {
 122                 if (spinmutex) {
 123                         lck_mtx_lock_spin(ut->uu_mtx);
 124                 } else {
 125                         lck_mtx_lock(ut->uu_mtx);
 126                 }
 127         }
 128         ut->uu_wchan = NULL;
 129         ut->uu_wmesg = NULL;
 130
 131         unix_syscall_return((*ut->uu_continuation)(error));
 132 }
 133
 134 /*
 135  * Give up the processor till a wakeup occurs
 136  * on chan, at which time the process
 137  * enters the scheduling queue at priority pri.
 138  * The most important effect of pri is that when
 139  * pri<=PZERO a signal cannot disturb the sleep;
 140  * if pri>PZERO signals will be processed.
 141  * If pri&PCATCH is set, signals will cause sleep
 142  * to return 1, rather than longjmp.
 143  * Callers of this routine must be prepared for
 144  * premature return, and check that the reason for
 145  * sleeping has gone away.
 146  *
 147  * if msleep was the entry point, than we have a mutex to deal with
 148  *
 149  * The mutex is unlocked before the caller is blocked, and
 150  * relocked before msleep returns unless the priority includes the PDROP
 151  * flag... if PDROP is specified, _sleep returns with the mutex unlocked
 152  * regardless of whether it actually blocked or not.
 153  */
 154
 155 static int
 156 _sleep(
 157         caddr_t         chan,
 158         int             pri,
 159         const char      *wmsg,
 160         u_int64_t       abstime,
 161         int             (*continuation)(int),
 162         lck_mtx_t       *mtx)
 163 {
 164         struct proc *p;
 165         thread_t self = current_thread();
 166         struct uthread * ut;
 167         int sig, catch;
 168         int dropmutex  = pri & PDROP;
 169         int spinmutex  = pri & PSPIN;
 170         int wait_result;
 171         int error = 0;
 172
 173         ut = get_bsdthread_info(self);
 174
 175         p = current_proc();
 176         p->p_priority = pri & PRIMASK;
 177         /* It can still block in proc_exit() after the teardown. */
 178         if (p->p_stats != NULL) {
 179                 OSIncrementAtomicLong(&p->p_stats->p_ru.ru_nvcsw);
 180         }
 181
 182         if (pri & PCATCH) {
 183                 catch = THREAD_ABORTSAFE;
 184         } else {
 185                 catch = THREAD_UNINT;
 186         }
 187
 188         /* set wait message & channel */
 189         ut->uu_wchan = chan;
 190         ut->uu_wmesg = wmsg ? wmsg : "unknown";
 191
 192         if (mtx != NULL && chan != NULL && (thread_continue_t)continuation == THREAD_CONTINUE_NULL) {
 193                 int     flags;
 194
 195                 if (dropmutex) {
 196                         flags = LCK_SLEEP_UNLOCK;
 197                 } else {
 198                         flags = LCK_SLEEP_DEFAULT;
 199                 }
 200
 201                 if (spinmutex) {
 202                         flags |= LCK_SLEEP_SPIN;
 203                 }
 204
 205                 if (abstime) {
 206                         wait_result = lck_mtx_sleep_deadline(mtx, flags, chan, catch, abstime);
 207                 } else {
 208                         wait_result = lck_mtx_sleep(mtx, flags, chan, catch);
 209                 }
 210         } else {
 211                 if (chan != NULL) {
 212                         assert_wait_deadline(chan, catch, abstime);
 213                 }
 214                 if (mtx) {
 215                         lck_mtx_unlock(mtx);
 216                 }
 217
 218                 if (catch == THREAD_ABORTSAFE) {
 219                         if (SHOULDissignal(p, ut)) {
 220                                 if ((sig = CURSIG(p)) != 0) {
 221                                         if (clear_wait(self, THREAD_INTERRUPTED) == KERN_FAILURE) {
 222                                                 goto block;
 223                                         }
 224                                         if (p->p_sigacts->ps_sigintr & sigmask(sig)) {
 225                                                 error = EINTR;
 226                                         } else {
 227                                                 error = ERESTART;
 228                                         }
 229                                         if (mtx && !dropmutex) {
 230                                                 if (spinmutex) {
 231                                                         lck_mtx_lock_spin(mtx);
 232                                                 } else {
 233                                                         lck_mtx_lock(mtx);
 234                                                 }
 235                                         }
 236                                         goto out;
 237                                 }
 238                         }
 239                         if (thread_should_abort(self)) {
 240                                 if (clear_wait(self, THREAD_INTERRUPTED) == KERN_FAILURE) {
 241                                         goto block;
 242                                 }
 243                                 error = EINTR;
 244
 245                                 if (mtx && !dropmutex) {
 246                                         if (spinmutex) {
 247                                                 lck_mtx_lock_spin(mtx);
 248                                         } else {
 249                                                 lck_mtx_lock(mtx);
 250                                         }
 251                                 }
 252                                 goto out;
 253                         }
 254                 }
 255
 256
 257 block:
 258                 if ((thread_continue_t)continuation != THREAD_CONTINUE_NULL) {
 259                         ut->uu_continuation = continuation;
 260                         ut->uu_pri  = (uint16_t)pri;
 261                         ut->uu_mtx  = mtx;
 262                         (void) thread_block(_sleep_continue);
 263                         /* NOTREACHED */
 264                 }
 265
 266                 wait_result = thread_block(THREAD_CONTINUE_NULL);
 267
 268                 if (mtx && !dropmutex) {
 269                         if (spinmutex) {
 270                                 lck_mtx_lock_spin(mtx);
 271                         } else {
 272                                 lck_mtx_lock(mtx);
 273                         }
 274                 }
 275         }
 276
 277         switch (wait_result) {
 278         case THREAD_TIMED_OUT:
 279                 error = EWOULDBLOCK;
 280                 break;
 281         case THREAD_AWAKENED:
 282         case THREAD_RESTART:
 283                 /*
 284                  * Posix implies any signal should be delivered
 285                  * first, regardless of whether awakened due
 286                  * to receiving event.
 287                  */
 288                 if (catch != THREAD_ABORTSAFE) {
 289                         break;
 290                 }
 291                 OS_FALLTHROUGH;
 292         case THREAD_INTERRUPTED:
 293                 if (catch == THREAD_ABORTSAFE) {
 294                         if (thread_should_abort(self)) {
 295                                 error = EINTR;
 296                         } else if (SHOULDissignal(p, ut)) {
 297                                 if ((sig = CURSIG(p)) != 0) {
 298                                         if (p->p_sigacts->ps_sigintr & sigmask(sig)) {
 299                                                 error = EINTR;
 300                                         } else {
 301                                                 error = ERESTART;
 302                                         }
 303                                 }
 304                                 if (thread_should_abort(self)) {
 305                                         error = EINTR;
 306                                 }
 307                         } else if ((ut->uu_flag & (UT_CANCELDISABLE | UT_CANCEL | UT_CANCELED)) == UT_CANCEL) {
 308                                 /* due to thread cancel */
 309                                 error = EINTR;
 310                         }
 311                 } else {
 312                         error = EINTR;
 313                 }
 314                 break;
 315         }
 316 out:
 317         if (error == EINTR || error == ERESTART) {
 318                 act_set_astbsd(self);
 319         }
 320         ut->uu_wchan = NULL;
 321         ut->uu_wmesg = NULL;
 322
 323         return error;
 324 }
 325
 326 int
 327 sleep(
 328         void    *chan,
 329         int             pri)
 330 {
 331         return _sleep((caddr_t)chan, pri, (char *)NULL, 0, (int (*)(int))0, (lck_mtx_t *)0);
 332 }
 333
 334 int
 335 msleep0(
 336         void            *chan,
 337         lck_mtx_t       *mtx,
 338         int             pri,
 339         const char      *wmsg,
 340         int             timo,
 341         int             (*continuation)(int))
 342 {
 343         u_int64_t       abstime = 0;
 344
 345         if (timo) {
 346                 clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
 347         }
 348
 349         return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation, mtx);
 350 }
 351
 352 int
 353 msleep(
 354         void            *chan,
 355         lck_mtx_t       *mtx,
 356         int             pri,
 357         const char      *wmsg,
 358         struct timespec         *ts)
 359 {
 360         u_int64_t       abstime = 0;
 361
 362         if (ts && (ts->tv_sec || ts->tv_nsec)) {
 363                 nanoseconds_to_absolutetime((uint64_t)ts->tv_sec * NSEC_PER_SEC + ts->tv_nsec, &abstime );
 364                 clock_absolutetime_interval_to_deadline( abstime, &abstime );
 365         }
 366
 367         return _sleep((caddr_t)chan, pri, wmsg, abstime, (int (*)(int))0, mtx);
 368 }
 369
 370 int
 371 msleep1(
 372         void            *chan,
 373         lck_mtx_t       *mtx,
 374         int             pri,
 375         const char      *wmsg,
 376         u_int64_t       abstime)
 377 {
 378         return _sleep((caddr_t)chan, pri, wmsg, abstime, (int (*)(int))0, mtx);
 379 }
 380
 381 int
 382 tsleep(
 383         void            *chan,
 384         int             pri,
 385         const char      *wmsg,
 386         int             timo)
 387 {
 388         u_int64_t       abstime = 0;
 389
 390         if (timo) {
 391                 clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
 392         }
 393         return _sleep((caddr_t)chan, pri, wmsg, abstime, (int (*)(int))0, (lck_mtx_t *)0);
 394 }
 395
 396 int
 397 tsleep0(
 398         void            *chan,
 399         int             pri,
 400         const char      *wmsg,
 401         int             timo,
 402         int             (*continuation)(int))
 403 {
 404         u_int64_t       abstime = 0;
 405
 406         if (timo) {
 407                 clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
 408         }
 409         return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation, (lck_mtx_t *)0);
 410 }
 411
 412 int
 413 tsleep1(
 414         void            *chan,
 415         int             pri,
 416         const char      *wmsg,
 417         u_int64_t       abstime,
 418         int             (*continuation)(int))
 419 {
 420         return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation, (lck_mtx_t *)0);
 421 }
 422
 423 /*
 424  * Wake up all processes sleeping on chan.
 425  */
 426 void
 427 wakeup(void *chan)
 428 {
 429         thread_wakeup((caddr_t)chan);
 430 }
 431
 432 /*
 433  * Wake up the first process sleeping on chan.
 434  *
 435  * Be very sure that the first process is really
 436  * the right one to wakeup.
 437  */
 438 void
 439 wakeup_one(caddr_t chan)
 440 {
 441         thread_wakeup_one((caddr_t)chan);
 442 }
 443
 444 /*
 445  * Compute the priority of a process when running in user mode.
 446  * Arrange to reschedule if the resulting priority is better
 447  * than that of the current process.
 448  */
 449 void
 450 resetpriority(struct proc *p)
 451 {
 452         (void)task_importance(p->task, -p->p_nice);
 453 }
 454
 455 struct loadavg averunnable =
 456 { {0, 0, 0}, FSCALE };                  /* load average, of runnable procs */
 457 /*
 458  * Constants for averages over 1, 5, and 15 minutes
 459  * when sampling at 5 second intervals.
 460  */
 461 static fixpt_t cexp[3] = {
 462         (fixpt_t)(0.9200444146293232 * FSCALE), /* exp(-1/12) */
 463         (fixpt_t)(0.9834714538216174 * FSCALE), /* exp(-1/60) */
 464         (fixpt_t)(0.9944598480048967 * FSCALE), /* exp(-1/180) */
 465 };
 466
 467 void
 468 compute_averunnable(void *arg)
 469 {
 470         unsigned int            nrun = *(unsigned int *)arg;
 471         struct loadavg          *avg = &averunnable;
 472         int             i;
 473
 474         for (i = 0; i < 3; i++) {
 475                 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
 476                     nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
 477         }
 478 }