1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * taskset - retrieve or set a processes' CPU affinity
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4 | * Copyright (c) 2006 Bernhard Reutner-Fischer
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5 | *
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6 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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7 | */
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8 |
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9 | //config:config TASKSET
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10 | //config: bool "taskset"
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11 | //config: default n # doesn't build on some non-x86 targets (m68k)
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12 | //config: help
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13 | //config: Retrieve or set a processes's CPU affinity.
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14 | //config: This requires sched_{g,s}etaffinity support in your libc.
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15 | //config:
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16 | //config:config FEATURE_TASKSET_FANCY
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17 | //config: bool "Fancy output"
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18 | //config: default y
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19 | //config: depends on TASKSET
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20 | //config: help
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21 | //config: Add code for fancy output. This merely silences a compiler-warning
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22 | //config: and adds about 135 Bytes. May be needed for machines with alot
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23 | //config: of CPUs.
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24 |
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25 | //applet:IF_TASKSET(APPLET(taskset, BB_DIR_USR_BIN, BB_SUID_DROP))
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26 | //kbuild:lib-$(CONFIG_TASKSET) += taskset.o
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27 |
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28 | //usage:#define taskset_trivial_usage
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29 | //usage: "[-p] [MASK] [PID | PROG ARGS]"
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30 | //usage:#define taskset_full_usage "\n\n"
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31 | //usage: "Set or get CPU affinity\n"
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32 | //usage: "\n -p Operate on an existing PID"
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33 | //usage:
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34 | //usage:#define taskset_example_usage
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35 | //usage: "$ taskset 0x7 ./dgemm_test&\n"
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36 | //usage: "$ taskset -p 0x1 $!\n"
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37 | //usage: "pid 4790's current affinity mask: 7\n"
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38 | //usage: "pid 4790's new affinity mask: 1\n"
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39 | //usage: "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
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40 | //usage: "pid 6671's current affinity mask: 1\n"
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41 | //usage: "pid 6671's new affinity mask: 1\n"
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42 | //usage: "$ taskset -p 1\n"
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43 | //usage: "pid 1's current affinity mask: 3\n"
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44 | /*
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45 | Not yet implemented:
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46 | * -a/--all-tasks (affect all threads)
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47 | * -c/--cpu-list (specify CPUs via "1,3,5-7")
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48 | */
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49 |
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50 | #include <sched.h>
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51 | #include "libbb.h"
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52 |
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53 | #if ENABLE_FEATURE_TASKSET_FANCY
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54 | #define TASKSET_PRINTF_MASK "%s"
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55 | /* craft a string from the mask */
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56 | static char *from_cpuset(cpu_set_t *mask)
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57 | {
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58 | int i;
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59 | char *ret = NULL;
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60 | char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
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61 |
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62 | for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
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63 | int val = 0;
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64 | int off;
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65 | for (off = 0; off <= 3; ++off)
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66 | if (CPU_ISSET(i + off, mask))
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67 | val |= 1 << off;
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68 | if (!ret && val)
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69 | ret = str;
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70 | *str++ = bb_hexdigits_upcase[val] | 0x20;
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71 | }
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72 | return ret;
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73 | }
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74 | #else
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75 | #define TASKSET_PRINTF_MASK "%llx"
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76 | static unsigned long long from_cpuset(cpu_set_t *mask)
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77 | {
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78 | BUILD_BUG_ON(CPU_SETSIZE < 8*sizeof(int));
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79 |
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80 | /* Take the least significant bits. Assume cpu_set_t is
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81 | * implemented as an array of unsigned long or unsigned
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82 | * int.
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83 | */
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84 | if (CPU_SETSIZE < 8*sizeof(long))
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85 | return *(unsigned*)mask;
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86 | if (CPU_SETSIZE < 8*sizeof(long long))
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87 | return *(unsigned long*)mask;
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88 | # if BB_BIG_ENDIAN
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89 | if (sizeof(long long) > sizeof(long)) {
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90 | /* We can put two long in the long long, but they have to
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91 | * be swapped: the least significant word comes first in the
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92 | * array */
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93 | unsigned long *p = (void*)mask;
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94 | return p[0] + ((unsigned long long)p[1] << (8*sizeof(long)));
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95 | }
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96 | # endif
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97 | return *(unsigned long long*)mask;
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98 | }
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99 | #endif
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100 |
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101 |
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102 | int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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103 | int taskset_main(int argc UNUSED_PARAM, char **argv)
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104 | {
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105 | cpu_set_t mask;
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106 | pid_t pid = 0;
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107 | unsigned opt_p;
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108 | const char *current_new;
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109 | char *pid_str;
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110 | char *aff = aff; /* for compiler */
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111 |
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112 | /* NB: we mimic util-linux's taskset: -p does not take
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113 | * an argument, i.e., "-pN" is NOT valid, only "-p N"!
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114 | * Indeed, util-linux-2.13-pre7 uses:
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115 | * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
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116 |
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117 | opt_complementary = "-1"; /* at least 1 arg */
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118 | opt_p = getopt32(argv, "+p");
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119 | argv += optind;
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120 |
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121 | if (opt_p) {
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122 | pid_str = *argv++;
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123 | if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
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124 | aff = pid_str;
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125 | pid_str = *argv; /* NB: *argv != NULL in this case */
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126 | }
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127 | /* else it was just "-p <pid>", and *argv == NULL */
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128 | pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
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129 | } else {
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130 | aff = *argv++; /* <aff> <cmd...> */
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131 | if (!*argv)
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132 | bb_show_usage();
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133 | }
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134 |
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135 | current_new = "current\0new";
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136 | if (opt_p) {
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137 | print_aff:
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138 | if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
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139 | bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
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140 | printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
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141 | pid, current_new, from_cpuset(&mask));
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142 | if (!*argv) {
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143 | /* Either it was just "-p <pid>",
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144 | * or it was "-p <aff> <pid>" and we came here
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145 | * for the second time (see goto below) */
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146 | return EXIT_SUCCESS;
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147 | }
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148 | *argv = NULL;
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149 | current_new += 8; /* "new" */
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150 | }
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151 |
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152 | /* Affinity was specified, translate it into cpu_set_t */
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153 | CPU_ZERO(&mask);
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154 | if (!ENABLE_FEATURE_TASKSET_FANCY) {
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155 | unsigned i;
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156 | unsigned long long m;
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157 |
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158 | /* Do not allow zero mask: */
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159 | m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
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160 | i = 0;
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161 | do {
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162 | if (m & 1)
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163 | CPU_SET(i, &mask);
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164 | i++;
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165 | m >>= 1;
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166 | } while (m != 0);
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167 | } else {
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168 | unsigned i;
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169 | char *last_byte;
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170 | char *bin;
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171 | uint8_t bit_in_byte;
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172 |
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173 | /* Cheap way to get "long enough" buffer */
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174 | bin = xstrdup(aff);
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175 |
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176 | if (aff[0] != '0' || (aff[1]|0x20) != 'x') {
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177 | /* TODO: decimal/octal masks are still limited to 2^64 */
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178 | unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
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179 | bin += strlen(bin);
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180 | last_byte = bin - 1;
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181 | while (m) {
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182 | *--bin = m & 0xff;
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183 | m >>= 8;
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184 | }
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185 | } else {
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186 | /* aff is "0x.....", we accept very long masks in this form */
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187 | last_byte = hex2bin(bin, aff + 2, INT_MAX);
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188 | if (!last_byte) {
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189 | bad_aff:
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190 | bb_error_msg_and_die("bad affinity '%s'", aff);
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191 | }
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192 | last_byte--; /* now points to the last byte */
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193 | }
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194 |
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195 | i = 0;
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196 | bit_in_byte = 1;
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197 | while (last_byte >= bin) {
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198 | if (bit_in_byte & *last_byte) {
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199 | if (i >= CPU_SETSIZE)
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200 | goto bad_aff;
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201 | CPU_SET(i, &mask);
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202 | //bb_error_msg("bit %d set", i);
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203 | }
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204 | i++;
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205 | /* bit_in_byte is uint8_t! & 0xff is implied */
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206 | bit_in_byte = (bit_in_byte << 1);
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207 | if (!bit_in_byte) {
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208 | bit_in_byte = 1;
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209 | last_byte--;
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210 | }
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211 | }
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212 | }
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213 |
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214 | /* Set pid's or our own (pid==0) affinity */
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215 | if (sched_setaffinity(pid, sizeof(mask), &mask))
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216 | bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
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217 |
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218 | if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
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219 | goto print_aff; /* print new affinity and exit */
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220 |
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221 | BB_EXECVP_or_die(argv);
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222 | }
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