xref: /linux-6.15/include/linux/cpumask.h (revision 4f3db074)
1 #ifndef __LINUX_CPUMASK_H
2 #define __LINUX_CPUMASK_H
3 
4 /*
5  * Cpumasks provide a bitmap suitable for representing the
6  * set of CPU's in a system, one bit position per CPU number.  In general,
7  * only nr_cpu_ids (<= NR_CPUS) bits are valid.
8  */
9 #include <linux/kernel.h>
10 #include <linux/threads.h>
11 #include <linux/bitmap.h>
12 #include <linux/bug.h>
13 
14 /* Don't assign or return these: may not be this big! */
15 typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
16 
17 /**
18  * cpumask_bits - get the bits in a cpumask
19  * @maskp: the struct cpumask *
20  *
21  * You should only assume nr_cpu_ids bits of this mask are valid.  This is
22  * a macro so it's const-correct.
23  */
24 #define cpumask_bits(maskp) ((maskp)->bits)
25 
26 /**
27  * cpumask_pr_args - printf args to output a cpumask
28  * @maskp: cpumask to be printed
29  *
30  * Can be used to provide arguments for '%*pb[l]' when printing a cpumask.
31  */
32 #define cpumask_pr_args(maskp)		nr_cpu_ids, cpumask_bits(maskp)
33 
34 #if NR_CPUS == 1
35 #define nr_cpu_ids		1
36 #else
37 extern int nr_cpu_ids;
38 #endif
39 
40 #ifdef CONFIG_CPUMASK_OFFSTACK
41 /* Assuming NR_CPUS is huge, a runtime limit is more efficient.  Also,
42  * not all bits may be allocated. */
43 #define nr_cpumask_bits	nr_cpu_ids
44 #else
45 #define nr_cpumask_bits	NR_CPUS
46 #endif
47 
48 /*
49  * The following particular system cpumasks and operations manage
50  * possible, present, active and online cpus.
51  *
52  *     cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
53  *     cpu_present_mask - has bit 'cpu' set iff cpu is populated
54  *     cpu_online_mask  - has bit 'cpu' set iff cpu available to scheduler
55  *     cpu_active_mask  - has bit 'cpu' set iff cpu available to migration
56  *
57  *  If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
58  *
59  *  The cpu_possible_mask is fixed at boot time, as the set of CPU id's
60  *  that it is possible might ever be plugged in at anytime during the
61  *  life of that system boot.  The cpu_present_mask is dynamic(*),
62  *  representing which CPUs are currently plugged in.  And
63  *  cpu_online_mask is the dynamic subset of cpu_present_mask,
64  *  indicating those CPUs available for scheduling.
65  *
66  *  If HOTPLUG is enabled, then cpu_possible_mask is forced to have
67  *  all NR_CPUS bits set, otherwise it is just the set of CPUs that
68  *  ACPI reports present at boot.
69  *
70  *  If HOTPLUG is enabled, then cpu_present_mask varies dynamically,
71  *  depending on what ACPI reports as currently plugged in, otherwise
72  *  cpu_present_mask is just a copy of cpu_possible_mask.
73  *
74  *  (*) Well, cpu_present_mask is dynamic in the hotplug case.  If not
75  *      hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
76  *
77  * Subtleties:
78  * 1) UP arch's (NR_CPUS == 1, CONFIG_SMP not defined) hardcode
79  *    assumption that their single CPU is online.  The UP
80  *    cpu_{online,possible,present}_masks are placebos.  Changing them
81  *    will have no useful affect on the following num_*_cpus()
82  *    and cpu_*() macros in the UP case.  This ugliness is a UP
83  *    optimization - don't waste any instructions or memory references
84  *    asking if you're online or how many CPUs there are if there is
85  *    only one CPU.
86  */
87 
88 extern const struct cpumask *const cpu_possible_mask;
89 extern const struct cpumask *const cpu_online_mask;
90 extern const struct cpumask *const cpu_present_mask;
91 extern const struct cpumask *const cpu_active_mask;
92 
93 #if NR_CPUS > 1
94 #define num_online_cpus()	cpumask_weight(cpu_online_mask)
95 #define num_possible_cpus()	cpumask_weight(cpu_possible_mask)
96 #define num_present_cpus()	cpumask_weight(cpu_present_mask)
97 #define num_active_cpus()	cpumask_weight(cpu_active_mask)
98 #define cpu_online(cpu)		cpumask_test_cpu((cpu), cpu_online_mask)
99 #define cpu_possible(cpu)	cpumask_test_cpu((cpu), cpu_possible_mask)
100 #define cpu_present(cpu)	cpumask_test_cpu((cpu), cpu_present_mask)
101 #define cpu_active(cpu)		cpumask_test_cpu((cpu), cpu_active_mask)
102 #else
103 #define num_online_cpus()	1U
104 #define num_possible_cpus()	1U
105 #define num_present_cpus()	1U
106 #define num_active_cpus()	1U
107 #define cpu_online(cpu)		((cpu) == 0)
108 #define cpu_possible(cpu)	((cpu) == 0)
109 #define cpu_present(cpu)	((cpu) == 0)
110 #define cpu_active(cpu)		((cpu) == 0)
111 #endif
112 
113 /* verify cpu argument to cpumask_* operators */
114 static inline unsigned int cpumask_check(unsigned int cpu)
115 {
116 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
117 	WARN_ON_ONCE(cpu >= nr_cpumask_bits);
118 #endif /* CONFIG_DEBUG_PER_CPU_MAPS */
119 	return cpu;
120 }
121 
122 #if NR_CPUS == 1
123 /* Uniprocessor.  Assume all masks are "1". */
124 static inline unsigned int cpumask_first(const struct cpumask *srcp)
125 {
126 	return 0;
127 }
128 
129 /* Valid inputs for n are -1 and 0. */
130 static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
131 {
132 	return n+1;
133 }
134 
135 static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
136 {
137 	return n+1;
138 }
139 
140 static inline unsigned int cpumask_next_and(int n,
141 					    const struct cpumask *srcp,
142 					    const struct cpumask *andp)
143 {
144 	return n+1;
145 }
146 
147 /* cpu must be a valid cpu, ie 0, so there's no other choice. */
148 static inline unsigned int cpumask_any_but(const struct cpumask *mask,
149 					   unsigned int cpu)
150 {
151 	return 1;
152 }
153 
154 static inline int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
155 {
156 	set_bit(0, cpumask_bits(dstp));
157 
158 	return 0;
159 }
160 
161 #define for_each_cpu(cpu, mask)			\
162 	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
163 #define for_each_cpu_not(cpu, mask)		\
164 	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
165 #define for_each_cpu_and(cpu, mask, and)	\
166 	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)and)
167 #else
168 /**
169  * cpumask_first - get the first cpu in a cpumask
170  * @srcp: the cpumask pointer
171  *
172  * Returns >= nr_cpu_ids if no cpus set.
173  */
174 static inline unsigned int cpumask_first(const struct cpumask *srcp)
175 {
176 	return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits);
177 }
178 
179 /**
180  * cpumask_next - get the next cpu in a cpumask
181  * @n: the cpu prior to the place to search (ie. return will be > @n)
182  * @srcp: the cpumask pointer
183  *
184  * Returns >= nr_cpu_ids if no further cpus set.
185  */
186 static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
187 {
188 	/* -1 is a legal arg here. */
189 	if (n != -1)
190 		cpumask_check(n);
191 	return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
192 }
193 
194 /**
195  * cpumask_next_zero - get the next unset cpu in a cpumask
196  * @n: the cpu prior to the place to search (ie. return will be > @n)
197  * @srcp: the cpumask pointer
198  *
199  * Returns >= nr_cpu_ids if no further cpus unset.
200  */
201 static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
202 {
203 	/* -1 is a legal arg here. */
204 	if (n != -1)
205 		cpumask_check(n);
206 	return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
207 }
208 
209 int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
210 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
211 int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp);
212 
213 /**
214  * for_each_cpu - iterate over every cpu in a mask
215  * @cpu: the (optionally unsigned) integer iterator
216  * @mask: the cpumask pointer
217  *
218  * After the loop, cpu is >= nr_cpu_ids.
219  */
220 #define for_each_cpu(cpu, mask)				\
221 	for ((cpu) = -1;				\
222 		(cpu) = cpumask_next((cpu), (mask)),	\
223 		(cpu) < nr_cpu_ids;)
224 
225 /**
226  * for_each_cpu_not - iterate over every cpu in a complemented mask
227  * @cpu: the (optionally unsigned) integer iterator
228  * @mask: the cpumask pointer
229  *
230  * After the loop, cpu is >= nr_cpu_ids.
231  */
232 #define for_each_cpu_not(cpu, mask)				\
233 	for ((cpu) = -1;					\
234 		(cpu) = cpumask_next_zero((cpu), (mask)),	\
235 		(cpu) < nr_cpu_ids;)
236 
237 /**
238  * for_each_cpu_and - iterate over every cpu in both masks
239  * @cpu: the (optionally unsigned) integer iterator
240  * @mask: the first cpumask pointer
241  * @and: the second cpumask pointer
242  *
243  * This saves a temporary CPU mask in many places.  It is equivalent to:
244  *	struct cpumask tmp;
245  *	cpumask_and(&tmp, &mask, &and);
246  *	for_each_cpu(cpu, &tmp)
247  *		...
248  *
249  * After the loop, cpu is >= nr_cpu_ids.
250  */
251 #define for_each_cpu_and(cpu, mask, and)				\
252 	for ((cpu) = -1;						\
253 		(cpu) = cpumask_next_and((cpu), (mask), (and)),		\
254 		(cpu) < nr_cpu_ids;)
255 #endif /* SMP */
256 
257 #define CPU_BITS_NONE						\
258 {								\
259 	[0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL			\
260 }
261 
262 #define CPU_BITS_CPU0						\
263 {								\
264 	[0] =  1UL						\
265 }
266 
267 /**
268  * cpumask_set_cpu - set a cpu in a cpumask
269  * @cpu: cpu number (< nr_cpu_ids)
270  * @dstp: the cpumask pointer
271  */
272 static inline void cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
273 {
274 	set_bit(cpumask_check(cpu), cpumask_bits(dstp));
275 }
276 
277 /**
278  * cpumask_clear_cpu - clear a cpu in a cpumask
279  * @cpu: cpu number (< nr_cpu_ids)
280  * @dstp: the cpumask pointer
281  */
282 static inline void cpumask_clear_cpu(int cpu, struct cpumask *dstp)
283 {
284 	clear_bit(cpumask_check(cpu), cpumask_bits(dstp));
285 }
286 
287 /**
288  * cpumask_test_cpu - test for a cpu in a cpumask
289  * @cpu: cpu number (< nr_cpu_ids)
290  * @cpumask: the cpumask pointer
291  *
292  * Returns 1 if @cpu is set in @cpumask, else returns 0
293  */
294 static inline int cpumask_test_cpu(int cpu, const struct cpumask *cpumask)
295 {
296 	return test_bit(cpumask_check(cpu), cpumask_bits((cpumask)));
297 }
298 
299 /**
300  * cpumask_test_and_set_cpu - atomically test and set a cpu in a cpumask
301  * @cpu: cpu number (< nr_cpu_ids)
302  * @cpumask: the cpumask pointer
303  *
304  * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
305  *
306  * test_and_set_bit wrapper for cpumasks.
307  */
308 static inline int cpumask_test_and_set_cpu(int cpu, struct cpumask *cpumask)
309 {
310 	return test_and_set_bit(cpumask_check(cpu), cpumask_bits(cpumask));
311 }
312 
313 /**
314  * cpumask_test_and_clear_cpu - atomically test and clear a cpu in a cpumask
315  * @cpu: cpu number (< nr_cpu_ids)
316  * @cpumask: the cpumask pointer
317  *
318  * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
319  *
320  * test_and_clear_bit wrapper for cpumasks.
321  */
322 static inline int cpumask_test_and_clear_cpu(int cpu, struct cpumask *cpumask)
323 {
324 	return test_and_clear_bit(cpumask_check(cpu), cpumask_bits(cpumask));
325 }
326 
327 /**
328  * cpumask_setall - set all cpus (< nr_cpu_ids) in a cpumask
329  * @dstp: the cpumask pointer
330  */
331 static inline void cpumask_setall(struct cpumask *dstp)
332 {
333 	bitmap_fill(cpumask_bits(dstp), nr_cpumask_bits);
334 }
335 
336 /**
337  * cpumask_clear - clear all cpus (< nr_cpu_ids) in a cpumask
338  * @dstp: the cpumask pointer
339  */
340 static inline void cpumask_clear(struct cpumask *dstp)
341 {
342 	bitmap_zero(cpumask_bits(dstp), nr_cpumask_bits);
343 }
344 
345 /**
346  * cpumask_and - *dstp = *src1p & *src2p
347  * @dstp: the cpumask result
348  * @src1p: the first input
349  * @src2p: the second input
350  *
351  * If *@dstp is empty, returns 0, else returns 1
352  */
353 static inline int cpumask_and(struct cpumask *dstp,
354 			       const struct cpumask *src1p,
355 			       const struct cpumask *src2p)
356 {
357 	return bitmap_and(cpumask_bits(dstp), cpumask_bits(src1p),
358 				       cpumask_bits(src2p), nr_cpumask_bits);
359 }
360 
361 /**
362  * cpumask_or - *dstp = *src1p | *src2p
363  * @dstp: the cpumask result
364  * @src1p: the first input
365  * @src2p: the second input
366  */
367 static inline void cpumask_or(struct cpumask *dstp, const struct cpumask *src1p,
368 			      const struct cpumask *src2p)
369 {
370 	bitmap_or(cpumask_bits(dstp), cpumask_bits(src1p),
371 				      cpumask_bits(src2p), nr_cpumask_bits);
372 }
373 
374 /**
375  * cpumask_xor - *dstp = *src1p ^ *src2p
376  * @dstp: the cpumask result
377  * @src1p: the first input
378  * @src2p: the second input
379  */
380 static inline void cpumask_xor(struct cpumask *dstp,
381 			       const struct cpumask *src1p,
382 			       const struct cpumask *src2p)
383 {
384 	bitmap_xor(cpumask_bits(dstp), cpumask_bits(src1p),
385 				       cpumask_bits(src2p), nr_cpumask_bits);
386 }
387 
388 /**
389  * cpumask_andnot - *dstp = *src1p & ~*src2p
390  * @dstp: the cpumask result
391  * @src1p: the first input
392  * @src2p: the second input
393  *
394  * If *@dstp is empty, returns 0, else returns 1
395  */
396 static inline int cpumask_andnot(struct cpumask *dstp,
397 				  const struct cpumask *src1p,
398 				  const struct cpumask *src2p)
399 {
400 	return bitmap_andnot(cpumask_bits(dstp), cpumask_bits(src1p),
401 					  cpumask_bits(src2p), nr_cpumask_bits);
402 }
403 
404 /**
405  * cpumask_complement - *dstp = ~*srcp
406  * @dstp: the cpumask result
407  * @srcp: the input to invert
408  */
409 static inline void cpumask_complement(struct cpumask *dstp,
410 				      const struct cpumask *srcp)
411 {
412 	bitmap_complement(cpumask_bits(dstp), cpumask_bits(srcp),
413 					      nr_cpumask_bits);
414 }
415 
416 /**
417  * cpumask_equal - *src1p == *src2p
418  * @src1p: the first input
419  * @src2p: the second input
420  */
421 static inline bool cpumask_equal(const struct cpumask *src1p,
422 				const struct cpumask *src2p)
423 {
424 	return bitmap_equal(cpumask_bits(src1p), cpumask_bits(src2p),
425 						 nr_cpumask_bits);
426 }
427 
428 /**
429  * cpumask_intersects - (*src1p & *src2p) != 0
430  * @src1p: the first input
431  * @src2p: the second input
432  */
433 static inline bool cpumask_intersects(const struct cpumask *src1p,
434 				     const struct cpumask *src2p)
435 {
436 	return bitmap_intersects(cpumask_bits(src1p), cpumask_bits(src2p),
437 						      nr_cpumask_bits);
438 }
439 
440 /**
441  * cpumask_subset - (*src1p & ~*src2p) == 0
442  * @src1p: the first input
443  * @src2p: the second input
444  *
445  * Returns 1 if *@src1p is a subset of *@src2p, else returns 0
446  */
447 static inline int cpumask_subset(const struct cpumask *src1p,
448 				 const struct cpumask *src2p)
449 {
450 	return bitmap_subset(cpumask_bits(src1p), cpumask_bits(src2p),
451 						  nr_cpumask_bits);
452 }
453 
454 /**
455  * cpumask_empty - *srcp == 0
456  * @srcp: the cpumask to that all cpus < nr_cpu_ids are clear.
457  */
458 static inline bool cpumask_empty(const struct cpumask *srcp)
459 {
460 	return bitmap_empty(cpumask_bits(srcp), nr_cpumask_bits);
461 }
462 
463 /**
464  * cpumask_full - *srcp == 0xFFFFFFFF...
465  * @srcp: the cpumask to that all cpus < nr_cpu_ids are set.
466  */
467 static inline bool cpumask_full(const struct cpumask *srcp)
468 {
469 	return bitmap_full(cpumask_bits(srcp), nr_cpumask_bits);
470 }
471 
472 /**
473  * cpumask_weight - Count of bits in *srcp
474  * @srcp: the cpumask to count bits (< nr_cpu_ids) in.
475  */
476 static inline unsigned int cpumask_weight(const struct cpumask *srcp)
477 {
478 	return bitmap_weight(cpumask_bits(srcp), nr_cpumask_bits);
479 }
480 
481 /**
482  * cpumask_shift_right - *dstp = *srcp >> n
483  * @dstp: the cpumask result
484  * @srcp: the input to shift
485  * @n: the number of bits to shift by
486  */
487 static inline void cpumask_shift_right(struct cpumask *dstp,
488 				       const struct cpumask *srcp, int n)
489 {
490 	bitmap_shift_right(cpumask_bits(dstp), cpumask_bits(srcp), n,
491 					       nr_cpumask_bits);
492 }
493 
494 /**
495  * cpumask_shift_left - *dstp = *srcp << n
496  * @dstp: the cpumask result
497  * @srcp: the input to shift
498  * @n: the number of bits to shift by
499  */
500 static inline void cpumask_shift_left(struct cpumask *dstp,
501 				      const struct cpumask *srcp, int n)
502 {
503 	bitmap_shift_left(cpumask_bits(dstp), cpumask_bits(srcp), n,
504 					      nr_cpumask_bits);
505 }
506 
507 /**
508  * cpumask_copy - *dstp = *srcp
509  * @dstp: the result
510  * @srcp: the input cpumask
511  */
512 static inline void cpumask_copy(struct cpumask *dstp,
513 				const struct cpumask *srcp)
514 {
515 	bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), nr_cpumask_bits);
516 }
517 
518 /**
519  * cpumask_any - pick a "random" cpu from *srcp
520  * @srcp: the input cpumask
521  *
522  * Returns >= nr_cpu_ids if no cpus set.
523  */
524 #define cpumask_any(srcp) cpumask_first(srcp)
525 
526 /**
527  * cpumask_first_and - return the first cpu from *srcp1 & *srcp2
528  * @src1p: the first input
529  * @src2p: the second input
530  *
531  * Returns >= nr_cpu_ids if no cpus set in both.  See also cpumask_next_and().
532  */
533 #define cpumask_first_and(src1p, src2p) cpumask_next_and(-1, (src1p), (src2p))
534 
535 /**
536  * cpumask_any_and - pick a "random" cpu from *mask1 & *mask2
537  * @mask1: the first input cpumask
538  * @mask2: the second input cpumask
539  *
540  * Returns >= nr_cpu_ids if no cpus set.
541  */
542 #define cpumask_any_and(mask1, mask2) cpumask_first_and((mask1), (mask2))
543 
544 /**
545  * cpumask_of - the cpumask containing just a given cpu
546  * @cpu: the cpu (<= nr_cpu_ids)
547  */
548 #define cpumask_of(cpu) (get_cpu_mask(cpu))
549 
550 /**
551  * cpumask_parse_user - extract a cpumask from a user string
552  * @buf: the buffer to extract from
553  * @len: the length of the buffer
554  * @dstp: the cpumask to set.
555  *
556  * Returns -errno, or 0 for success.
557  */
558 static inline int cpumask_parse_user(const char __user *buf, int len,
559 				     struct cpumask *dstp)
560 {
561 	return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpu_ids);
562 }
563 
564 /**
565  * cpumask_parselist_user - extract a cpumask from a user string
566  * @buf: the buffer to extract from
567  * @len: the length of the buffer
568  * @dstp: the cpumask to set.
569  *
570  * Returns -errno, or 0 for success.
571  */
572 static inline int cpumask_parselist_user(const char __user *buf, int len,
573 				     struct cpumask *dstp)
574 {
575 	return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
576 				     nr_cpu_ids);
577 }
578 
579 /**
580  * cpumask_parse - extract a cpumask from from a string
581  * @buf: the buffer to extract from
582  * @dstp: the cpumask to set.
583  *
584  * Returns -errno, or 0 for success.
585  */
586 static inline int cpumask_parse(const char *buf, struct cpumask *dstp)
587 {
588 	char *nl = strchr(buf, '\n');
589 	unsigned int len = nl ? (unsigned int)(nl - buf) : strlen(buf);
590 
591 	return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpu_ids);
592 }
593 
594 /**
595  * cpulist_parse - extract a cpumask from a user string of ranges
596  * @buf: the buffer to extract from
597  * @dstp: the cpumask to set.
598  *
599  * Returns -errno, or 0 for success.
600  */
601 static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
602 {
603 	return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpu_ids);
604 }
605 
606 /**
607  * cpumask_size - size to allocate for a 'struct cpumask' in bytes
608  *
609  * This will eventually be a runtime variable, depending on nr_cpu_ids.
610  */
611 static inline size_t cpumask_size(void)
612 {
613 	return BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long);
614 }
615 
616 /*
617  * cpumask_var_t: struct cpumask for stack usage.
618  *
619  * Oh, the wicked games we play!  In order to make kernel coding a
620  * little more difficult, we typedef cpumask_var_t to an array or a
621  * pointer: doing &mask on an array is a noop, so it still works.
622  *
623  * ie.
624  *	cpumask_var_t tmpmask;
625  *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
626  *		return -ENOMEM;
627  *
628  *	  ... use 'tmpmask' like a normal struct cpumask * ...
629  *
630  *	free_cpumask_var(tmpmask);
631  *
632  *
633  * However, one notable exception is there. alloc_cpumask_var() allocates
634  * only nr_cpumask_bits bits (in the other hand, real cpumask_t always has
635  * NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t.
636  *
637  *	cpumask_var_t tmpmask;
638  *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
639  *		return -ENOMEM;
640  *
641  *	var = *tmpmask;
642  *
643  * This code makes NR_CPUS length memcopy and brings to a memory corruption.
644  * cpumask_copy() provide safe copy functionality.
645  *
646  * Note that there is another evil here: If you define a cpumask_var_t
647  * as a percpu variable then the way to obtain the address of the cpumask
648  * structure differently influences what this_cpu_* operation needs to be
649  * used. Please use this_cpu_cpumask_var_t in those cases. The direct use
650  * of this_cpu_ptr() or this_cpu_read() will lead to failures when the
651  * other type of cpumask_var_t implementation is configured.
652  */
653 #ifdef CONFIG_CPUMASK_OFFSTACK
654 typedef struct cpumask *cpumask_var_t;
655 
656 #define this_cpu_cpumask_var_ptr(x) this_cpu_read(x)
657 
658 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
659 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
660 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
661 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
662 void alloc_bootmem_cpumask_var(cpumask_var_t *mask);
663 void free_cpumask_var(cpumask_var_t mask);
664 void free_bootmem_cpumask_var(cpumask_var_t mask);
665 
666 #else
667 typedef struct cpumask cpumask_var_t[1];
668 
669 #define this_cpu_cpumask_var_ptr(x) this_cpu_ptr(x)
670 
671 static inline bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
672 {
673 	return true;
674 }
675 
676 static inline bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
677 					  int node)
678 {
679 	return true;
680 }
681 
682 static inline bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
683 {
684 	cpumask_clear(*mask);
685 	return true;
686 }
687 
688 static inline bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
689 					  int node)
690 {
691 	cpumask_clear(*mask);
692 	return true;
693 }
694 
695 static inline void alloc_bootmem_cpumask_var(cpumask_var_t *mask)
696 {
697 }
698 
699 static inline void free_cpumask_var(cpumask_var_t mask)
700 {
701 }
702 
703 static inline void free_bootmem_cpumask_var(cpumask_var_t mask)
704 {
705 }
706 #endif /* CONFIG_CPUMASK_OFFSTACK */
707 
708 /* It's common to want to use cpu_all_mask in struct member initializers,
709  * so it has to refer to an address rather than a pointer. */
710 extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
711 #define cpu_all_mask to_cpumask(cpu_all_bits)
712 
713 /* First bits of cpu_bit_bitmap are in fact unset. */
714 #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
715 
716 #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
717 #define for_each_online_cpu(cpu)   for_each_cpu((cpu), cpu_online_mask)
718 #define for_each_present_cpu(cpu)  for_each_cpu((cpu), cpu_present_mask)
719 
720 /* Wrappers for arch boot code to manipulate normally-constant masks */
721 void set_cpu_possible(unsigned int cpu, bool possible);
722 void set_cpu_present(unsigned int cpu, bool present);
723 void set_cpu_online(unsigned int cpu, bool online);
724 void set_cpu_active(unsigned int cpu, bool active);
725 void init_cpu_present(const struct cpumask *src);
726 void init_cpu_possible(const struct cpumask *src);
727 void init_cpu_online(const struct cpumask *src);
728 
729 /**
730  * to_cpumask - convert an NR_CPUS bitmap to a struct cpumask *
731  * @bitmap: the bitmap
732  *
733  * There are a few places where cpumask_var_t isn't appropriate and
734  * static cpumasks must be used (eg. very early boot), yet we don't
735  * expose the definition of 'struct cpumask'.
736  *
737  * This does the conversion, and can be used as a constant initializer.
738  */
739 #define to_cpumask(bitmap)						\
740 	((struct cpumask *)(1 ? (bitmap)				\
741 			    : (void *)sizeof(__check_is_bitmap(bitmap))))
742 
743 static inline int __check_is_bitmap(const unsigned long *bitmap)
744 {
745 	return 1;
746 }
747 
748 /*
749  * Special-case data structure for "single bit set only" constant CPU masks.
750  *
751  * We pre-generate all the 64 (or 32) possible bit positions, with enough
752  * padding to the left and the right, and return the constant pointer
753  * appropriately offset.
754  */
755 extern const unsigned long
756 	cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)];
757 
758 static inline const struct cpumask *get_cpu_mask(unsigned int cpu)
759 {
760 	const unsigned long *p = cpu_bit_bitmap[1 + cpu % BITS_PER_LONG];
761 	p -= cpu / BITS_PER_LONG;
762 	return to_cpumask(p);
763 }
764 
765 #define cpu_is_offline(cpu)	unlikely(!cpu_online(cpu))
766 
767 #if NR_CPUS <= BITS_PER_LONG
768 #define CPU_BITS_ALL						\
769 {								\
770 	[BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)	\
771 }
772 
773 #else /* NR_CPUS > BITS_PER_LONG */
774 
775 #define CPU_BITS_ALL						\
776 {								\
777 	[0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,		\
778 	[BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)	\
779 }
780 #endif /* NR_CPUS > BITS_PER_LONG */
781 
782 /**
783  * cpumap_print_to_pagebuf  - copies the cpumask into the buffer either
784  *	as comma-separated list of cpus or hex values of cpumask
785  * @list: indicates whether the cpumap must be list
786  * @mask: the cpumask to copy
787  * @buf: the buffer to copy into
788  *
789  * Returns the length of the (null-terminated) @buf string, zero if
790  * nothing is copied.
791  */
792 static inline ssize_t
793 cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask)
794 {
795 	return bitmap_print_to_pagebuf(list, buf, cpumask_bits(mask),
796 				      nr_cpu_ids);
797 }
798 
799 #if NR_CPUS <= BITS_PER_LONG
800 #define CPU_MASK_ALL							\
801 (cpumask_t) { {								\
802 	[BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)	\
803 } }
804 #else
805 #define CPU_MASK_ALL							\
806 (cpumask_t) { {								\
807 	[0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,			\
808 	[BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)	\
809 } }
810 #endif /* NR_CPUS > BITS_PER_LONG */
811 
812 #define CPU_MASK_NONE							\
813 (cpumask_t) { {								\
814 	[0 ... BITS_TO_LONGS(NR_CPUS)-1] =  0UL				\
815 } }
816 
817 #define CPU_MASK_CPU0							\
818 (cpumask_t) { {								\
819 	[0] =  1UL							\
820 } }
821 
822 #endif /* __LINUX_CPUMASK_H */
823