cpumask.h 19 KB

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  1. #ifndef __LINUX_CPUMASK_H
  2. #define __LINUX_CPUMASK_H
  3. /*
  4. * Cpumasks provide a bitmap suitable for representing the
  5. * set of CPU's in a system, one bit position per CPU number.
  6. *
  7. * See detailed comments in the file linux/bitmap.h describing the
  8. * data type on which these cpumasks are based.
  9. *
  10. * For details of cpumask_scnprintf() and cpumask_parse_user(),
  11. * see bitmap_scnprintf() and bitmap_parse_user() in lib/bitmap.c.
  12. * For details of cpulist_scnprintf() and cpulist_parse(), see
  13. * bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
  14. * For details of cpu_remap(), see bitmap_bitremap in lib/bitmap.c
  15. * For details of cpus_remap(), see bitmap_remap in lib/bitmap.c.
  16. * For details of cpus_onto(), see bitmap_onto in lib/bitmap.c.
  17. * For details of cpus_fold(), see bitmap_fold in lib/bitmap.c.
  18. *
  19. * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
  20. * Note: The alternate operations with the suffix "_nr" are used
  21. * to limit the range of the loop to nr_cpu_ids instead of
  22. * NR_CPUS when NR_CPUS > 64 for performance reasons.
  23. * If NR_CPUS is <= 64 then most assembler bitmask
  24. * operators execute faster with a constant range, so
  25. * the operator will continue to use NR_CPUS.
  26. *
  27. * Another consideration is that nr_cpu_ids is initialized
  28. * to NR_CPUS and isn't lowered until the possible cpus are
  29. * discovered (including any disabled cpus). So early uses
  30. * will span the entire range of NR_CPUS.
  31. * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
  32. *
  33. * The available cpumask operations are:
  34. *
  35. * void cpu_set(cpu, mask) turn on bit 'cpu' in mask
  36. * void cpu_clear(cpu, mask) turn off bit 'cpu' in mask
  37. * void cpus_setall(mask) set all bits
  38. * void cpus_clear(mask) clear all bits
  39. * int cpu_isset(cpu, mask) true iff bit 'cpu' set in mask
  40. * int cpu_test_and_set(cpu, mask) test and set bit 'cpu' in mask
  41. *
  42. * void cpus_and(dst, src1, src2) dst = src1 & src2 [intersection]
  43. * void cpus_or(dst, src1, src2) dst = src1 | src2 [union]
  44. * void cpus_xor(dst, src1, src2) dst = src1 ^ src2
  45. * void cpus_andnot(dst, src1, src2) dst = src1 & ~src2
  46. * void cpus_complement(dst, src) dst = ~src
  47. *
  48. * int cpus_equal(mask1, mask2) Does mask1 == mask2?
  49. * int cpus_intersects(mask1, mask2) Do mask1 and mask2 intersect?
  50. * int cpus_subset(mask1, mask2) Is mask1 a subset of mask2?
  51. * int cpus_empty(mask) Is mask empty (no bits sets)?
  52. * int cpus_full(mask) Is mask full (all bits sets)?
  53. * int cpus_weight(mask) Hamming weigh - number of set bits
  54. * int cpus_weight_nr(mask) Same using nr_cpu_ids instead of NR_CPUS
  55. *
  56. * void cpus_shift_right(dst, src, n) Shift right
  57. * void cpus_shift_left(dst, src, n) Shift left
  58. *
  59. * int first_cpu(mask) Number lowest set bit, or NR_CPUS
  60. * int next_cpu(cpu, mask) Next cpu past 'cpu', or NR_CPUS
  61. * int next_cpu_nr(cpu, mask) Next cpu past 'cpu', or nr_cpu_ids
  62. *
  63. * cpumask_t cpumask_of_cpu(cpu) Return cpumask with bit 'cpu' set
  64. *ifdef CONFIG_HAS_CPUMASK_OF_CPU
  65. * cpumask_of_cpu_ptr_declare(v) Declares cpumask_t *v
  66. * cpumask_of_cpu_ptr_next(v, cpu) Sets v = &cpumask_of_cpu_map[cpu]
  67. * cpumask_of_cpu_ptr(v, cpu) Combines above two operations
  68. *else
  69. * cpumask_of_cpu_ptr_declare(v) Declares cpumask_t _v and *v = &_v
  70. * cpumask_of_cpu_ptr_next(v, cpu) Sets _v = cpumask_of_cpu(cpu)
  71. * cpumask_of_cpu_ptr(v, cpu) Combines above two operations
  72. *endif
  73. * CPU_MASK_ALL Initializer - all bits set
  74. * CPU_MASK_NONE Initializer - no bits set
  75. * unsigned long *cpus_addr(mask) Array of unsigned long's in mask
  76. *
  77. * CPUMASK_ALLOC kmalloc's a structure that is a composite of many cpumask_t
  78. * variables, and CPUMASK_PTR provides pointers to each field.
  79. *
  80. * The structure should be defined something like this:
  81. * struct my_cpumasks {
  82. * cpumask_t mask1;
  83. * cpumask_t mask2;
  84. * };
  85. *
  86. * Usage is then:
  87. * CPUMASK_ALLOC(my_cpumasks);
  88. * CPUMASK_PTR(mask1, my_cpumasks);
  89. * CPUMASK_PTR(mask2, my_cpumasks);
  90. *
  91. * --- DO NOT reference cpumask_t pointers until this check ---
  92. * if (my_cpumasks == NULL)
  93. * "kmalloc failed"...
  94. *
  95. * References are now pointers to the cpumask_t variables (*mask1, ...)
  96. *
  97. *if NR_CPUS > BITS_PER_LONG
  98. * CPUMASK_ALLOC(m) Declares and allocates struct m *m =
  99. * kmalloc(sizeof(*m), GFP_KERNEL)
  100. * CPUMASK_FREE(m) Macro for kfree(m)
  101. *else
  102. * CPUMASK_ALLOC(m) Declares struct m _m, *m = &_m
  103. * CPUMASK_FREE(m) Nop
  104. *endif
  105. * CPUMASK_PTR(v, m) Declares cpumask_t *v = &(m->v)
  106. * ------------------------------------------------------------------------
  107. *
  108. * int cpumask_scnprintf(buf, len, mask) Format cpumask for printing
  109. * int cpumask_parse_user(ubuf, ulen, mask) Parse ascii string as cpumask
  110. * int cpulist_scnprintf(buf, len, mask) Format cpumask as list for printing
  111. * int cpulist_parse(buf, map) Parse ascii string as cpulist
  112. * int cpu_remap(oldbit, old, new) newbit = map(old, new)(oldbit)
  113. * void cpus_remap(dst, src, old, new) *dst = map(old, new)(src)
  114. * void cpus_onto(dst, orig, relmap) *dst = orig relative to relmap
  115. * void cpus_fold(dst, orig, sz) dst bits = orig bits mod sz
  116. *
  117. * for_each_cpu_mask(cpu, mask) for-loop cpu over mask using NR_CPUS
  118. * for_each_cpu_mask_nr(cpu, mask) for-loop cpu over mask using nr_cpu_ids
  119. *
  120. * int num_online_cpus() Number of online CPUs
  121. * int num_possible_cpus() Number of all possible CPUs
  122. * int num_present_cpus() Number of present CPUs
  123. *
  124. * int cpu_online(cpu) Is some cpu online?
  125. * int cpu_possible(cpu) Is some cpu possible?
  126. * int cpu_present(cpu) Is some cpu present (can schedule)?
  127. *
  128. * int any_online_cpu(mask) First online cpu in mask
  129. *
  130. * for_each_possible_cpu(cpu) for-loop cpu over cpu_possible_map
  131. * for_each_online_cpu(cpu) for-loop cpu over cpu_online_map
  132. * for_each_present_cpu(cpu) for-loop cpu over cpu_present_map
  133. *
  134. * Subtlety:
  135. * 1) The 'type-checked' form of cpu_isset() causes gcc (3.3.2, anyway)
  136. * to generate slightly worse code. Note for example the additional
  137. * 40 lines of assembly code compiling the "for each possible cpu"
  138. * loops buried in the disk_stat_read() macros calls when compiling
  139. * drivers/block/genhd.c (arch i386, CONFIG_SMP=y). So use a simple
  140. * one-line #define for cpu_isset(), instead of wrapping an inline
  141. * inside a macro, the way we do the other calls.
  142. */
  143. #include <linux/kernel.h>
  144. #include <linux/threads.h>
  145. #include <linux/bitmap.h>
  146. typedef struct { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
  147. extern cpumask_t _unused_cpumask_arg_;
  148. #define cpu_set(cpu, dst) __cpu_set((cpu), &(dst))
  149. static inline void __cpu_set(int cpu, volatile cpumask_t *dstp)
  150. {
  151. set_bit(cpu, dstp->bits);
  152. }
  153. #define cpu_clear(cpu, dst) __cpu_clear((cpu), &(dst))
  154. static inline void __cpu_clear(int cpu, volatile cpumask_t *dstp)
  155. {
  156. clear_bit(cpu, dstp->bits);
  157. }
  158. #define cpus_setall(dst) __cpus_setall(&(dst), NR_CPUS)
  159. static inline void __cpus_setall(cpumask_t *dstp, int nbits)
  160. {
  161. bitmap_fill(dstp->bits, nbits);
  162. }
  163. #define cpus_clear(dst) __cpus_clear(&(dst), NR_CPUS)
  164. static inline void __cpus_clear(cpumask_t *dstp, int nbits)
  165. {
  166. bitmap_zero(dstp->bits, nbits);
  167. }
  168. /* No static inline type checking - see Subtlety (1) above. */
  169. #define cpu_isset(cpu, cpumask) test_bit((cpu), (cpumask).bits)
  170. #define cpu_test_and_set(cpu, cpumask) __cpu_test_and_set((cpu), &(cpumask))
  171. static inline int __cpu_test_and_set(int cpu, cpumask_t *addr)
  172. {
  173. return test_and_set_bit(cpu, addr->bits);
  174. }
  175. #define cpus_and(dst, src1, src2) __cpus_and(&(dst), &(src1), &(src2), NR_CPUS)
  176. static inline void __cpus_and(cpumask_t *dstp, const cpumask_t *src1p,
  177. const cpumask_t *src2p, int nbits)
  178. {
  179. bitmap_and(dstp->bits, src1p->bits, src2p->bits, nbits);
  180. }
  181. #define cpus_or(dst, src1, src2) __cpus_or(&(dst), &(src1), &(src2), NR_CPUS)
  182. static inline void __cpus_or(cpumask_t *dstp, const cpumask_t *src1p,
  183. const cpumask_t *src2p, int nbits)
  184. {
  185. bitmap_or(dstp->bits, src1p->bits, src2p->bits, nbits);
  186. }
  187. #define cpus_xor(dst, src1, src2) __cpus_xor(&(dst), &(src1), &(src2), NR_CPUS)
  188. static inline void __cpus_xor(cpumask_t *dstp, const cpumask_t *src1p,
  189. const cpumask_t *src2p, int nbits)
  190. {
  191. bitmap_xor(dstp->bits, src1p->bits, src2p->bits, nbits);
  192. }
  193. #define cpus_andnot(dst, src1, src2) \
  194. __cpus_andnot(&(dst), &(src1), &(src2), NR_CPUS)
  195. static inline void __cpus_andnot(cpumask_t *dstp, const cpumask_t *src1p,
  196. const cpumask_t *src2p, int nbits)
  197. {
  198. bitmap_andnot(dstp->bits, src1p->bits, src2p->bits, nbits);
  199. }
  200. #define cpus_complement(dst, src) __cpus_complement(&(dst), &(src), NR_CPUS)
  201. static inline void __cpus_complement(cpumask_t *dstp,
  202. const cpumask_t *srcp, int nbits)
  203. {
  204. bitmap_complement(dstp->bits, srcp->bits, nbits);
  205. }
  206. #define cpus_equal(src1, src2) __cpus_equal(&(src1), &(src2), NR_CPUS)
  207. static inline int __cpus_equal(const cpumask_t *src1p,
  208. const cpumask_t *src2p, int nbits)
  209. {
  210. return bitmap_equal(src1p->bits, src2p->bits, nbits);
  211. }
  212. #define cpus_intersects(src1, src2) __cpus_intersects(&(src1), &(src2), NR_CPUS)
  213. static inline int __cpus_intersects(const cpumask_t *src1p,
  214. const cpumask_t *src2p, int nbits)
  215. {
  216. return bitmap_intersects(src1p->bits, src2p->bits, nbits);
  217. }
  218. #define cpus_subset(src1, src2) __cpus_subset(&(src1), &(src2), NR_CPUS)
  219. static inline int __cpus_subset(const cpumask_t *src1p,
  220. const cpumask_t *src2p, int nbits)
  221. {
  222. return bitmap_subset(src1p->bits, src2p->bits, nbits);
  223. }
  224. #define cpus_empty(src) __cpus_empty(&(src), NR_CPUS)
  225. static inline int __cpus_empty(const cpumask_t *srcp, int nbits)
  226. {
  227. return bitmap_empty(srcp->bits, nbits);
  228. }
  229. #define cpus_full(cpumask) __cpus_full(&(cpumask), NR_CPUS)
  230. static inline int __cpus_full(const cpumask_t *srcp, int nbits)
  231. {
  232. return bitmap_full(srcp->bits, nbits);
  233. }
  234. #define cpus_weight(cpumask) __cpus_weight(&(cpumask), NR_CPUS)
  235. static inline int __cpus_weight(const cpumask_t *srcp, int nbits)
  236. {
  237. return bitmap_weight(srcp->bits, nbits);
  238. }
  239. #define cpus_shift_right(dst, src, n) \
  240. __cpus_shift_right(&(dst), &(src), (n), NR_CPUS)
  241. static inline void __cpus_shift_right(cpumask_t *dstp,
  242. const cpumask_t *srcp, int n, int nbits)
  243. {
  244. bitmap_shift_right(dstp->bits, srcp->bits, n, nbits);
  245. }
  246. #define cpus_shift_left(dst, src, n) \
  247. __cpus_shift_left(&(dst), &(src), (n), NR_CPUS)
  248. static inline void __cpus_shift_left(cpumask_t *dstp,
  249. const cpumask_t *srcp, int n, int nbits)
  250. {
  251. bitmap_shift_left(dstp->bits, srcp->bits, n, nbits);
  252. }
  253. #ifdef CONFIG_HAVE_CPUMASK_OF_CPU_MAP
  254. extern cpumask_t *cpumask_of_cpu_map;
  255. #define cpumask_of_cpu(cpu) (cpumask_of_cpu_map[cpu])
  256. #define cpumask_of_cpu_ptr(v, cpu) \
  257. const cpumask_t *v = &cpumask_of_cpu(cpu)
  258. #define cpumask_of_cpu_ptr_declare(v) \
  259. const cpumask_t *v
  260. #define cpumask_of_cpu_ptr_next(v, cpu) \
  261. v = &cpumask_of_cpu(cpu)
  262. #else
  263. #define cpumask_of_cpu(cpu) \
  264. ({ \
  265. typeof(_unused_cpumask_arg_) m; \
  266. if (sizeof(m) == sizeof(unsigned long)) { \
  267. m.bits[0] = 1UL<<(cpu); \
  268. } else { \
  269. cpus_clear(m); \
  270. cpu_set((cpu), m); \
  271. } \
  272. m; \
  273. })
  274. #define cpumask_of_cpu_ptr(v, cpu) \
  275. cpumask_t _##v = cpumask_of_cpu(cpu); \
  276. const cpumask_t *v = &_##v
  277. #define cpumask_of_cpu_ptr_declare(v) \
  278. cpumask_t _##v; \
  279. const cpumask_t *v = &_##v
  280. #define cpumask_of_cpu_ptr_next(v, cpu) \
  281. _##v = cpumask_of_cpu(cpu)
  282. #endif
  283. #define CPU_MASK_LAST_WORD BITMAP_LAST_WORD_MASK(NR_CPUS)
  284. #if NR_CPUS <= BITS_PER_LONG
  285. #define CPU_MASK_ALL \
  286. (cpumask_t) { { \
  287. [BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD \
  288. } }
  289. #define CPU_MASK_ALL_PTR (&CPU_MASK_ALL)
  290. #else
  291. #define CPU_MASK_ALL \
  292. (cpumask_t) { { \
  293. [0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL, \
  294. [BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD \
  295. } }
  296. /* cpu_mask_all is in init/main.c */
  297. extern cpumask_t cpu_mask_all;
  298. #define CPU_MASK_ALL_PTR (&cpu_mask_all)
  299. #endif
  300. #define CPU_MASK_NONE \
  301. (cpumask_t) { { \
  302. [0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL \
  303. } }
  304. #define CPU_MASK_CPU0 \
  305. (cpumask_t) { { \
  306. [0] = 1UL \
  307. } }
  308. #define cpus_addr(src) ((src).bits)
  309. #if NR_CPUS > BITS_PER_LONG
  310. #define CPUMASK_ALLOC(m) struct m *m = kmalloc(sizeof(*m), GFP_KERNEL)
  311. #define CPUMASK_FREE(m) kfree(m)
  312. #else
  313. #define CPUMASK_ALLOC(m) struct m _m, *m = &_m
  314. #define CPUMASK_FREE(m)
  315. #endif
  316. #define CPUMASK_PTR(v, m) cpumask_t *v = &(m->v)
  317. #define cpumask_scnprintf(buf, len, src) \
  318. __cpumask_scnprintf((buf), (len), &(src), NR_CPUS)
  319. static inline int __cpumask_scnprintf(char *buf, int len,
  320. const cpumask_t *srcp, int nbits)
  321. {
  322. return bitmap_scnprintf(buf, len, srcp->bits, nbits);
  323. }
  324. #define cpumask_parse_user(ubuf, ulen, dst) \
  325. __cpumask_parse_user((ubuf), (ulen), &(dst), NR_CPUS)
  326. static inline int __cpumask_parse_user(const char __user *buf, int len,
  327. cpumask_t *dstp, int nbits)
  328. {
  329. return bitmap_parse_user(buf, len, dstp->bits, nbits);
  330. }
  331. #define cpulist_scnprintf(buf, len, src) \
  332. __cpulist_scnprintf((buf), (len), &(src), NR_CPUS)
  333. static inline int __cpulist_scnprintf(char *buf, int len,
  334. const cpumask_t *srcp, int nbits)
  335. {
  336. return bitmap_scnlistprintf(buf, len, srcp->bits, nbits);
  337. }
  338. #define cpulist_parse(buf, dst) __cpulist_parse((buf), &(dst), NR_CPUS)
  339. static inline int __cpulist_parse(const char *buf, cpumask_t *dstp, int nbits)
  340. {
  341. return bitmap_parselist(buf, dstp->bits, nbits);
  342. }
  343. #define cpu_remap(oldbit, old, new) \
  344. __cpu_remap((oldbit), &(old), &(new), NR_CPUS)
  345. static inline int __cpu_remap(int oldbit,
  346. const cpumask_t *oldp, const cpumask_t *newp, int nbits)
  347. {
  348. return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nbits);
  349. }
  350. #define cpus_remap(dst, src, old, new) \
  351. __cpus_remap(&(dst), &(src), &(old), &(new), NR_CPUS)
  352. static inline void __cpus_remap(cpumask_t *dstp, const cpumask_t *srcp,
  353. const cpumask_t *oldp, const cpumask_t *newp, int nbits)
  354. {
  355. bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, nbits);
  356. }
  357. #define cpus_onto(dst, orig, relmap) \
  358. __cpus_onto(&(dst), &(orig), &(relmap), NR_CPUS)
  359. static inline void __cpus_onto(cpumask_t *dstp, const cpumask_t *origp,
  360. const cpumask_t *relmapp, int nbits)
  361. {
  362. bitmap_onto(dstp->bits, origp->bits, relmapp->bits, nbits);
  363. }
  364. #define cpus_fold(dst, orig, sz) \
  365. __cpus_fold(&(dst), &(orig), sz, NR_CPUS)
  366. static inline void __cpus_fold(cpumask_t *dstp, const cpumask_t *origp,
  367. int sz, int nbits)
  368. {
  369. bitmap_fold(dstp->bits, origp->bits, sz, nbits);
  370. }
  371. #if NR_CPUS == 1
  372. #define nr_cpu_ids 1
  373. #define first_cpu(src) ({ (void)(src); 0; })
  374. #define next_cpu(n, src) ({ (void)(src); 1; })
  375. #define any_online_cpu(mask) 0
  376. #define for_each_cpu_mask(cpu, mask) \
  377. for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
  378. #else /* NR_CPUS > 1 */
  379. extern int nr_cpu_ids;
  380. int __first_cpu(const cpumask_t *srcp);
  381. int __next_cpu(int n, const cpumask_t *srcp);
  382. int __any_online_cpu(const cpumask_t *mask);
  383. #define first_cpu(src) __first_cpu(&(src))
  384. #define next_cpu(n, src) __next_cpu((n), &(src))
  385. #define any_online_cpu(mask) __any_online_cpu(&(mask))
  386. #define for_each_cpu_mask(cpu, mask) \
  387. for ((cpu) = -1; \
  388. (cpu) = next_cpu((cpu), (mask)), \
  389. (cpu) < NR_CPUS; )
  390. #endif
  391. #if NR_CPUS <= 64
  392. #define next_cpu_nr(n, src) next_cpu(n, src)
  393. #define cpus_weight_nr(cpumask) cpus_weight(cpumask)
  394. #define for_each_cpu_mask_nr(cpu, mask) for_each_cpu_mask(cpu, mask)
  395. #else /* NR_CPUS > 64 */
  396. int __next_cpu_nr(int n, const cpumask_t *srcp);
  397. #define next_cpu_nr(n, src) __next_cpu_nr((n), &(src))
  398. #define cpus_weight_nr(cpumask) __cpus_weight(&(cpumask), nr_cpu_ids)
  399. #define for_each_cpu_mask_nr(cpu, mask) \
  400. for ((cpu) = -1; \
  401. (cpu) = next_cpu_nr((cpu), (mask)), \
  402. (cpu) < nr_cpu_ids; )
  403. #endif /* NR_CPUS > 64 */
  404. /*
  405. * The following particular system cpumasks and operations manage
  406. * possible, present and online cpus. Each of them is a fixed size
  407. * bitmap of size NR_CPUS.
  408. *
  409. * #ifdef CONFIG_HOTPLUG_CPU
  410. * cpu_possible_map - has bit 'cpu' set iff cpu is populatable
  411. * cpu_present_map - has bit 'cpu' set iff cpu is populated
  412. * cpu_online_map - has bit 'cpu' set iff cpu available to scheduler
  413. * #else
  414. * cpu_possible_map - has bit 'cpu' set iff cpu is populated
  415. * cpu_present_map - copy of cpu_possible_map
  416. * cpu_online_map - has bit 'cpu' set iff cpu available to scheduler
  417. * #endif
  418. *
  419. * In either case, NR_CPUS is fixed at compile time, as the static
  420. * size of these bitmaps. The cpu_possible_map is fixed at boot
  421. * time, as the set of CPU id's that it is possible might ever
  422. * be plugged in at anytime during the life of that system boot.
  423. * The cpu_present_map is dynamic(*), representing which CPUs
  424. * are currently plugged in. And cpu_online_map is the dynamic
  425. * subset of cpu_present_map, indicating those CPUs available
  426. * for scheduling.
  427. *
  428. * If HOTPLUG is enabled, then cpu_possible_map is forced to have
  429. * all NR_CPUS bits set, otherwise it is just the set of CPUs that
  430. * ACPI reports present at boot.
  431. *
  432. * If HOTPLUG is enabled, then cpu_present_map varies dynamically,
  433. * depending on what ACPI reports as currently plugged in, otherwise
  434. * cpu_present_map is just a copy of cpu_possible_map.
  435. *
  436. * (*) Well, cpu_present_map is dynamic in the hotplug case. If not
  437. * hotplug, it's a copy of cpu_possible_map, hence fixed at boot.
  438. *
  439. * Subtleties:
  440. * 1) UP arch's (NR_CPUS == 1, CONFIG_SMP not defined) hardcode
  441. * assumption that their single CPU is online. The UP
  442. * cpu_{online,possible,present}_maps are placebos. Changing them
  443. * will have no useful affect on the following num_*_cpus()
  444. * and cpu_*() macros in the UP case. This ugliness is a UP
  445. * optimization - don't waste any instructions or memory references
  446. * asking if you're online or how many CPUs there are if there is
  447. * only one CPU.
  448. * 2) Most SMP arch's #define some of these maps to be some
  449. * other map specific to that arch. Therefore, the following
  450. * must be #define macros, not inlines. To see why, examine
  451. * the assembly code produced by the following. Note that
  452. * set1() writes phys_x_map, but set2() writes x_map:
  453. * int x_map, phys_x_map;
  454. * #define set1(a) x_map = a
  455. * inline void set2(int a) { x_map = a; }
  456. * #define x_map phys_x_map
  457. * main(){ set1(3); set2(5); }
  458. */
  459. extern cpumask_t cpu_possible_map;
  460. extern cpumask_t cpu_online_map;
  461. extern cpumask_t cpu_present_map;
  462. #if NR_CPUS > 1
  463. #define num_online_cpus() cpus_weight_nr(cpu_online_map)
  464. #define num_possible_cpus() cpus_weight_nr(cpu_possible_map)
  465. #define num_present_cpus() cpus_weight_nr(cpu_present_map)
  466. #define cpu_online(cpu) cpu_isset((cpu), cpu_online_map)
  467. #define cpu_possible(cpu) cpu_isset((cpu), cpu_possible_map)
  468. #define cpu_present(cpu) cpu_isset((cpu), cpu_present_map)
  469. #else
  470. #define num_online_cpus() 1
  471. #define num_possible_cpus() 1
  472. #define num_present_cpus() 1
  473. #define cpu_online(cpu) ((cpu) == 0)
  474. #define cpu_possible(cpu) ((cpu) == 0)
  475. #define cpu_present(cpu) ((cpu) == 0)
  476. #endif
  477. #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
  478. #define for_each_possible_cpu(cpu) for_each_cpu_mask_nr((cpu), cpu_possible_map)
  479. #define for_each_online_cpu(cpu) for_each_cpu_mask_nr((cpu), cpu_online_map)
  480. #define for_each_present_cpu(cpu) for_each_cpu_mask_nr((cpu), cpu_present_map)
  481. #endif /* __LINUX_CPUMASK_H */