guestfs_abort_cb guestfs_add_cdrom guestfs_add_drive guestfs_add_drive_opts guestfs_add_drive_opts_argv guestfs_add_drive_opts_va guestfs_add_drive_ro guestfs_add_drive_ro_with_if guestfs_add_drive_with_if guestfs_aug_clear guestfs_aug_close guestfs_aug_defnode guestfs_aug_defvar guestfs_aug_get guestfs_aug_init guestfs_aug_insert guestfs_aug_load guestfs_aug_ls guestfs_aug_match guestfs_aug_mv guestfs_aug_rm guestfs_aug_save guestfs_aug_set guestfs_available guestfs_available_all_groups guestfs_base64_in guestfs_base64_out guestfs_blockdev_flushbufs guestfs_blockdev_getbsz guestfs_blockdev_getro guestfs_blockdev_getsize64 guestfs_blockdev_getss guestfs_blockdev_getsz guestfs_blockdev_rereadpt guestfs_blockdev_setbsz guestfs_blockdev_setro guestfs_blockdev_setrw guestfs_case_sensitive_path guestfs_cat guestfs_checksum guestfs_checksum_device guestfs_checksums_out guestfs_chmod guestfs_chown guestfs_close guestfs_close_cb guestfs_command guestfs_command_lines guestfs_config guestfs_copy_size guestfs_cp guestfs_cp_a guestfs_create guestfs_dd guestfs_debug guestfs_debug_upload guestfs_df guestfs_df_h guestfs_dirent guestfs_dirent_list guestfs_dmesg guestfs_download guestfs_download_offset guestfs_drop_caches guestfs_du guestfs_e2fsck_f guestfs_echo_daemon guestfs_egrep guestfs_egrepi guestfs_equal guestfs_error_errno guestfs_error_handler_cb guestfs_exists guestfs_fallocate guestfs_fallocate64 guestfs_fgrep guestfs_fgrepi guestfs_file guestfs_file_architecture guestfs_filesize guestfs_fill guestfs_fill_pattern guestfs_find guestfs_find0 guestfs_findfs_label guestfs_findfs_uuid guestfs_fsck guestfs_get_append guestfs_get_autosync guestfs_getcon guestfs_get_direct guestfs_get_e2label guestfs_get_e2uuid guestfs_get_error_handler guestfs_get_memsize guestfs_get_network guestfs_get_out_of_memory_handler guestfs_get_path guestfs_get_pid guestfs_get_private guestfs_get_qemu guestfs_get_recovery_proc guestfs_get_selinux guestfs_get_state guestfs_get_trace guestfs_get_umask guestfs_get_verbose guestfs_getxattrs guestfs_glob_expand guestfs_grep guestfs_grepi guestfs_grub_install guestfs_head guestfs_head_n guestfs_hexdump guestfs_initrd_cat guestfs_initrd_list guestfs_inotify_add_watch guestfs_inotify_close guestfs_inotify_event guestfs_inotify_event_list guestfs_inotify_files guestfs_inotify_init guestfs_inotify_read guestfs_inotify_rm_watch guestfs_inspect_get_arch guestfs_inspect_get_distro guestfs_inspect_get_filesystems guestfs_inspect_get_major_version guestfs_inspect_get_minor_version guestfs_inspect_get_mountpoints guestfs_inspect_get_product_name guestfs_inspect_get_roots guestfs_inspect_get_type guestfs_inspect_get_windows_systemroot guestfs_inspect_os guestfs_int_bool guestfs_int_bool_list guestfs_int_dirent guestfs_int_dirent_list guestfs_int_inotify_event guestfs_int_inotify_event_list guestfs_int_int_bool guestfs_int_int_bool_list guestfs_int_lvm_lv guestfs_int_lvm_lv_list guestfs_int_lvm_pv guestfs_int_lvm_pv_list guestfs_int_lvm_vg guestfs_int_lvm_vg_list guestfs_int_partition guestfs_int_partition_list guestfs_int_stat guestfs_int_stat_list guestfs_int_statvfs guestfs_int_statvfs_list guestfs_int_version guestfs_int_version_list guestfs_int_xattr guestfs_int_xattr_list guestfs_is_blockdev guestfs_is_busy guestfs_is_chardev guestfs_is_config guestfs_is_dir guestfs_is_fifo guestfs_is_file guestfs_is_launching guestfs_is_lv guestfs_is_ready guestfs_is_socket guestfs_is_symlink guestfs_kill_subprocess guestfs_last_errno guestfs_last_error guestfs_launch guestfs_launch_done_cb guestfs_lchown guestfs_lgetxattrs guestfs_list_devices guestfs_list_filesystems guestfs_list_partitions guestfs_ll guestfs_ln guestfs_ln_f guestfs_ln_s guestfs_ln_sf guestfs_log_message_cb guestfs_lremovexattr guestfs_ls guestfs_lsetxattr guestfs_lstat guestfs_lstatlist guestfs_luks_add_key guestfs_luks_close guestfs_luks_format guestfs_luks_format_cipher guestfs_luks_kill_slot guestfs_luks_open guestfs_luks_open_ro guestfs_lvcreate guestfs_lvm_canonical_lv_name guestfs_lvm_clear_filter guestfs_lvm_lv guestfs_lvm_lv_list guestfs_lvm_pv guestfs_lvm_pv_list guestfs_lvm_remove_all guestfs_lvm_set_filter guestfs_lvm_vg guestfs_lvm_vg_list guestfs_lvremove guestfs_lvrename guestfs_lvresize guestfs_lvresize_free guestfs_lvs guestfs_lvs_full guestfs_lvuuid guestfs_lxattrlist guestfs_mkdir guestfs_mkdir_mode guestfs_mkdir_p guestfs_mkdtemp guestfs_mke2fs_J guestfs_mke2fs_JL guestfs_mke2fs_JU guestfs_mke2journal guestfs_mke2journal_L guestfs_mke2journal_U guestfs_mkfifo guestfs_mkfs guestfs_mkfs_b guestfs_mkmountpoint guestfs_mknod guestfs_mknod_b guestfs_mknod_c guestfs_mkswap guestfs_mkswap_file guestfs_mkswap_L guestfs_mkswap_U guestfs_modprobe guestfs_mount guestfs_mount_loop guestfs_mount_options guestfs_mountpoints guestfs_mount_ro guestfs_mounts guestfs_mount_vfs guestfs_mv guestfs_ntfs_3g_probe guestfs_ntfsresize guestfs_ntfsresize_size guestfs_part_add guestfs_part_del guestfs_part_disk guestfs_part_get_bootable guestfs_part_get_mbr_id guestfs_part_get_parttype guestfs_part_init guestfs_partition guestfs_partition_list guestfs_part_list guestfs_part_set_bootable guestfs_part_set_mbr_id guestfs_part_set_name guestfs_part_to_dev guestfs_perrorf guestfs_ping_daemon guestfs_pread guestfs_pread_device guestfs_progress_cb guestfs_protocol guestfs_pvcreate guestfs_pvremove guestfs_pvresize guestfs_pvresize_size guestfs_pvs guestfs_pvs_full guestfs_pvuuid guestfs_pwrite guestfs_pwrite_device guestfs_readdir guestfs_read_file guestfs_read_lines guestfs_readlink guestfs_readlinklist guestfs_realpath guestfs_removexattr guestfs_resize2fs guestfs_resize2fs_size guestfs_rm guestfs_rmdir guestfs_rmmountpoint guestfs_rm_rf guestfs_safe_calloc guestfs_safe_malloc guestfs_safe_memdup guestfs_safe_realloc guestfs_safe_strdup guestfs_safe_strndup guestfs_scrub_device guestfs_scrub_file guestfs_scrub_freespace guestfs_set_append guestfs_set_autosync guestfs_set_close_callback guestfs_setcon guestfs_set_direct guestfs_set_e2label guestfs_set_e2uuid guestfs_set_error_handler guestfs_set_launch_done_callback guestfs_set_log_message_callback guestfs_set_memsize guestfs_set_network guestfs_set_out_of_memory_handler guestfs_set_path guestfs_set_private guestfs_set_progress_callback guestfs_set_qemu guestfs_set_recovery_proc guestfs_set_selinux guestfs_set_subprocess_quit_callback guestfs_set_trace guestfs_set_verbose guestfs_setxattr guestfs_sfdisk guestfs_sfdisk_disk_geometry guestfs_sfdisk_kernel_geometry guestfs_sfdisk_l guestfs_sfdiskM guestfs_sfdisk_N guestfs_sh guestfs_sh_lines guestfs_sleep guestfs_stat guestfs_stat_list guestfs_statvfs guestfs_statvfs_list guestfs_strings guestfs_strings_e guestfs_subprocess_quit_cb guestfs_swapoff_device guestfs_swapoff_file guestfs_swapoff_label guestfs_swapoff_uuid guestfs_swapon_device guestfs_swapon_file guestfs_swapon_label guestfs_swapon_uuid guestfs_sync guestfs_tail guestfs_tail_n guestfs_tar_in guestfs_tar_out guestfs_tgz_in guestfs_tgz_out guestfs_touch guestfs_truncate guestfs_truncate_size guestfs_tune2fs_l guestfs_txz_in guestfs_txz_out guestfs_umask guestfs_umount guestfs_umount_all guestfs_upload guestfs_upload_offset guestfs_utimens guestfs_version guestfs_version_list guestfs_vfs_label guestfs_vfs_type guestfs_vfs_uuid guestfs_vg_activate guestfs_vg_activate_all guestfs_vgcreate guestfs_vglvuuids guestfs_vgpvuuids guestfs_vgremove guestfs_vgrename guestfs_vgs guestfs_vgscan guestfs_vgs_full guestfs_vguuid guestfs_wait_ready guestfs_wc_c guestfs_wc_l guestfs_wc_w guestfs_write guestfs_write_file guestfs_xattr guestfs_xattr_list guestfs_zegrep guestfs_zegrepi guestfs_zero guestfs_zero_device guestfs_zerofree guestfs_zfgrep guestfs_zfgrepi guestfs_zfile guestfs_zgrep guestfs_zgrepi ' href='#n105'>105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 
/*
 * Implement CPU time clocks for the POSIX clock interface.
 */

#include <linux/sched.h>
#include <linux/posix-timers.h>
#include <asm/uaccess.h>
#include <linux/errno.h>

static int check_clock(const clockid_t which_clock)
{
	int error = 0;
	struct task_struct *p;
	const pid_t pid = CPUCLOCK_PID(which_clock);

	if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
		return -EINVAL;

	if (pid == 0)
		return 0;

	read_lock(&tasklist_lock);
	p = find_task_by_pid(pid);
	if (!p || (CPUCLOCK_PERTHREAD(which_clock) ?
		   p->tgid != current->tgid : p->tgid != pid)) {
		error = -EINVAL;
	}
	read_unlock(&tasklist_lock);

	return error;
}

static inline union cpu_time_count
timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
{
	union cpu_time_count ret;
	ret.sched = 0;		/* high half always zero when .cpu used */
	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
		ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
	} else {
		ret.cpu = timespec_to_cputime(tp);
	}
	return ret;
}

static void sample_to_timespec(const clockid_t which_clock,
			       union cpu_time_count cpu,
			       struct timespec *tp)
{
	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
		tp->tv_sec = div_long_long_rem(cpu.sched,
					       NSEC_PER_SEC, &tp->tv_nsec);
	} else {
		cputime_to_timespec(cpu.cpu, tp);
	}
}

static inline int cpu_time_before(const clockid_t which_clock,
				  union cpu_time_count now,
				  union cpu_time_count then)
{
	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
		return now.sched < then.sched;
	}  else {
		return cputime_lt(now.cpu, then.cpu);
	}
}
static inline void cpu_time_add(const clockid_t which_clock,
				union cpu_time_count *acc,
			        union cpu_time_count val)
{
	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
		acc->sched += val.sched;
	}  else {
		acc->cpu = cputime_add(acc->cpu, val.cpu);
	}
}
static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
						union cpu_time_count a,
						union cpu_time_count b)
{
	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
		a.sched -= b.sched;
	}  else {
		a.cpu = cputime_sub(a.cpu, b.cpu);
	}
	return a;
}

/*
 * Divide and limit the result to res >= 1
 *
 * This is necessary to prevent signal delivery starvation, when the result of
 * the division would be rounded down to 0.
 */
static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
{
	cputime_t res = cputime_div(time, div);

	return max_t(cputime_t, res, 1);
}

/*
 * Update expiry time from increment, and increase overrun count,
 * given the current clock sample.
 */
static void bump_cpu_timer(struct k_itimer *timer,
				  union cpu_time_count now)
{
	int i;

	if (timer->it.cpu.incr.sched == 0)
		return;

	if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
		unsigned long long delta, incr;

		if (now.sched < timer->it.cpu.expires.sched)
			return;
		incr = timer->it.cpu.incr.sched;
		delta = now.sched + incr - timer->it.cpu.expires.sched;
		/* Don't use (incr*2 < delta), incr*2 might overflow. */
		for (i = 0; incr < delta - incr; i++)
			incr = incr << 1;
		for (; i >= 0; incr >>= 1, i--) {
			if (delta < incr)
				continue;
			timer->it.cpu.expires.sched += incr;
			timer->it_overrun += 1 << i;
			delta -= incr;
		}
	} else {
		cputime_t delta, incr;

		if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
			return;
		incr = timer->it.cpu.incr.cpu;
		delta = cputime_sub(cputime_add(now.cpu, incr),
				    timer->it.cpu.expires.cpu);
		/* Don't use (incr*2 < delta), incr*2 might overflow. */
		for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
			     incr = cputime_add(incr, incr);
		for (; i >= 0; incr = cputime_halve(incr), i--) {
			if (cputime_lt(delta, incr))
				continue;
			timer->it.cpu.expires.cpu =
				cputime_add(timer->it.cpu.expires.cpu, incr);
			timer->it_overrun += 1 << i;
			delta = cputime_sub(delta, incr);
		}
	}
}

static inline cputime_t prof_ticks(struct task_struct *p)
{
	return cputime_add(p->utime, p->stime);
}
static inline cputime_t virt_ticks(struct task_struct *p)
{
	return p->utime;
}
static inline unsigned long long sched_ns(struct task_struct *p)
{
	return (p == current) ? current_sched_time(p) : p->sched_time;
}

int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
{
	int error = check_clock(which_clock);
	if (!error) {
		tp->tv_sec = 0;
		tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
		if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
			/*
			 * If sched_clock is using a cycle counter, we
			 * don't have any idea of its true resolution
			 * exported, but it is much more than 1s/HZ.
			 */
			tp->tv_nsec = 1;
		}
	}
	return error;
}

int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
{
	/*
	 * You can never reset a CPU clock, but we check for other errors
	 * in the call before failing with EPERM.
	 */
	int error = check_clock(which_clock);
	if (error == 0) {
		error = -EPERM;
	}
	return error;
}


/*
 * Sample a per-thread clock for the given task.
 */
static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
			    union cpu_time_count *cpu)
{
	switch (CPUCLOCK_WHICH(which_clock)) {
	default:
		return -EINVAL;
	case CPUCLOCK_PROF:
		cpu->cpu = prof_ticks(p);
		break;
	case CPUCLOCK_VIRT:
		cpu->cpu = virt_ticks(p);
		break;
	case CPUCLOCK_SCHED:
		cpu->sched = sched_ns(p);
		break;
	}
	return 0;
}

/*
 * Sample a process (thread group) clock for the given group_leader task.
 * Must be called with tasklist_lock held for reading.
 * Must be called with tasklist_lock held for reading, and p->sighand->siglock.
 */
static int cpu_clock_sample_group_locked(unsigned int clock_idx,
					 struct task_struct *p,
					 union cpu_time_count *cpu)
{
	struct task_struct *t = p;
 	switch (clock_idx) {
	default:
		return -EINVAL;
	case CPUCLOCK_PROF:
		cpu->cpu = cputime_add(p->signal->utime, p->signal->stime);
		do {
			cpu->cpu = cputime_add(cpu->cpu, prof_ticks(t));
			t = next_thread(t);
		} while (t != p);
		break;
	case CPUCLOCK_VIRT:
		cpu->cpu = p->signal->utime;
		do {
			cpu->cpu = cputime_add(cpu->cpu, virt_ticks(t));
			t = next_thread(t);
		} while (t != p);
		break;
	case CPUCLOCK_SCHED:
		cpu->sched = p->signal->sched_time;
		/* Add in each other live thread.  */
		while ((t = next_thread(t)) != p) {
			cpu->sched += t->sched_time;
		}
		cpu->sched += sched_ns(p);
		break;
	}
	return 0;
}

/*
 * Sample a process (thread group) clock for the given group_leader task.
 * Must be called with tasklist_lock held for reading.
 */
static int cpu_clock_sample_group(const clockid_t which_clock,
				  struct task_struct *p,
				  union cpu_time_count *cpu)
{
	int ret;
	unsigned long flags;
	spin_lock_irqsave(&p->sighand->siglock, flags);
	ret = cpu_clock_sample_group_locked(CPUCLOCK_WHICH(which_clock), p,
					    cpu);
	spin_unlock_irqrestore(&p->sighand->siglock, flags);
	return ret;
}


int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
{
	const pid_t pid = CPUCLOCK_PID(which_clock);
	int error = -EINVAL;
	union cpu_time_count rtn;

	if (pid == 0) {
		/*
		 * Special case constant value for our own clocks.
		 * We don't have to do any lookup to find ourselves.
		 */
		if (CPUCLOCK_PERTHREAD(which_clock)) {
			/*
			 * Sampling just ourselves we can do with no locking.
			 */
			error = cpu_clock_sample(which_clock,
						 current, &rtn);
		} else {
			read_lock(&tasklist_lock);
			error = cpu_clock_sample_group(which_clock,
						       current, &rtn);
			read_unlock(&tasklist_lock);
		}
	} else {
		/*
		 * Find the given PID, and validate that the caller
		 * should be able to see it.
		 */
		struct task_struct *p;
		rcu_read_lock();
		p = find_task_by_pid(pid);
		if (p) {
			if (CPUCLOCK_PERTHREAD(which_clock)) {
				if (p->tgid == current->tgid) {
					error = cpu_clock_sample(which_clock,
								 p, &rtn);
				}
			} else {
				read_lock(&tasklist_lock);
				if (p->tgid == pid && p->signal) {
					error =
					    cpu_clock_sample_group(which_clock,
							           p, &rtn);
				}
				read_unlock(&tasklist_lock);
			}
		}
		rcu_read_unlock();
	}

	if (error)
		return error;
	sample_to_timespec(which_clock, rtn, tp);
	return 0;
}


/*
 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
 * This is called from sys_timer_create with the new timer already locked.
 */
int posix_cpu_timer_create(struct k_itimer *new_timer)
{
	int ret = 0;
	const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
	struct task_struct *p;

	if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
		return -EINVAL;

	INIT_LIST_HEAD(&new_timer->it.cpu.entry);
	new_timer->it.cpu.incr.sched = 0;
	new_timer->it.cpu.expires.sched = 0;

	read_lock(&tasklist_lock);
	if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
		if (pid == 0) {
			p = current;
		} else {
			p = find_task_by_pid(pid);
			if (p && p->tgid != current->tgid)
				p = NULL;
		}
	} else {
		if (pid == 0) {
			p = current->group_leader;
		} else {
			p = find_task_by_pid(pid);
			if (p && p->tgid != pid)
				p = NULL;
		}
	}
	new_timer->it.cpu.task = p;
	if (p) {
		get_task_struct(p);
	} else {
		ret = -EINVAL;
	}
	read_unlock(&tasklist_lock);

	return ret;
}

/*
 * Clean up a CPU-clock timer that is about to be destroyed.
 * This is called from timer deletion with the timer already locked.
 * If we return TIMER_RETRY, it's necessary to release the timer's lock
 * and try again.  (This happens when the timer is in the middle of firing.)
 */
int posix_cpu_timer_del(struct k_itimer *timer)
{
	struct task_struct *p = timer->it.cpu.task;
	int ret = 0;

	if (likely(p != NULL)) {
		read_lock(&tasklist_lock);
		if (unlikely(p->signal == NULL)) {
			/*
			 * We raced with the reaping of the task.
			 * The deletion should have cleared us off the list.
			 */
			BUG_ON(!list_empty(&timer->it.cpu.entry));
		} else {
			spin_lock(&p->sighand->siglock);
			if (timer->it.cpu.firing)
				ret = TIMER_RETRY;
			else
				list_del(&timer->it.cpu.entry);
			spin_unlock(&p->sighand->siglock);
		}
		read_unlock(&tasklist_lock);

		if (!ret)
			put_task_struct(p);
	}

	return ret;
}

/*
 * Clean out CPU timers still ticking when a thread exited.  The task
 * pointer is cleared, and the expiry time is replaced with the residual
 * time for later timer_gettime calls to return.
 * This must be called with the siglock held.
 */
static void cleanup_timers(struct list_head *head,
			   cputime_t utime, cputime_t stime,
			   unsigned long long sched_time)
{
	struct cpu_timer_list *timer, *next;
	cputime_t ptime = cputime_add(utime, stime);

	list_for_each_entry_safe(timer, next, head, entry) {
		list_del_init(&timer->entry);
		if (cputime_lt(timer->expires.cpu, ptime)) {
			timer->expires.cpu = cputime_zero;
		} else {
			timer->expires.cpu = cputime_sub(timer->expires.cpu,
							 ptime);
		}
	}

	++head;
	list_for_each_entry_safe(timer, next, head, entry) {
		list_del_init(&timer->entry);
		if (cputime_lt(timer->expires.cpu, utime)) {