src/qos.c

   1 /*
   2  * Copyright (c) 2013 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_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. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include "internal.h"
  25
  26 #include <_simple.h>
  27 #include <mach/mach_vm.h>
  28 #include <unistd.h>
  29 #include <spawn.h>
  30 #include <spawn_private.h>
  31 #include <sys/spawn_internal.h>
  32 #include <sys/ulock.h>
  33
  34 // TODO: remove me when internal.h can include *_private.h itself
  35 #include "workqueue_private.h"
  36 #include "qos_private.h"
  37
  38 #define PTHREAD_OVERRIDE_SIGNATURE      (0x6f766572)
  39 #define PTHREAD_OVERRIDE_SIG_DEAD       (0x7265766f)
  40
  41 struct pthread_override_s
  42 {
  43         uint32_t sig;
  44         mach_port_t kthread;
  45         pthread_t pthread;
  46         pthread_priority_t priority;
  47         bool malloced;
  48 };
  49
  50 thread_qos_t
  51 _pthread_qos_class_to_thread_qos(qos_class_t qos)
  52 {
  53         switch (qos) {
  54         case QOS_CLASS_USER_INTERACTIVE: return THREAD_QOS_USER_INTERACTIVE;
  55         case QOS_CLASS_USER_INITIATED: return THREAD_QOS_USER_INITIATED;
  56         case QOS_CLASS_DEFAULT: return THREAD_QOS_LEGACY;
  57         case QOS_CLASS_UTILITY: return THREAD_QOS_UTILITY;
  58         case QOS_CLASS_BACKGROUND: return THREAD_QOS_BACKGROUND;
  59         case QOS_CLASS_MAINTENANCE: return THREAD_QOS_MAINTENANCE;
  60         default: return THREAD_QOS_UNSPECIFIED;
  61         }
  62 }
  63
  64 static inline qos_class_t
  65 _pthread_qos_class_from_thread_qos(thread_qos_t tqos)
  66 {
  67         static const qos_class_t thread_qos_to_qos_class[THREAD_QOS_LAST] = {
  68                 [THREAD_QOS_UNSPECIFIED]      = QOS_CLASS_UNSPECIFIED,
  69                 [THREAD_QOS_MAINTENANCE]      = QOS_CLASS_MAINTENANCE,
  70                 [THREAD_QOS_BACKGROUND]       = QOS_CLASS_BACKGROUND,
  71                 [THREAD_QOS_UTILITY]          = QOS_CLASS_UTILITY,
  72                 [THREAD_QOS_LEGACY]           = QOS_CLASS_DEFAULT,
  73                 [THREAD_QOS_USER_INITIATED]   = QOS_CLASS_USER_INITIATED,
  74                 [THREAD_QOS_USER_INTERACTIVE] = QOS_CLASS_USER_INTERACTIVE,
  75         };
  76         if (os_unlikely(tqos >= THREAD_QOS_LAST)) return QOS_CLASS_UNSPECIFIED;
  77         return thread_qos_to_qos_class[tqos];
  78 }
  79
  80 static inline thread_qos_t
  81 _pthread_validate_qos_class_and_relpri(qos_class_t qc, int relpri)
  82 {
  83         if (relpri > 0 || relpri < QOS_MIN_RELATIVE_PRIORITY) {
  84                 return THREAD_QOS_UNSPECIFIED;
  85         }
  86         return _pthread_qos_class_to_thread_qos(qc);
  87 }
  88
  89 static inline void
  90 _pthread_priority_split(pthread_priority_t pp, qos_class_t *qc, int *relpri)
  91 {
  92         thread_qos_t qos = _pthread_priority_thread_qos(pp);
  93         if (qc) *qc = _pthread_qos_class_from_thread_qos(qos);
  94         if (relpri) *relpri = _pthread_priority_relpri(pp);
  95 }
  96
  97 void
  98 _pthread_set_main_qos(pthread_priority_t qos)
  99 {
 100         _main_qos = (uint32_t)qos;
 101 }
 102
 103 int
 104 pthread_attr_set_qos_class_np(pthread_attr_t *attr, qos_class_t qc, int relpri)
 105 {
 106         thread_qos_t qos = _pthread_validate_qos_class_and_relpri(qc, relpri);
 107         if (attr->sig != _PTHREAD_ATTR_SIG || attr->schedset) {
 108                 return EINVAL;
 109         }
 110
 111         attr->qosclass = _pthread_priority_make_from_thread_qos(qos, relpri, 0);
 112         attr->qosset = 1;
 113         attr->schedset = 0;
 114         return 0;
 115 }
 116
 117 int
 118 pthread_attr_get_qos_class_np(pthread_attr_t *attr, qos_class_t *qc, int *relpri)
 119 {
 120         if (attr->sig != _PTHREAD_ATTR_SIG) {
 121                 return EINVAL;
 122         }
 123
 124         _pthread_priority_split(attr->qosset ? attr->qosclass : 0, qc, relpri);
 125         return 0;
 126 }
 127
 128 int
 129 pthread_set_qos_class_self_np(qos_class_t qc, int relpri)
 130 {
 131         thread_qos_t qos = _pthread_validate_qos_class_and_relpri(qc, relpri);
 132         if (!qos) {
 133                 return EINVAL;
 134         }
 135
 136         pthread_priority_t pp = _pthread_priority_make_from_thread_qos(qos, relpri, 0);
 137         return _pthread_set_properties_self(_PTHREAD_SET_SELF_QOS_FLAG, pp, 0);
 138 }
 139
 140 int
 141 pthread_set_qos_class_np(pthread_t thread, qos_class_t qc, int relpri)
 142 {
 143         if (thread != pthread_self()) {
 144                 /* The kext now enforces this anyway, if we check here too, it allows us to call
 145                  * _pthread_set_properties_self later if we can.
 146                  */
 147                 return EPERM;
 148         }
 149         return pthread_set_qos_class_self_np(qc, relpri);
 150 }
 151
 152 int
 153 pthread_get_qos_class_np(pthread_t thread, qos_class_t *qc, int *relpri)
 154 {
 155         pthread_priority_t pp = thread->tsd[_PTHREAD_TSD_SLOT_PTHREAD_QOS_CLASS];
 156         _pthread_priority_split(pp, qc, relpri);
 157         return 0;
 158 }
 159
 160 qos_class_t
 161 qos_class_self(void)
 162 {
 163         pthread_priority_t pp;
 164         pp = _pthread_getspecific_direct(_PTHREAD_TSD_SLOT_PTHREAD_QOS_CLASS);
 165         return _pthread_qos_class_from_thread_qos(_pthread_priority_thread_qos(pp));
 166 }
 167
 168 qos_class_t
 169 qos_class_main(void)
 170 {
 171         pthread_priority_t pp = _main_qos;
 172         return _pthread_qos_class_from_thread_qos(_pthread_priority_thread_qos(pp));
 173 }
 174
 175 pthread_priority_t
 176 _pthread_qos_class_encode(qos_class_t qc, int relpri, unsigned long flags)
 177 {
 178         thread_qos_t qos = _pthread_qos_class_to_thread_qos(qc);
 179         return _pthread_priority_make_from_thread_qos(qos, relpri, flags);
 180 }
 181
 182 qos_class_t
 183 _pthread_qos_class_decode(pthread_priority_t pp, int *relpri, unsigned long *flags)
 184 {
 185         qos_class_t qc;
 186         _pthread_priority_split(pp, &qc, relpri);
 187         if (flags) *flags = (pp & _PTHREAD_PRIORITY_FLAGS_MASK);
 188         return qc;
 189 }
 190
 191 // Encode a legacy workqueue API priority into a pthread_priority_t. This API
 192 // is deprecated and can be removed when the simulator no longer uses it.
 193 pthread_priority_t
 194 _pthread_qos_class_encode_workqueue(int queue_priority, unsigned long flags)
 195 {
 196         thread_qos_t qos;
 197         switch (queue_priority) {
 198         case WORKQ_HIGH_PRIOQUEUE:      qos = THREAD_QOS_USER_INTERACTIVE; break;
 199         case WORKQ_DEFAULT_PRIOQUEUE:   qos = THREAD_QOS_LEGACY; break;
 200         case WORKQ_NON_INTERACTIVE_PRIOQUEUE:
 201         case WORKQ_LOW_PRIOQUEUE:       qos = THREAD_QOS_UTILITY; break;
 202         case WORKQ_BG_PRIOQUEUE:        qos = THREAD_QOS_BACKGROUND; break;
 203         default:
 204                 PTHREAD_CLIENT_CRASH(queue_priority, "Invalid priority");
 205         }
 206         return _pthread_priority_make_from_thread_qos(qos, 0, flags);
 207 }
 208
 209 #define _PTHREAD_SET_SELF_OUTSIDE_QOS_SKIP \
 210                 (_PTHREAD_SET_SELF_QOS_FLAG | _PTHREAD_SET_SELF_FIXEDPRIORITY_FLAG | \
 211                  _PTHREAD_SET_SELF_TIMESHARE_FLAG | \
 212                  _PTHREAD_SET_SELF_ALTERNATE_AMX)
 213
 214 int
 215 _pthread_set_properties_self(_pthread_set_flags_t flags,
 216                 pthread_priority_t priority, mach_port_t voucher)
 217 {
 218         pthread_t self = pthread_self();
 219         _pthread_set_flags_t kflags = flags;
 220         int rv = 0;
 221
 222         if (self->wq_outsideqos && (flags & _PTHREAD_SET_SELF_OUTSIDE_QOS_SKIP)) {
 223                 // A number of properties cannot be altered if we are a workloop
 224                 // thread that has outside of QoS properties applied to it.
 225                 kflags &= ~_PTHREAD_SET_SELF_OUTSIDE_QOS_SKIP;
 226                 if (kflags == 0) goto skip;
 227         }
 228
 229         rv = __bsdthread_ctl(BSDTHREAD_CTL_SET_SELF, priority, voucher, kflags);
 230
 231 skip:
 232          // Set QoS TSD if we succeeded, or only failed the voucher portion of the
 233          // call. Additionally, if we skipped setting QoS because of outside-of-QoS
 234          // attributes then we still want to set the TSD in userspace.
 235         if ((flags & _PTHREAD_SET_SELF_QOS_FLAG) != 0) {
 236                 if (rv == 0 || errno == ENOENT) {
 237                         _pthread_setspecific_direct(_PTHREAD_TSD_SLOT_PTHREAD_QOS_CLASS,
 238                                         priority);
 239                 }
 240         }
 241
 242         if (rv) {
 243                 rv = errno;
 244         }
 245         return rv;
 246 }
 247
 248 int
 249 pthread_set_fixedpriority_self(void)
 250 {
 251         return _pthread_set_properties_self(_PTHREAD_SET_SELF_FIXEDPRIORITY_FLAG, 0, 0);
 252 }
 253
 254 int
 255 pthread_set_timeshare_self(void)
 256 {
 257         return _pthread_set_properties_self(_PTHREAD_SET_SELF_TIMESHARE_FLAG, 0, 0);
 258 }
 259
 260 int
 261 pthread_prefer_alternate_amx_self(void)
 262 {
 263         return _pthread_set_properties_self(_PTHREAD_SET_SELF_ALTERNATE_AMX, 0, 0);
 264 }
 265
 266
 267 pthread_override_t
 268 pthread_override_qos_class_start_np(pthread_t thread,  qos_class_t qc, int relpri)
 269 {
 270         pthread_override_t rv;
 271         kern_return_t kr;
 272         thread_qos_t qos;
 273         int res = 0;
 274
 275         /* For now, we don't have access to malloc. So we'll have to vm_allocate this, which means the tiny struct is going
 276          * to use an entire page.
 277          */
 278         bool did_malloc = true;
 279
 280         qos = _pthread_validate_qos_class_and_relpri(qc, relpri);
 281         if (qos == THREAD_QOS_UNSPECIFIED) {
 282                 return (_Nonnull pthread_override_t)NULL;
 283         }
 284
 285         mach_vm_address_t vm_addr = malloc(sizeof(struct pthread_override_s));
 286         if (!vm_addr) {
 287                 vm_addr = vm_page_size;
 288                 did_malloc = false;
 289
 290                 kr = mach_vm_allocate(mach_task_self(), &vm_addr,
 291                                 round_page(sizeof(struct pthread_override_s)),
 292                                 VM_MAKE_TAG(VM_MEMORY_LIBDISPATCH) | VM_FLAGS_ANYWHERE);
 293                 if (kr != KERN_SUCCESS) {
 294                         errno = ENOMEM;
 295                         return (_Nonnull pthread_override_t)NULL;
 296                 }
 297         }
 298
 299         rv = (pthread_override_t)vm_addr;
 300         rv->sig = PTHREAD_OVERRIDE_SIGNATURE;
 301         rv->pthread = thread;
 302         rv->kthread = pthread_mach_thread_np(thread);
 303         rv->priority = _pthread_priority_make_from_thread_qos(qos, relpri, 0);
 304         rv->malloced = did_malloc;
 305
 306         /* To ensure that the kernel port that we keep stays valid, we retain it here. */
 307         kr = mach_port_mod_refs(mach_task_self(), rv->kthread, MACH_PORT_RIGHT_SEND, 1);
 308         if (kr != KERN_SUCCESS) {
 309                 res = EINVAL;
 310         }
 311
 312         if (res == 0) {
 313                 res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_OVERRIDE_START, rv->kthread, rv->priority, (uintptr_t)rv);
 314
 315                 if (res != 0) {
 316                         mach_port_mod_refs(mach_task_self(), rv->kthread, MACH_PORT_RIGHT_SEND, -1);
 317                 }
 318         }
 319
 320         if (res != 0) {
 321                 if (did_malloc) {
 322                         free(rv);
 323                 } else {
 324                         mach_vm_deallocate(mach_task_self(), vm_addr, round_page(sizeof(struct pthread_override_s)));
 325                 }
 326                 rv = NULL;
 327         }
 328         return (_Nonnull pthread_override_t)rv;
 329 }
 330
 331 int
 332 pthread_override_qos_class_end_np(pthread_override_t override)
 333 {
 334         kern_return_t kr;
 335         int res = 0;
 336
 337         /* Double-free is a fault. Swap the signature and check the old one. */
 338         if (_pthread_atomic_xchg_uint32_relaxed(&override->sig, PTHREAD_OVERRIDE_SIG_DEAD) != PTHREAD_OVERRIDE_SIGNATURE) {
 339                 __builtin_trap();
 340         }
 341
 342         /* Always consumes (and deallocates) the pthread_override_t object given. */
 343         res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_OVERRIDE_END, override->kthread, (uintptr_t)override, 0);
 344         if (res == -1) { res = errno; }
 345
 346         /* EFAULT from the syscall means we underflowed. Crash here. */
 347         if (res == EFAULT) {
 348                 // <rdar://problem/17645082> Disable the trap-on-underflow, it doesn't co-exist
 349                 // with dispatch resetting override counts on threads.
 350                 //__builtin_trap();
 351                 res = 0;
 352         }
 353
 354         kr = mach_port_mod_refs(mach_task_self(), override->kthread, MACH_PORT_RIGHT_SEND, -1);
 355         if (kr != KERN_SUCCESS) {
 356                 res = EINVAL;
 357         }
 358
 359         if (override->malloced) {
 360                 free(override);
 361         } else {
 362                 kr = mach_vm_deallocate(mach_task_self(), (mach_vm_address_t)override, round_page(sizeof(struct pthread_override_s)));
 363                 if (kr != KERN_SUCCESS) {
 364                         res = EINVAL;
 365                 }
 366         }
 367
 368         return res;
 369 }
 370
 371 int
 372 _pthread_qos_override_start_direct(mach_port_t thread, pthread_priority_t priority, void *resource)
 373 {
 374         int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_OVERRIDE_START, thread, priority, (uintptr_t)resource);
 375         if (res == -1) { res = errno; }
 376         return res;
 377 }
 378
 379 int
 380 _pthread_qos_override_end_direct(mach_port_t thread, void *resource)
 381 {
 382         int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_OVERRIDE_END, thread, (uintptr_t)resource, 0);
 383         if (res == -1) { res = errno; }
 384         return res;
 385 }
 386
 387 int
 388 _pthread_override_qos_class_start_direct(mach_port_t thread, pthread_priority_t priority)
 389 {
 390         // use pthread_self as the default per-thread memory allocation to track the override in the kernel
 391         return _pthread_qos_override_start_direct(thread, priority, pthread_self());
 392 }
 393
 394 int
 395 _pthread_override_qos_class_end_direct(mach_port_t thread)
 396 {
 397         // use pthread_self as the default per-thread memory allocation to track the override in the kernel
 398         return _pthread_qos_override_end_direct(thread, pthread_self());
 399 }
 400
 401 int
 402 _pthread_workqueue_override_start_direct(mach_port_t thread, pthread_priority_t priority)
 403 {
 404         int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_OVERRIDE_DISPATCH, thread, priority, 0);
 405         if (res == -1) { res = errno; }
 406         return res;
 407 }
 408
 409 int
 410 _pthread_workqueue_override_start_direct_check_owner(mach_port_t thread, pthread_priority_t priority, mach_port_t *ulock_addr)
 411 {
 412 #if !TARGET_OS_IPHONE
 413         static boolean_t kernel_supports_owner_check = TRUE;
 414         if (!kernel_supports_owner_check) {
 415                 ulock_addr = NULL;
 416         }
 417 #endif
 418
 419         for (;;) {
 420                 int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_OVERRIDE_DISPATCH, thread, priority, ulock_addr);
 421                 if (res == -1) { res = errno; }
 422 #if !TARGET_OS_IPHONE
 423                 if (ulock_addr && res == EINVAL) {
 424                         if ((uintptr_t)ulock_addr % _Alignof(_Atomic uint32_t)) {
 425                                 // do not mute bad ulock addresses related errors
 426                                 return EINVAL;
 427                         }
 428                         // backward compatibility for the XBS chroot
 429                         // BSDTHREAD_CTL_QOS_OVERRIDE_DISPATCH used to return EINVAL if
 430                         // arg3 was non NULL.
 431                         kernel_supports_owner_check = FALSE;
 432                         ulock_addr = NULL;
 433                         continue;
 434                 }
 435 #endif
 436                 if (ulock_addr && res == EFAULT) {
 437                         // kernel wants us to redrive the call, so while we refault the
 438                         // memory, also revalidate the owner
 439                         uint32_t uval = *(uint32_t volatile *)ulock_addr;
 440                         if (ulock_owner_value_to_port_name(uval) != thread) {
 441                                 return ESTALE;
 442                         }
 443                         continue;
 444                 }
 445
 446                 return res;
 447         }
 448 }
 449
 450 int
 451 _pthread_workqueue_override_reset(void)
 452 {
 453         int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_OVERRIDE_RESET, 0, 0, 0);
 454         if (res == -1) { res = errno; }
 455         return res;
 456 }
 457
 458 int
 459 _pthread_workqueue_asynchronous_override_add(mach_port_t thread, pthread_priority_t priority, void *resource)
 460 {
 461         int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_DISPATCH_ASYNCHRONOUS_OVERRIDE_ADD, thread, priority, (uintptr_t)resource);
 462         if (res == -1) { res = errno; }
 463         return res;
 464 }
 465
 466 int
 467 _pthread_workqueue_asynchronous_override_reset_self(void *resource)
 468 {
 469         int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_DISPATCH_ASYNCHRONOUS_OVERRIDE_RESET,
 470                                                           0 /* !reset_all */,
 471                                                           (uintptr_t)resource,
 472                                                           0);
 473         if (res == -1) { res = errno; }
 474         return res;
 475 }
 476
 477 int
 478 _pthread_workqueue_asynchronous_override_reset_all_self(void)
 479 {
 480         int res = __bsdthread_ctl(BSDTHREAD_CTL_QOS_DISPATCH_ASYNCHRONOUS_OVERRIDE_RESET,
 481                                                           1 /* reset_all */,
 482                                                           0,
 483                                                           0);
 484         if (res == -1) { res = errno; }
 485         return res;
 486 }
 487
 488 static inline uint16_t
 489 _pthread_workqueue_parallelism_for_priority(int qos, unsigned long flags)
 490 {
 491         int rc = __bsdthread_ctl(BSDTHREAD_CTL_QOS_MAX_PARALLELISM, qos, flags, 0);
 492         if (os_unlikely(rc == -1)) {
 493                 rc = errno;
 494                 if (rc != EINVAL) {
 495                         PTHREAD_INTERNAL_CRASH(rc, "qos_max_parallelism failed");
 496                 }
 497                 if (flags & _PTHREAD_QOS_PARALLELISM_COUNT_LOGICAL) {
 498                         return *(uint8_t *)_COMM_PAGE_LOGICAL_CPUS;
 499                 } else {
 500                         return *(uint8_t *)_COMM_PAGE_PHYSICAL_CPUS;
 501                 }
 502         }
 503         return (uint16_t)rc;
 504 }
 505
 506 int
 507 pthread_qos_max_parallelism(qos_class_t qos, unsigned long flags)
 508 {
 509         thread_qos_t thread_qos;
 510         if (qos == QOS_CLASS_UNSPECIFIED) {
 511                 qos = QOS_CLASS_DEFAULT; // <rdar://problem/35080198>
 512         }
 513         thread_qos = _pthread_qos_class_to_thread_qos(qos);
 514         if (thread_qos == THREAD_QOS_UNSPECIFIED) {
 515                 errno = EINVAL;
 516                 return -1;
 517         }
 518
 519         unsigned long syscall_flags = _PTHREAD_QOS_PARALLELISM_COUNT_LOGICAL;
 520         uint16_t *ptr = &_pthread_globals()->qmp_logical[thread_qos];
 521
 522         if (flags & PTHREAD_MAX_PARALLELISM_PHYSICAL) {
 523                 syscall_flags = 0;
 524                 ptr = &_pthread_globals()->qmp_physical[thread_qos];
 525         }
 526         if (*ptr == 0) {
 527                 *ptr = _pthread_workqueue_parallelism_for_priority(thread_qos, syscall_flags);
 528         }
 529         return *ptr;
 530 }
 531
 532 int
 533 pthread_time_constraint_max_parallelism(unsigned long flags)
 534 {
 535         unsigned long syscall_flags = _PTHREAD_QOS_PARALLELISM_COUNT_LOGICAL;
 536         uint16_t *ptr = &_pthread_globals()->qmp_logical[0];
 537
 538         if (flags & PTHREAD_MAX_PARALLELISM_PHYSICAL) {
 539                 syscall_flags = 0;
 540                 ptr = &_pthread_globals()->qmp_physical[0];
 541         }
 542         if (*ptr == 0) {
 543                 *ptr = _pthread_workqueue_parallelism_for_priority(0,
 544                                 syscall_flags | _PTHREAD_QOS_PARALLELISM_REALTIME);
 545         }
 546         return *ptr;
 547 }
 548
 549 int
 550 posix_spawnattr_set_qos_class_np(posix_spawnattr_t * __restrict __attr, qos_class_t __qos_class)
 551 {
 552         switch (__qos_class) {
 553                 case QOS_CLASS_UTILITY:
 554                         return posix_spawnattr_set_qos_clamp_np(__attr, POSIX_SPAWN_PROC_CLAMP_UTILITY);
 555                 case QOS_CLASS_BACKGROUND:
 556                         return posix_spawnattr_set_qos_clamp_np(__attr, POSIX_SPAWN_PROC_CLAMP_BACKGROUND);
 557                 case QOS_CLASS_MAINTENANCE:
 558                         return posix_spawnattr_set_qos_clamp_np(__attr, POSIX_SPAWN_PROC_CLAMP_MAINTENANCE);
 559                 default:
 560                         return EINVAL;
 561         }
 562 }
 563
 564 int
 565 posix_spawnattr_get_qos_class_np(const posix_spawnattr_t *__restrict __attr, qos_class_t * __restrict __qos_class)
 566 {
 567         uint64_t clamp;
 568
 569         if (!__qos_class) {
 570                 return EINVAL;
 571         }
 572
 573         int rv = posix_spawnattr_get_qos_clamp_np(__attr, &clamp);
 574         if (rv != 0) {
 575                 return rv;
 576         }
 577
 578         switch (clamp) {
 579                 case POSIX_SPAWN_PROC_CLAMP_UTILITY:
 580                         *__qos_class = QOS_CLASS_UTILITY;
 581                         break;
 582                 case POSIX_SPAWN_PROC_CLAMP_BACKGROUND:
 583                         *__qos_class = QOS_CLASS_BACKGROUND;
 584                         break;
 585                 case POSIX_SPAWN_PROC_CLAMP_MAINTENANCE:
 586                         *__qos_class = QOS_CLASS_MAINTENANCE;
 587                         break;
 588                 default:
 589                         *__qos_class = QOS_CLASS_UNSPECIFIED;
 590                         break;
 591         }
 592
 593         return 0;
 594 }