xref: /linux-6.15/include/linux/cpumask.h (revision 6faeeea4)
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 typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
15 
16 /**
17  * cpumask_bits - get the bits in a cpumask
18  * @maskp: the struct cpumask *
19  *
20  * You should only assume nr_cpu_ids bits of this mask are valid.  This is
21  * a macro so it's const-correct.
22  */
23 #define cpumask_bits(maskp) ((maskp)->bits)
24 
25 /**
26  * cpumask_pr_args - printf args to output a cpumask
27  * @maskp: cpumask to be printed
28  *
29  * Can be used to provide arguments for '%*pb[l]' when printing a cpumask.
30  */
31 #define cpumask_pr_args(maskp)		nr_cpu_ids, cpumask_bits(maskp)
32 
33 #if NR_CPUS == 1
34 #define nr_cpu_ids		1
35 #else
36 extern int nr_cpu_ids;
37 #endif
38 
39 #ifdef CONFIG_CPUMASK_OFFSTACK
40 /* Assuming NR_CPUS is huge, a runtime limit is more efficient.  Also,
41  * not all bits may be allocated. */
42 #define nr_cpumask_bits	nr_cpu_ids
43 #else
44 #define nr_cpumask_bits	NR_CPUS
45 #endif
46 
47 /*
48  * The following particular system cpumasks and operations manage
49  * possible, present, active and online cpus.
50  *
51  *     cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
52  *     cpu_present_mask - has bit 'cpu' set iff cpu is populated
53  *     cpu_online_mask  - has bit 'cpu' set iff cpu available to scheduler
54  *     cpu_active_mask  - has bit 'cpu' set iff cpu available to migration
55  *
56  *  If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
57  *
58  *  The cpu_possible_mask is fixed at boot time, as the set of CPU id's
59  *  that it is possible might ever be plugged in at anytime during the
60  *  life of that system boot.  The cpu_present_mask is dynamic(*),
61  *  representing which CPUs are currently plugged in.  And
62  *  cpu_online_mask is the dynamic subset of cpu_present_mask,
63  *  indicating those CPUs available for scheduling.
64  *
65  *  If HOTPLUG is enabled, then cpu_possible_mask is forced to have
66  *  all NR_CPUS bits set, otherwise it is just the set of CPUs that
67  *  ACPI reports present at boot.
68  *
69  *  If HOTPLUG is enabled, then cpu_present_mask varies dynamically,
70  *  depending on what ACPI reports as currently plugged in, otherwise
71  *  cpu_present_mask is just a copy of cpu_possible_mask.
72  *
73  *  (*) Well, cpu_present_mask is dynamic in the hotplug case.  If not
74  *      hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
75  *
76  * Subtleties:
77  * 1) UP arch's (NR_CPUS == 1, CONFIG_SMP not defined) hardcode
78  *    assumption that their single CPU is online.  The UP
79  *    cpu_{online,possible,present}_masks are placebos.  Changing them
80  *    will have no useful affect on the following num_*_cpus()
81  *    and cpu_*() macros in the UP case.  This ugliness is a UP
82  *    optimization - don't waste any instructions or memory references
83  *    asking if you're online or how many CPUs there are if there is
84  *    only one CPU.
85  */
86 
87 extern const struct cpumask *const cpu_possible_mask;
88 extern const struct cpumask *const cpu_online_mask;
89 extern const struct cpumask *const cpu_present_mask;
90 extern const struct cpumask *const cpu_active_mask;
91 
92 #if NR_CPUS > 1
93 #define num_online_cpus()	cpumask_weight(cpu_online_mask)
94 #define num_possible_cpus()	cpumask_weight(cpu_possible_mask)
95 #define num_present_cpus()	cpumask_weight(cpu_present_mask)
96 #define num_active_cpus()	cpumask_weight(cpu_active_mask)
97 #define cpu_online(cpu)		cpumask_test_cpu((cpu), cpu_online_mask)
98 #define cpu_possible(cpu)	cpumask_test_cpu((cpu), cpu_possible_mask)
99 #define cpu_present(cpu)	cpumask_test_cpu((cpu), cpu_present_mask)
100 #define cpu_active(cpu)		cpumask_test_cpu((cpu), cpu_active_mask)
101 #else
102 #define num_online_cpus()	1U
103 #define num_possible_cpus()	1U
104 #define num_present_cpus()	1U
105 #define num_active_cpus()	1U
106 #define cpu_online(cpu)		((cpu) == 0)
107 #define cpu_possible(cpu)	((cpu) == 0)
108 #define cpu_present(cpu)	((cpu) == 0)
109 #define cpu_active(cpu)		((cpu) == 0)
110 #endif
111 
112 /* verify cpu argument to cpumask_* operators */
113 static inline unsigned int cpumask_check(unsigned int cpu)
114 {
115 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
116 	WARN_ON_ONCE(cpu >= nr_cpumask_bits);
117 #endif /* CONFIG_DEBUG_PER_CPU_MAPS */
118 	return cpu;
119 }
120 
121 #if NR_CPUS == 1
122 /* Uniprocessor.  Assume all masks are "1". */
123 static inline unsigned int cpumask_first(const struct cpumask *srcp)
124 {
125 	return 0;
126 }
127 
128 /* Valid inputs for n are -1 and 0. */
129 static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
130 {
131 	return n+1;
132 }
133 
134 static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
135 {
136 	return n+1;
137 }
138 
139 static inline unsigned int cpumask_next_and(int n,
140 					    const struct cpumask *srcp,
141 					    const struct cpumask *andp)
142 {
143 	return n+1;
144 }
145 
146 /* cpu must be a valid cpu, ie 0, so there's no other choice. */
147 static inline unsigned int cpumask_any_but(const struct cpumask *mask,
148 					   unsigned int cpu)
149 {
150 	return 1;
151 }
152 
153 static inline int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
154 {
155 	set_bit(0, cpumask_bits(dstp));
156 
157 	return 0;
158 }
159 
160 #define for_each_cpu(cpu, mask)			\
161 	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
162 #define for_each_cpu_not(cpu, mask)		\
163 	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
164 #define for_each_cpu_and(cpu, mask, and)	\
165 	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)and)
166 #else
167 /**
168  * cpumask_first - get the first cpu in a cpumask
169  * @srcp: the cpumask pointer
170  *
171  * Returns >= nr_cpu_ids if no cpus set.
172  */
173 static inline unsigned int cpumask_first(const struct cpumask *srcp)
174 {
175 	return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits);
176 }
177 
178 /**
179  * cpumask_next - get the next cpu in a cpumask
180  * @n: the cpu prior to the place to search (ie. return will be > @n)
181  * @srcp: the cpumask pointer
182  *
183  * Returns >= nr_cpu_ids if no further cpus set.
184  */
185 static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
186 {
187 	/* -1 is a legal arg here. */
188 	if (n != -1)
189 		cpumask_check(n);
190 	return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
191 }
192 
193 /**
194  * cpumask_next_zero - get the next unset cpu in a cpumask
195  * @n: the cpu prior to the place to search (ie. return will be > @n)
196  * @srcp: the cpumask pointer
197  *
198  * Returns >= nr_cpu_ids if no further cpus unset.
199  */
200 static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
201 {
202 	/* -1 is a legal arg here. */
203 	if (n != -1)
204 		cpumask_check(n);
205 	return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
206 }
207 
208 int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
209 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
210 int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp);
211 
212 /**
213  * for_each_cpu - iterate over every cpu in a mask
214  * @cpu: the (optionally unsigned) integer iterator
215  * @mask: the cpumask pointer
216  *
217  * After the loop, cpu is >= nr_cpu_ids.
218  */
219 #define for_each_cpu(cpu, mask)				\
220 	for ((cpu) = -1;				\
221 		(cpu) = cpumask_next((cpu), (mask)),	\
222 		(cpu) < nr_cpu_ids;)
223 
224 /**
225  * for_each_cpu_not - iterate over every cpu in a complemented mask
226  * @cpu: the (optionally unsigned) integer iterator
227  * @mask: the cpumask pointer
228  *
229  * After the loop, cpu is >= nr_cpu_ids.
230  */
231 #define for_each_cpu_not(cpu, mask)				\
232 	for ((cpu) = -1;					\
233 		(cpu) = cpumask_next_zero((cpu), (mask)),	\
234 		(cpu) < nr_cpu_ids;)
235 
236 /**
237  * for_each_cpu_and - iterate over every cpu in both masks
238  * @cpu: the (optionally unsigned) integer iterator
239  * @mask: the first cpumask pointer
240  * @and: the second cpumask pointer
241  *
242  * This saves a temporary CPU mask in many places.  It is equivalent to:
243  *	struct cpumask tmp;
244  *	cpumask_and(&tmp, &mask, &and);
245  *	for_each_cpu(cpu, &tmp)
246  *		...
247  *
248  * After the loop, cpu is >= nr_cpu_ids.
249  */
250 #define for_each_cpu_and(cpu, mask, and)				\
251 	for ((cpu) = -1;						\
252 		(cpu) = cpumask_next_and((cpu), (mask), (and)),		\
253 		(cpu) < nr_cpu_ids;)
254 #endif /* SMP */
255 
256 #define CPU_BITS_NONE						\
257 {								\
258 	[0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL			\
259 }
260 
261 #define CPU_BITS_CPU0						\
262 {								\
263 	[0] =  1UL						\
264 }
265 
266 /**
267  * cpumask_set_cpu - set a cpu in a cpumask
268  * @cpu: cpu number (< nr_cpu_ids)
269  * @dstp: the cpumask pointer
270  */
271 static inline void cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
272 {
273 	set_bit(cpumask_check(cpu), cpumask_bits(dstp));
274 }
275 
276 /**
277  * cpumask_clear_cpu - clear a cpu in a cpumask
278  * @cpu: cpu number (< nr_cpu_ids)
279  * @dstp: the cpumask pointer
280  */
281 static inline void cpumask_clear_cpu(int cpu, struct cpumask *dstp)
282 {
283 	clear_bit(cpumask_check(cpu), cpumask_bits(dstp));
284 }
285 
286 /**
287  * cpumask_test_cpu - test for a cpu in a cpumask
288  * @cpu: cpu number (< nr_cpu_ids)
289  * @cpumask: the cpumask pointer
290  *
291  * Returns 1 if @cpu is set in @cpumask, else returns 0
292  *
293  * No static inline type checking - see Subtlety (1) above.
294  */
295 #define cpumask_test_cpu(cpu, cpumask) \
296 	test_bit(cpumask_check(cpu), cpumask_bits((cpumask)))
297 
298 /**
299  * cpumask_test_and_set_cpu - atomically test and set a cpu in a cpumask
300  * @cpu: cpu number (< nr_cpu_ids)
301  * @cpumask: the cpumask pointer
302  *
303  * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
304  *
305  * test_and_set_bit wrapper for cpumasks.
306  */
307 static inline int cpumask_test_and_set_cpu(int cpu, struct cpumask *cpumask)
308 {
309 	return test_and_set_bit(cpumask_check(cpu), cpumask_bits(cpumask));
310 }
311 
312 /**
313  * cpumask_test_and_clear_cpu - atomically test and clear a cpu in a cpumask
314  * @cpu: cpu number (< nr_cpu_ids)
315  * @cpumask: the cpumask pointer
316  *
317  * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
318  *
319  * test_and_clear_bit wrapper for cpumasks.
320  */
321 static inline int cpumask_test_and_clear_cpu(int cpu, struct cpumask *cpumask)
322 {
323 	return test_and_clear_bit(cpumask_check(cpu), cpumask_bits(cpumask));
324 }
325 
326 /**
327  * cpumask_setall - set all cpus (< nr_cpu_ids) in a cpumask
328  * @dstp: the cpumask pointer
329  */
330 static inline void cpumask_setall(struct cpumask *dstp)
331 {
332 	bitmap_fill(cpumask_bits(dstp), nr_cpumask_bits);
333 }
334 
335 /**
336  * cpumask_clear - clear all cpus (< nr_cpu_ids) in a cpumask
337  * @dstp: the cpumask pointer
338  */
339 static inline void cpumask_clear(struct cpumask *dstp)
340 {
341 	bitmap_zero(cpumask_bits(dstp), nr_cpumask_bits);
342 }
343 
344 /**
345  * cpumask_and - *dstp = *src1p & *src2p
346  * @dstp: the cpumask result
347  * @src1p: the first input
348  * @src2p: the second input
349  *
350  * If *@dstp is empty, returns 0, else returns 1
351  */
352 static inline int cpumask_and(struct cpumask *dstp,
353 			       const struct cpumask *src1p,
354 			       const struct cpumask *src2p)
355 {
356 	return bitmap_and(cpumask_bits(dstp), cpumask_bits(src1p),
357 				       cpumask_bits(src2p), nr_cpumask_bits);
358 }
359 
360 /**
361  * cpumask_or - *dstp = *src1p | *src2p
362  * @dstp: the cpumask result
363  * @src1p: the first input
364  * @src2p: the second input
365  */
366 static inline void cpumask_or(struct cpumask *dstp, const struct cpumask *src1p,
367 			      const struct cpumask *src2p)
368 {
369 	bitmap_or(cpumask_bits(dstp), cpumask_bits(src1p),
370 				      cpumask_bits(src2p), nr_cpumask_bits);
371 }
372 
373 /**
374  * cpumask_xor - *dstp = *src1p ^ *src2p
375  * @dstp: the cpumask result
376  * @src1p: the first input
377  * @src2p: the second input
378  */
379 static inline void cpumask_xor(struct cpumask *dstp,
380 			       const struct cpumask *src1p,
381 			       const struct cpumask *src2p)
382 {
383 	bitmap_xor(cpumask_bits(dstp), cpumask_bits(src1p),
384 				       cpumask_bits(src2p), nr_cpumask_bits);
385 }
386 
387 /**
388  * cpumask_andnot - *dstp = *src1p & ~*src2p
389  * @dstp: the cpumask result
390  * @src1p: the first input
391  * @src2p: the second input
392  *
393  * If *@dstp is empty, returns 0, else returns 1
394  */
395 static inline int cpumask_andnot(struct cpumask *dstp,
396 				  const struct cpumask *src1p,
397 				  const struct cpumask *src2p)
398 {
399 	return bitmap_andnot(cpumask_bits(dstp), cpumask_bits(src1p),
400 					  cpumask_bits(src2p), nr_cpumask_bits);
401 }
402 
403 /**
404  * cpumask_complement - *dstp = ~*srcp
405  * @dstp: the cpumask result
406  * @srcp: the input to invert
407  */
408 static inline void cpumask_complement(struct cpumask *dstp,
409 				      const struct cpumask *srcp)
410 {
411 	bitmap_complement(cpumask_bits(dstp), cpumask_bits(srcp),
412 					      nr_cpumask_bits);
413 }
414 
415 /**
416  * cpumask_equal - *src1p == *src2p
417  * @src1p: the first input
418  * @src2p: the second input
419  */
420 static inline bool cpumask_equal(const struct cpumask *src1p,
421 				const struct cpumask *src2p)
422 {
423 	return bitmap_equal(cpumask_bits(src1p), cpumask_bits(src2p),
424 						 nr_cpumask_bits);
425 }
426 
427 /**
428  * cpumask_intersects - (*src1p & *src2p) != 0
429  * @src1p: the first input
430  * @src2p: the second input
431  */
432 static inline bool cpumask_intersects(const struct cpumask *src1p,
433 				     const struct cpumask *src2p)
434 {
435 	return bitmap_intersects(cpumask_bits(src1p), cpumask_bits(src2p),
436 						      nr_cpumask_bits);
437 }
438 
439 /**
440  * cpumask_subset - (*src1p & ~*src2p) == 0
441  * @src1p: the first input
442  * @src2p: the second input
443  *
444  * Returns 1 if *@src1p is a subset of *@src2p, else returns 0
445  */
446 static inline int cpumask_subset(const struct cpumask *src1p,
447 				 const struct cpumask *src2p)
448 {
449 	return bitmap_subset(cpumask_bits(src1p), cpumask_bits(src2p),
450 						  nr_cpumask_bits);
451 }
452 
453 /**
454  * cpumask_empty - *srcp == 0
455  * @srcp: the cpumask to that all cpus < nr_cpu_ids are clear.
456  */
457 static inline bool cpumask_empty(const struct cpumask *srcp)
458 {
459 	return bitmap_empty(cpumask_bits(srcp), nr_cpumask_bits);
460 }
461 
462 /**
463  * cpumask_full - *srcp == 0xFFFFFFFF...
464  * @srcp: the cpumask to that all cpus < nr_cpu_ids are set.
465  */
466 static inline bool cpumask_full(const struct cpumask *srcp)
467 {
468 	return bitmap_full(cpumask_bits(srcp), nr_cpumask_bits);
469 }
470 
471 /**
472  * cpumask_weight - Count of bits in *srcp
473  * @srcp: the cpumask to count bits (< nr_cpu_ids) in.
474  */
475 static inline unsigned int cpumask_weight(const struct cpumask *srcp)
476 {
477 	return bitmap_weight(cpumask_bits(srcp), nr_cpumask_bits);
478 }
479 
480 /**
481  * cpumask_shift_right - *dstp = *srcp >> n
482  * @dstp: the cpumask result
483  * @srcp: the input to shift
484  * @n: the number of bits to shift by
485  */
486 static inline void cpumask_shift_right(struct cpumask *dstp,
487 				       const struct cpumask *srcp, int n)
488 {
489 	bitmap_shift_right(cpumask_bits(dstp), cpumask_bits(srcp), n,
490 					       nr_cpumask_bits);
491 }
492 
493 /**
494  * cpumask_shift_left - *dstp = *srcp << n
495  * @dstp: the cpumask result
496  * @srcp: the input to shift
497  * @n: the number of bits to shift by
498  */
499 static inline void cpumask_shift_left(struct cpumask *dstp,
500 				      const struct cpumask *srcp, int n)
501 {
502 	bitmap_shift_left(cpumask_bits(dstp), cpumask_bits(srcp), n,
503 					      nr_cpumask_bits);
504 }
505 
506 /**
507  * cpumask_copy - *dstp = *srcp
508  * @dstp: the result
509  * @srcp: the input cpumask
510  */
511 static inline void cpumask_copy(struct cpumask *dstp,
512 				const struct cpumask *srcp)
513 {
514 	bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), nr_cpumask_bits);
515 }
516 
517 /**
518  * cpumask_any - pick a "random" cpu from *srcp
519  * @srcp: the input cpumask
520  *
521  * Returns >= nr_cpu_ids if no cpus set.
522  */
523 #define cpumask_any(srcp) cpumask_first(srcp)
524 
525 /**
526  * cpumask_first_and - return the first cpu from *srcp1 & *srcp2
527  * @src1p: the first input
528  * @src2p: the second input
529  *
530  * Returns >= nr_cpu_ids if no cpus set in both.  See also cpumask_next_and().
531  */
532 #define cpumask_first_and(src1p, src2p) cpumask_next_and(-1, (src1p), (src2p))
533 
534 /**
535  * cpumask_any_and - pick a "random" cpu from *mask1 & *mask2
536  * @mask1: the first input cpumask
537  * @mask2: the second input cpumask
538  *
539  * Returns >= nr_cpu_ids if no cpus set.
540  */
541 #define cpumask_any_and(mask1, mask2) cpumask_first_and((mask1), (mask2))
542 
543 /**
544  * cpumask_of - the cpumask containing just a given cpu
545  * @cpu: the cpu (<= nr_cpu_ids)
546  */
547 #define cpumask_of(cpu) (get_cpu_mask(cpu))
548 
549 /**
550  * cpumask_parse_user - extract a cpumask from a user string
551  * @buf: the buffer to extract from
552  * @len: the length of the buffer
553  * @dstp: the cpumask to set.
554  *
555  * Returns -errno, or 0 for success.
556  */
557 static inline int cpumask_parse_user(const char __user *buf, int len,
558 				     struct cpumask *dstp)
559 {
560 	return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpu_ids);
561 }
562 
563 /**
564  * cpumask_parselist_user - extract a cpumask from a user string
565  * @buf: the buffer to extract from
566  * @len: the length of the buffer
567  * @dstp: the cpumask to set.
568  *
569  * Returns -errno, or 0 for success.
570  */
571 static inline int cpumask_parselist_user(const char __user *buf, int len,
572 				     struct cpumask *dstp)
573 {
574 	return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
575 				     nr_cpu_ids);
576 }
577 
578 /**
579  * cpumask_parse - extract a cpumask from from a string
580  * @buf: the buffer to extract from
581  * @dstp: the cpumask to set.
582  *
583  * Returns -errno, or 0 for success.
584  */
585 static inline int cpumask_parse(const char *buf, struct cpumask *dstp)
586 {
587 	char *nl = strchr(buf, '\n');
588 	unsigned int len = nl ? (unsigned int)(nl - buf) : strlen(buf);
589 
590 	return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpu_ids);
591 }
592 
593 /**
594  * cpulist_parse - extract a cpumask from a user string of ranges
595  * @buf: the buffer to extract from
596  * @dstp: the cpumask to set.
597  *
598  * Returns -errno, or 0 for success.
599  */
600 static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
601 {
602 	return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpu_ids);
603 }
604 
605 /**
606  * cpumask_size - size to allocate for a 'struct cpumask' in bytes
607  *
608  * This will eventually be a runtime variable, depending on nr_cpu_ids.
609  */
610 static inline size_t cpumask_size(void)
611 {
612 	/* FIXME: Once all cpumask assignments are eliminated, this
613 	 * can be nr_cpumask_bits */
614 	return BITS_TO_LONGS(NR_CPUS) * sizeof(long);
615 }
616 
617 /*
618  * cpumask_var_t: struct cpumask for stack usage.
619  *
620  * Oh, the wicked games we play!  In order to make kernel coding a
621  * little more difficult, we typedef cpumask_var_t to an array or a
622  * pointer: doing &mask on an array is a noop, so it still works.
623  *
624  * ie.
625  *	cpumask_var_t tmpmask;
626  *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
627  *		return -ENOMEM;
628  *
629  *	  ... use 'tmpmask' like a normal struct cpumask * ...
630  *
631  *	free_cpumask_var(tmpmask);
632  *
633  *
634  * However, one notable exception is there. alloc_cpumask_var() allocates
635  * only nr_cpumask_bits bits (in the other hand, real cpumask_t always has
636  * NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t.
637  *
638  *	cpumask_var_t tmpmask;
639  *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
640  *		return -ENOMEM;
641  *
642  *	var = *tmpmask;
643  *
644  * This code makes NR_CPUS length memcopy and brings to a memory corruption.
645  * cpumask_copy() provide safe copy functionality.
646  *
647  * Note that there is another evil here: If you define a cpumask_var_t
648  * as a percpu variable then the way to obtain the address of the cpumask
649  * structure differently influences what this_cpu_* operation needs to be
650  * used. Please use this_cpu_cpumask_var_t in those cases. The direct use
651  * of this_cpu_ptr() or this_cpu_read() will lead to failures when the
652  * other type of cpumask_var_t implementation is configured.
653  */
654 #ifdef CONFIG_CPUMASK_OFFSTACK
655 typedef struct cpumask *cpumask_var_t;
656 
657 #define this_cpu_cpumask_var_ptr(x) this_cpu_read(x)
658 
659 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
660 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
661 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
662 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
663 void alloc_bootmem_cpumask_var(cpumask_var_t *mask);
664 void free_cpumask_var(cpumask_var_t mask);
665 void free_bootmem_cpumask_var(cpumask_var_t mask);
666 
667 #else
668 typedef struct cpumask cpumask_var_t[1];
669 
670 #define this_cpu_cpumask_var_ptr(x) this_cpu_ptr(x)
671 
672 static inline bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
673 {
674 	return true;
675 }
676 
677 static inline bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
678 					  int node)
679 {
680 	return true;
681 }
682 
683 static inline bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
684 {
685 	cpumask_clear(*mask);
686 	return true;
687 }
688 
689 static inline bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
690 					  int node)
691 {
692 	cpumask_clear(*mask);
693 	return true;
694 }
695 
696 static inline void alloc_bootmem_cpumask_var(cpumask_var_t *mask)
697 {
698 }
699 
700 static inline void free_cpumask_var(cpumask_var_t mask)
701 {
702 }
703 
704 static inline void free_bootmem_cpumask_var(cpumask_var_t mask)
705 {
706 }
707 #endif /* CONFIG_CPUMASK_OFFSTACK */
708 
709 /* It's common to want to use cpu_all_mask in struct member initializers,
710  * so it has to refer to an address rather than a pointer. */
711 extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
712 #define cpu_all_mask to_cpumask(cpu_all_bits)
713 
714 /* First bits of cpu_bit_bitmap are in fact unset. */
715 #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
716 
717 #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
718 #define for_each_online_cpu(cpu)   for_each_cpu((cpu), cpu_online_mask)
719 #define for_each_present_cpu(cpu)  for_each_cpu((cpu), cpu_present_mask)
720 
721 /* Wrappers for arch boot code to manipulate normally-constant masks */
722 void set_cpu_possible(unsigned int cpu, bool possible);
723 void set_cpu_present(unsigned int cpu, bool present);
724 void set_cpu_online(unsigned int cpu, bool online);
725 void set_cpu_active(unsigned int cpu, bool active);
726 void init_cpu_present(const struct cpumask *src);
727 void init_cpu_possible(const struct cpumask *src);
728 void init_cpu_online(const struct cpumask *src);
729 
730 /**
731  * to_cpumask - convert an NR_CPUS bitmap to a struct cpumask *
732  * @bitmap: the bitmap
733  *
734  * There are a few places where cpumask_var_t isn't appropriate and
735  * static cpumasks must be used (eg. very early boot), yet we don't
736  * expose the definition of 'struct cpumask'.
737  *
738  * This does the conversion, and can be used as a constant initializer.
739  */
740 #define to_cpumask(bitmap)						\
741 	((struct cpumask *)(1 ? (bitmap)				\
742 			    : (void *)sizeof(__check_is_bitmap(bitmap))))
743 
744 static inline int __check_is_bitmap(const unsigned long *bitmap)
745 {
746 	return 1;
747 }
748 
749 /*
750  * Special-case data structure for "single bit set only" constant CPU masks.
751  *
752  * We pre-generate all the 64 (or 32) possible bit positions, with enough
753  * padding to the left and the right, and return the constant pointer
754  * appropriately offset.
755  */
756 extern const unsigned long
757 	cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)];
758 
759 static inline const struct cpumask *get_cpu_mask(unsigned int cpu)
760 {
761 	const unsigned long *p = cpu_bit_bitmap[1 + cpu % BITS_PER_LONG];
762 	p -= cpu / BITS_PER_LONG;
763 	return to_cpumask(p);
764 }
765 
766 #define cpu_is_offline(cpu)	unlikely(!cpu_online(cpu))
767 
768 #if NR_CPUS <= BITS_PER_LONG
769 #define CPU_BITS_ALL						\
770 {								\
771 	[BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD	\
772 }
773 
774 #else /* NR_CPUS > BITS_PER_LONG */
775 
776 #define CPU_BITS_ALL						\
777 {								\
778 	[0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,		\
779 	[BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD		\
780 }
781 #endif /* NR_CPUS > BITS_PER_LONG */
782 
783 /**
784  * cpumap_print_to_pagebuf  - copies the cpumask into the buffer either
785  *	as comma-separated list of cpus or hex values of cpumask
786  * @list: indicates whether the cpumap must be list
787  * @mask: the cpumask to copy
788  * @buf: the buffer to copy into
789  *
790  * Returns the length of the (null-terminated) @buf string, zero if
791  * nothing is copied.
792  */
793 static inline ssize_t
794 cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask)
795 {
796 	return bitmap_print_to_pagebuf(list, buf, cpumask_bits(mask),
797 				      nr_cpu_ids);
798 }
799 
800 /*
801  *
802  * From here down, all obsolete.  Use cpumask_ variants!
803  *
804  */
805 #ifndef CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS
806 #define cpumask_of_cpu(cpu) (*get_cpu_mask(cpu))
807 
808 #define CPU_MASK_LAST_WORD BITMAP_LAST_WORD_MASK(NR_CPUS)
809 
810 #if NR_CPUS <= BITS_PER_LONG
811 
812 #define CPU_MASK_ALL							\
813 (cpumask_t) { {								\
814 	[BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD			\
815 } }
816 
817 #else
818 
819 #define CPU_MASK_ALL							\
820 (cpumask_t) { {								\
821 	[0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,			\
822 	[BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD			\
823 } }
824 
825 #endif
826 
827 #define CPU_MASK_NONE							\
828 (cpumask_t) { {								\
829 	[0 ... BITS_TO_LONGS(NR_CPUS)-1] =  0UL				\
830 } }
831 
832 #define CPU_MASK_CPU0							\
833 (cpumask_t) { {								\
834 	[0] =  1UL							\
835 } }
836 
837 #if NR_CPUS == 1
838 #define first_cpu(src)		({ (void)(src); 0; })
839 #define next_cpu(n, src)	({ (void)(src); 1; })
840 #define any_online_cpu(mask)	0
841 #define for_each_cpu_mask(cpu, mask)	\
842 	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
843 #else /* NR_CPUS > 1 */
844 int __first_cpu(const cpumask_t *srcp);
845 int __next_cpu(int n, const cpumask_t *srcp);
846 
847 #define first_cpu(src)		__first_cpu(&(src))
848 #define next_cpu(n, src)	__next_cpu((n), &(src))
849 #define any_online_cpu(mask) cpumask_any_and(&mask, cpu_online_mask)
850 #define for_each_cpu_mask(cpu, mask)			\
851 	for ((cpu) = -1;				\
852 		(cpu) = next_cpu((cpu), (mask)),	\
853 		(cpu) < NR_CPUS; )
854 #endif /* SMP */
855 
856 #if NR_CPUS <= 64
857 
858 #define for_each_cpu_mask_nr(cpu, mask)	for_each_cpu_mask(cpu, mask)
859 
860 #else /* NR_CPUS > 64 */
861 
862 int __next_cpu_nr(int n, const cpumask_t *srcp);
863 #define for_each_cpu_mask_nr(cpu, mask)			\
864 	for ((cpu) = -1;				\
865 		(cpu) = __next_cpu_nr((cpu), &(mask)),	\
866 		(cpu) < nr_cpu_ids; )
867 
868 #endif /* NR_CPUS > 64 */
869 
870 #define cpus_addr(src) ((src).bits)
871 
872 #define cpu_set(cpu, dst) __cpu_set((cpu), &(dst))
873 static inline void __cpu_set(int cpu, volatile cpumask_t *dstp)
874 {
875 	set_bit(cpu, dstp->bits);
876 }
877 
878 #define cpu_clear(cpu, dst) __cpu_clear((cpu), &(dst))
879 static inline void __cpu_clear(int cpu, volatile cpumask_t *dstp)
880 {
881 	clear_bit(cpu, dstp->bits);
882 }
883 
884 #define cpus_setall(dst) __cpus_setall(&(dst), NR_CPUS)
885 static inline void __cpus_setall(cpumask_t *dstp, unsigned int nbits)
886 {
887 	bitmap_fill(dstp->bits, nbits);
888 }
889 
890 #define cpus_clear(dst) __cpus_clear(&(dst), NR_CPUS)
891 static inline void __cpus_clear(cpumask_t *dstp, unsigned int nbits)
892 {
893 	bitmap_zero(dstp->bits, nbits);
894 }
895 
896 /* No static inline type checking - see Subtlety (1) above. */
897 #define cpu_isset(cpu, cpumask) test_bit((cpu), (cpumask).bits)
898 
899 #define cpu_test_and_set(cpu, cpumask) __cpu_test_and_set((cpu), &(cpumask))
900 static inline int __cpu_test_and_set(int cpu, cpumask_t *addr)
901 {
902 	return test_and_set_bit(cpu, addr->bits);
903 }
904 
905 #define cpus_and(dst, src1, src2) __cpus_and(&(dst), &(src1), &(src2), NR_CPUS)
906 static inline int __cpus_and(cpumask_t *dstp, const cpumask_t *src1p,
907 					const cpumask_t *src2p, unsigned int nbits)
908 {
909 	return bitmap_and(dstp->bits, src1p->bits, src2p->bits, nbits);
910 }
911 
912 #define cpus_or(dst, src1, src2) __cpus_or(&(dst), &(src1), &(src2), NR_CPUS)
913 static inline void __cpus_or(cpumask_t *dstp, const cpumask_t *src1p,
914 					const cpumask_t *src2p, unsigned int nbits)
915 {
916 	bitmap_or(dstp->bits, src1p->bits, src2p->bits, nbits);
917 }
918 
919 #define cpus_xor(dst, src1, src2) __cpus_xor(&(dst), &(src1), &(src2), NR_CPUS)
920 static inline void __cpus_xor(cpumask_t *dstp, const cpumask_t *src1p,
921 					const cpumask_t *src2p, unsigned int nbits)
922 {
923 	bitmap_xor(dstp->bits, src1p->bits, src2p->bits, nbits);
924 }
925 
926 #define cpus_andnot(dst, src1, src2) \
927 				__cpus_andnot(&(dst), &(src1), &(src2), NR_CPUS)
928 static inline int __cpus_andnot(cpumask_t *dstp, const cpumask_t *src1p,
929 					const cpumask_t *src2p, unsigned int nbits)
930 {
931 	return bitmap_andnot(dstp->bits, src1p->bits, src2p->bits, nbits);
932 }
933 
934 #define cpus_equal(src1, src2) __cpus_equal(&(src1), &(src2), NR_CPUS)
935 static inline int __cpus_equal(const cpumask_t *src1p,
936 					const cpumask_t *src2p, unsigned int nbits)
937 {
938 	return bitmap_equal(src1p->bits, src2p->bits, nbits);
939 }
940 
941 #define cpus_intersects(src1, src2) __cpus_intersects(&(src1), &(src2), NR_CPUS)
942 static inline int __cpus_intersects(const cpumask_t *src1p,
943 					const cpumask_t *src2p, unsigned int nbits)
944 {
945 	return bitmap_intersects(src1p->bits, src2p->bits, nbits);
946 }
947 
948 #define cpus_subset(src1, src2) __cpus_subset(&(src1), &(src2), NR_CPUS)
949 static inline int __cpus_subset(const cpumask_t *src1p,
950 					const cpumask_t *src2p, unsigned int nbits)
951 {
952 	return bitmap_subset(src1p->bits, src2p->bits, nbits);
953 }
954 
955 #define cpus_empty(src) __cpus_empty(&(src), NR_CPUS)
956 static inline int __cpus_empty(const cpumask_t *srcp, unsigned int nbits)
957 {
958 	return bitmap_empty(srcp->bits, nbits);
959 }
960 
961 #define cpus_weight(cpumask) __cpus_weight(&(cpumask), NR_CPUS)
962 static inline int __cpus_weight(const cpumask_t *srcp, unsigned int nbits)
963 {
964 	return bitmap_weight(srcp->bits, nbits);
965 }
966 
967 #define cpus_shift_left(dst, src, n) \
968 			__cpus_shift_left(&(dst), &(src), (n), NR_CPUS)
969 static inline void __cpus_shift_left(cpumask_t *dstp,
970 					const cpumask_t *srcp, int n, int nbits)
971 {
972 	bitmap_shift_left(dstp->bits, srcp->bits, n, nbits);
973 }
974 #endif /* !CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS */
975 
976 #endif /* __LINUX_CPUMASK_H */
977