root/include/linux/cpumask.h

INCLUDED FROM

DEFINITIONS

1. cpumask_check
2. cpumask_first
3. cpumask_next
4. cpumask_next_zero
5. cpumask_next_and
6. cpumask_any_but
7. cpumask_set_cpu_local_first
8. cpumask_first
9. cpumask_next
10. cpumask_next_zero
11. cpumask_set_cpu
12. cpumask_clear_cpu
13. cpumask_test_and_set_cpu
14. cpumask_test_and_clear_cpu
15. cpumask_setall
16. cpumask_clear
17. cpumask_and
18. cpumask_or
19. cpumask_xor
20. cpumask_andnot
21. cpumask_complement
22. cpumask_equal
23. cpumask_intersects
24. cpumask_subset
25. cpumask_empty
26. cpumask_full
27. cpumask_weight
28. cpumask_shift_right
29. cpumask_shift_left
30. cpumask_copy
31. cpumask_scnprintf
32. cpumask_parse_user
33. cpumask_parselist_user
34. cpulist_scnprintf
35. cpumask_parse
36. cpulist_parse
37. cpumask_size
38. alloc_cpumask_var
39. alloc_cpumask_var_node
40. zalloc_cpumask_var
41. zalloc_cpumask_var_node
42. alloc_bootmem_cpumask_var
43. free_cpumask_var
44. free_bootmem_cpumask_var
45. __check_is_bitmap
46. get_cpu_mask
47. __cpu_set
48. __cpu_clear
49. __cpus_setall
50. __cpus_clear
51. __cpu_test_and_set
52. __cpus_and
53. __cpus_or
54. __cpus_xor
55. __cpus_andnot
56. __cpus_equal
57. __cpus_intersects
58. __cpus_subset
59. __cpus_empty
60. __cpus_weight
61. __cpus_shift_left

#ifndef __LINUX_CPUMASK_H
#define __LINUX_CPUMASK_H

/*
 * Cpumasks provide a bitmap suitable for representing the
 * set of CPU's in a system, one bit position per CPU number.  In general,
 * only nr_cpu_ids (<= NR_CPUS) bits are valid.
 */
#include <linux/kernel.h>
#include <linux/threads.h>
#include <linux/bitmap.h>
#include <linux/bug.h>

typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;

/**
 * cpumask_bits - get the bits in a cpumask
 * @maskp: the struct cpumask *
 *
 * You should only assume nr_cpu_ids bits of this mask are valid.  This is
 * a macro so it's const-correct.
 */
#define cpumask_bits(maskp) ((maskp)->bits)

#if NR_CPUS == 1
#define nr_cpu_ids              1
#else
extern int nr_cpu_ids;
#endif

#ifdef CONFIG_CPUMASK_OFFSTACK
/* Assuming NR_CPUS is huge, a runtime limit is more efficient.  Also,
 * not all bits may be allocated. */
#define nr_cpumask_bits nr_cpu_ids
#else
#define nr_cpumask_bits NR_CPUS
#endif

/*
 * The following particular system cpumasks and operations manage
 * possible, present, active and online cpus.
 *
 *     cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
 *     cpu_present_mask - has bit 'cpu' set iff cpu is populated
 *     cpu_online_mask  - has bit 'cpu' set iff cpu available to scheduler
 *     cpu_active_mask  - has bit 'cpu' set iff cpu available to migration
 *
 *  If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
 *
 *  The cpu_possible_mask is fixed at boot time, as the set of CPU id's
 *  that it is possible might ever be plugged in at anytime during the
 *  life of that system boot.  The cpu_present_mask is dynamic(*),
 *  representing which CPUs are currently plugged in.  And
 *  cpu_online_mask is the dynamic subset of cpu_present_mask,
 *  indicating those CPUs available for scheduling.
 *
 *  If HOTPLUG is enabled, then cpu_possible_mask is forced to have
 *  all NR_CPUS bits set, otherwise it is just the set of CPUs that
 *  ACPI reports present at boot.
 *
 *  If HOTPLUG is enabled, then cpu_present_mask varies dynamically,
 *  depending on what ACPI reports as currently plugged in, otherwise
 *  cpu_present_mask is just a copy of cpu_possible_mask.
 *
 *  (*) Well, cpu_present_mask is dynamic in the hotplug case.  If not
 *      hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
 *
 * Subtleties:
 * 1) UP arch's (NR_CPUS == 1, CONFIG_SMP not defined) hardcode
 *    assumption that their single CPU is online.  The UP
 *    cpu_{online,possible,present}_masks are placebos.  Changing them
 *    will have no useful affect on the following num_*_cpus()
 *    and cpu_*() macros in the UP case.  This ugliness is a UP
 *    optimization - don't waste any instructions or memory references
 *    asking if you're online or how many CPUs there are if there is
 *    only one CPU.
 */

extern const struct cpumask *const cpu_possible_mask;
extern const struct cpumask *const cpu_online_mask;
extern const struct cpumask *const cpu_present_mask;
extern const struct cpumask *const cpu_active_mask;

#if NR_CPUS > 1
#define num_online_cpus()       cpumask_weight(cpu_online_mask)
#define num_possible_cpus()     cpumask_weight(cpu_possible_mask)
#define num_present_cpus()      cpumask_weight(cpu_present_mask)
#define num_active_cpus()       cpumask_weight(cpu_active_mask)
#define cpu_online(cpu)         cpumask_test_cpu((cpu), cpu_online_mask)
#define cpu_possible(cpu)       cpumask_test_cpu((cpu), cpu_possible_mask)
#define cpu_present(cpu)        cpumask_test_cpu((cpu), cpu_present_mask)
#define cpu_active(cpu)         cpumask_test_cpu((cpu), cpu_active_mask)
#else
#define num_online_cpus()       1U
#define num_possible_cpus()     1U
#define num_present_cpus()      1U
#define num_active_cpus()       1U
#define cpu_online(cpu)         ((cpu) == 0)
#define cpu_possible(cpu)       ((cpu) == 0)
#define cpu_present(cpu)        ((cpu) == 0)
#define cpu_active(cpu)         ((cpu) == 0)
#endif

/* verify cpu argument to cpumask_* operators */
static inline unsigned int cpumask_check(unsigned int cpu)
{
#ifdef CONFIG_DEBUG_PER_CPU_MAPS
        WARN_ON_ONCE(cpu >= nr_cpumask_bits);
#endif /* CONFIG_DEBUG_PER_CPU_MAPS */
        return cpu;
}

#if NR_CPUS == 1
/* Uniprocessor.  Assume all masks are "1". */
static inline unsigned int cpumask_first(const struct cpumask *srcp)
{
        return 0;
}

/* Valid inputs for n are -1 and 0. */
static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
{
        return n+1;
}

static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
{
        return n+1;
}

static inline unsigned int cpumask_next_and(int n,
                                            const struct cpumask *srcp,
                                            const struct cpumask *andp)
{
        return n+1;
}

/* cpu must be a valid cpu, ie 0, so there's no other choice. */
static inline unsigned int cpumask_any_but(const struct cpumask *mask,
                                           unsigned int cpu)
{
        return 1;
}

static inline int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
{
        set_bit(0, cpumask_bits(dstp));

        return 0;
}

#define for_each_cpu(cpu, mask)                 \
        for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
#define for_each_cpu_not(cpu, mask)             \
        for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
#define for_each_cpu_and(cpu, mask, and)        \
        for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)and)
#else
/**
 * cpumask_first - get the first cpu in a cpumask
 * @srcp: the cpumask pointer
 *
 * Returns >= nr_cpu_ids if no cpus set.
 */
static inline unsigned int cpumask_first(const struct cpumask *srcp)
{
        return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits);
}

/**
 * cpumask_next - get the next cpu in a cpumask
 * @n: the cpu prior to the place to search (ie. return will be > @n)
 * @srcp: the cpumask pointer
 *
 * Returns >= nr_cpu_ids if no further cpus set.
 */
static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
{
        /* -1 is a legal arg here. */
        if (n != -1)
                cpumask_check(n);
        return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
}

/**
 * cpumask_next_zero - get the next unset cpu in a cpumask
 * @n: the cpu prior to the place to search (ie. return will be > @n)
 * @srcp: the cpumask pointer
 *
 * Returns >= nr_cpu_ids if no further cpus unset.
 */
static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
{
        /* -1 is a legal arg here. */
        if (n != -1)
                cpumask_check(n);
        return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
}

int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp);

/**
 * for_each_cpu - iterate over every cpu in a mask
 * @cpu: the (optionally unsigned) integer iterator
 * @mask: the cpumask pointer
 *
 * After the loop, cpu is >= nr_cpu_ids.
 */
#define for_each_cpu(cpu, mask)                         \
        for ((cpu) = -1;                                \
                (cpu) = cpumask_next((cpu), (mask)),    \
                (cpu) < nr_cpu_ids;)

/**
 * for_each_cpu_not - iterate over every cpu in a complemented mask
 * @cpu: the (optionally unsigned) integer iterator
 * @mask: the cpumask pointer
 *
 * After the loop, cpu is >= nr_cpu_ids.
 */
#define for_each_cpu_not(cpu, mask)                             \
        for ((cpu) = -1;                                        \
                (cpu) = cpumask_next_zero((cpu), (mask)),       \
                (cpu) < nr_cpu_ids;)

/**
 * for_each_cpu_and - iterate over every cpu in both masks
 * @cpu: the (optionally unsigned) integer iterator
 * @mask: the first cpumask pointer
 * @and: the second cpumask pointer
 *
 * This saves a temporary CPU mask in many places.  It is equivalent to:
 *      struct cpumask tmp;
 *      cpumask_and(&tmp, &mask, &and);
 *      for_each_cpu(cpu, &tmp)
 *              ...
 *
 * After the loop, cpu is >= nr_cpu_ids.
 */
#define for_each_cpu_and(cpu, mask, and)                                \
        for ((cpu) = -1;                                                \
                (cpu) = cpumask_next_and((cpu), (mask), (and)),         \
                (cpu) < nr_cpu_ids;)
#endif /* SMP */

#define CPU_BITS_NONE                                           \
{                                                               \
        [0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL                  \
}

#define CPU_BITS_CPU0                                           \
{                                                               \
        [0] =  1UL                                              \
}

/**
 * cpumask_set_cpu - set a cpu in a cpumask
 * @cpu: cpu number (< nr_cpu_ids)
 * @dstp: the cpumask pointer
 */
static inline void cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
{
        set_bit(cpumask_check(cpu), cpumask_bits(dstp));
}

/**
 * cpumask_clear_cpu - clear a cpu in a cpumask
 * @cpu: cpu number (< nr_cpu_ids)
 * @dstp: the cpumask pointer
 */
static inline void cpumask_clear_cpu(int cpu, struct cpumask *dstp)
{
        clear_bit(cpumask_check(cpu), cpumask_bits(dstp));
}

/**
 * cpumask_test_cpu - test for a cpu in a cpumask
 * @cpu: cpu number (< nr_cpu_ids)
 * @cpumask: the cpumask pointer
 *
 * Returns 1 if @cpu is set in @cpumask, else returns 0
 *
 * No static inline type checking - see Subtlety (1) above.
 */
#define cpumask_test_cpu(cpu, cpumask) \
        test_bit(cpumask_check(cpu), cpumask_bits((cpumask)))

/**
 * cpumask_test_and_set_cpu - atomically test and set a cpu in a cpumask
 * @cpu: cpu number (< nr_cpu_ids)
 * @cpumask: the cpumask pointer
 *
 * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
 *
 * test_and_set_bit wrapper for cpumasks.
 */
static inline int cpumask_test_and_set_cpu(int cpu, struct cpumask *cpumask)
{
        return test_and_set_bit(cpumask_check(cpu), cpumask_bits(cpumask));
}

/**
 * cpumask_test_and_clear_cpu - atomically test and clear a cpu in a cpumask
 * @cpu: cpu number (< nr_cpu_ids)
 * @cpumask: the cpumask pointer
 *
 * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
 *
 * test_and_clear_bit wrapper for cpumasks.
 */
static inline int cpumask_test_and_clear_cpu(int cpu, struct cpumask *cpumask)
{
        return test_and_clear_bit(cpumask_check(cpu), cpumask_bits(cpumask));
}

/**
 * cpumask_setall - set all cpus (< nr_cpu_ids) in a cpumask
 * @dstp: the cpumask pointer
 */
static inline void cpumask_setall(struct cpumask *dstp)
{
        bitmap_fill(cpumask_bits(dstp), nr_cpumask_bits);
}

/**
 * cpumask_clear - clear all cpus (< nr_cpu_ids) in a cpumask
 * @dstp: the cpumask pointer
 */
static inline void cpumask_clear(struct cpumask *dstp)
{
        bitmap_zero(cpumask_bits(dstp), nr_cpumask_bits);
}

/**
 * cpumask_and - *dstp = *src1p & *src2p
 * @dstp: the cpumask result
 * @src1p: the first input
 * @src2p: the second input
 *
 * If *@dstp is empty, returns 0, else returns 1
 */
static inline int cpumask_and(struct cpumask *dstp,
                               const struct cpumask *src1p,
                               const struct cpumask *src2p)
{
        return bitmap_and(cpumask_bits(dstp), cpumask_bits(src1p),
                                       cpumask_bits(src2p), nr_cpumask_bits);
}

/**
 * cpumask_or - *dstp = *src1p | *src2p
 * @dstp: the cpumask result
 * @src1p: the first input
 * @src2p: the second input
 */
static inline void cpumask_or(struct cpumask *dstp, const struct cpumask *src1p,
                              const struct cpumask *src2p)
{
        bitmap_or(cpumask_bits(dstp), cpumask_bits(src1p),
                                      cpumask_bits(src2p), nr_cpumask_bits);
}

/**
 * cpumask_xor - *dstp = *src1p ^ *src2p
 * @dstp: the cpumask result
 * @src1p: the first input
 * @src2p: the second input
 */
static inline void cpumask_xor(struct cpumask *dstp,
                               const struct cpumask *src1p,
                               const struct cpumask *src2p)
{
        bitmap_xor(cpumask_bits(dstp), cpumask_bits(src1p),
                                       cpumask_bits(src2p), nr_cpumask_bits);
}

/**
 * cpumask_andnot - *dstp = *src1p & ~*src2p
 * @dstp: the cpumask result
 * @src1p: the first input
 * @src2p: the second input
 *
 * If *@dstp is empty, returns 0, else returns 1
 */
static inline int cpumask_andnot(struct cpumask *dstp,
                                  const struct cpumask *src1p,
                                  const struct cpumask *src2p)
{
        return bitmap_andnot(cpumask_bits(dstp), cpumask_bits(src1p),
                                          cpumask_bits(src2p), nr_cpumask_bits);
}

/**
 * cpumask_complement - *dstp = ~*srcp
 * @dstp: the cpumask result
 * @srcp: the input to invert
 */
static inline void cpumask_complement(struct cpumask *dstp,
                                      const struct cpumask *srcp)
{
        bitmap_complement(cpumask_bits(dstp), cpumask_bits(srcp),
                                              nr_cpumask_bits);
}

/**
 * cpumask_equal - *src1p == *src2p
 * @src1p: the first input
 * @src2p: the second input
 */
static inline bool cpumask_equal(const struct cpumask *src1p,
                                const struct cpumask *src2p)
{
        return bitmap_equal(cpumask_bits(src1p), cpumask_bits(src2p),
                                                 nr_cpumask_bits);
}

/**
 * cpumask_intersects - (*src1p & *src2p) != 0
 * @src1p: the first input
 * @src2p: the second input
 */
static inline bool cpumask_intersects(const struct cpumask *src1p,
                                     const struct cpumask *src2p)
{
        return bitmap_intersects(cpumask_bits(src1p), cpumask_bits(src2p),
                                                      nr_cpumask_bits);
}

/**
 * cpumask_subset - (*src1p & ~*src2p) == 0
 * @src1p: the first input
 * @src2p: the second input
 *
 * Returns 1 if *@src1p is a subset of *@src2p, else returns 0
 */
static inline int cpumask_subset(const struct cpumask *src1p,
                                 const struct cpumask *src2p)
{
        return bitmap_subset(cpumask_bits(src1p), cpumask_bits(src2p),
                                                  nr_cpumask_bits);
}

/**
 * cpumask_empty - *srcp == 0
 * @srcp: the cpumask to that all cpus < nr_cpu_ids are clear.
 */
static inline bool cpumask_empty(const struct cpumask *srcp)
{
        return bitmap_empty(cpumask_bits(srcp), nr_cpumask_bits);
}

/**
 * cpumask_full - *srcp == 0xFFFFFFFF...
 * @srcp: the cpumask to that all cpus < nr_cpu_ids are set.
 */
static inline bool cpumask_full(const struct cpumask *srcp)
{
        return bitmap_full(cpumask_bits(srcp), nr_cpumask_bits);
}

/**
 * cpumask_weight - Count of bits in *srcp
 * @srcp: the cpumask to count bits (< nr_cpu_ids) in.
 */
static inline unsigned int cpumask_weight(const struct cpumask *srcp)
{
        return bitmap_weight(cpumask_bits(srcp), nr_cpumask_bits);
}

/**
 * cpumask_shift_right - *dstp = *srcp >> n
 * @dstp: the cpumask result
 * @srcp: the input to shift
 * @n: the number of bits to shift by
 */
static inline void cpumask_shift_right(struct cpumask *dstp,
                                       const struct cpumask *srcp, int n)
{
        bitmap_shift_right(cpumask_bits(dstp), cpumask_bits(srcp), n,
                                               nr_cpumask_bits);
}

/**
 * cpumask_shift_left - *dstp = *srcp << n
 * @dstp: the cpumask result
 * @srcp: the input to shift
 * @n: the number of bits to shift by
 */
static inline void cpumask_shift_left(struct cpumask *dstp,
                                      const struct cpumask *srcp, int n)
{
        bitmap_shift_left(cpumask_bits(dstp), cpumask_bits(srcp), n,
                                              nr_cpumask_bits);
}

/**
 * cpumask_copy - *dstp = *srcp
 * @dstp: the result
 * @srcp: the input cpumask
 */
static inline void cpumask_copy(struct cpumask *dstp,
                                const struct cpumask *srcp)
{
        bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), nr_cpumask_bits);
}

/**
 * cpumask_any - pick a "random" cpu from *srcp
 * @srcp: the input cpumask
 *
 * Returns >= nr_cpu_ids if no cpus set.
 */
#define cpumask_any(srcp) cpumask_first(srcp)

/**
 * cpumask_first_and - return the first cpu from *srcp1 & *srcp2
 * @src1p: the first input
 * @src2p: the second input
 *
 * Returns >= nr_cpu_ids if no cpus set in both.  See also cpumask_next_and().
 */
#define cpumask_first_and(src1p, src2p) cpumask_next_and(-1, (src1p), (src2p))

/**
 * cpumask_any_and - pick a "random" cpu from *mask1 & *mask2
 * @mask1: the first input cpumask
 * @mask2: the second input cpumask
 *
 * Returns >= nr_cpu_ids if no cpus set.
 */
#define cpumask_any_and(mask1, mask2) cpumask_first_and((mask1), (mask2))

/**
 * cpumask_of - the cpumask containing just a given cpu
 * @cpu: the cpu (<= nr_cpu_ids)
 */
#define cpumask_of(cpu) (get_cpu_mask(cpu))

/**
 * cpumask_scnprintf - print a cpumask into a string as comma-separated hex
 * @buf: the buffer to sprintf into
 * @len: the length of the buffer
 * @srcp: the cpumask to print
 *
 * If len is zero, returns zero.  Otherwise returns the length of the
 * (nul-terminated) @buf string.
 */
static inline int cpumask_scnprintf(char *buf, int len,
                                    const struct cpumask *srcp)
{
        return bitmap_scnprintf(buf, len, cpumask_bits(srcp), nr_cpumask_bits);
}

/**
 * cpumask_parse_user - extract a cpumask from a user string
 * @buf: the buffer to extract from
 * @len: the length of the buffer
 * @dstp: the cpumask to set.
 *
 * Returns -errno, or 0 for success.
 */
static inline int cpumask_parse_user(const char __user *buf, int len,
                                     struct cpumask *dstp)
{
        return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpumask_bits);
}

/**
 * cpumask_parselist_user - extract a cpumask from a user string
 * @buf: the buffer to extract from
 * @len: the length of the buffer
 * @dstp: the cpumask to set.
 *
 * Returns -errno, or 0 for success.
 */
static inline int cpumask_parselist_user(const char __user *buf, int len,
                                     struct cpumask *dstp)
{
        return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
                                                        nr_cpumask_bits);
}

/**
 * cpulist_scnprintf - print a cpumask into a string as comma-separated list
 * @buf: the buffer to sprintf into
 * @len: the length of the buffer
 * @srcp: the cpumask to print
 *
 * If len is zero, returns zero.  Otherwise returns the length of the
 * (nul-terminated) @buf string.
 */
static inline int cpulist_scnprintf(char *buf, int len,
                                    const struct cpumask *srcp)
{
        return bitmap_scnlistprintf(buf, len, cpumask_bits(srcp),
                                    nr_cpumask_bits);
}

/**
 * cpumask_parse - extract a cpumask from from a string
 * @buf: the buffer to extract from
 * @dstp: the cpumask to set.
 *
 * Returns -errno, or 0 for success.
 */
static inline int cpumask_parse(const char *buf, struct cpumask *dstp)
{
        char *nl = strchr(buf, '\n');
        unsigned int len = nl ? (unsigned int)(nl - buf) : strlen(buf);

        return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpumask_bits);
}

/**
 * cpulist_parse - extract a cpumask from a user string of ranges
 * @buf: the buffer to extract from
 * @dstp: the cpumask to set.
 *
 * Returns -errno, or 0 for success.
 */
static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
{
        return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpumask_bits);
}

/**
 * cpumask_size - size to allocate for a 'struct cpumask' in bytes
 *
 * This will eventually be a runtime variable, depending on nr_cpu_ids.
 */
static inline size_t cpumask_size(void)
{
        /* FIXME: Once all cpumask assignments are eliminated, this
         * can be nr_cpumask_bits */
        return BITS_TO_LONGS(NR_CPUS) * sizeof(long);
}

/*
 * cpumask_var_t: struct cpumask for stack usage.
 *
 * Oh, the wicked games we play!  In order to make kernel coding a
 * little more difficult, we typedef cpumask_var_t to an array or a
 * pointer: doing &mask on an array is a noop, so it still works.
 *
 * ie.
 *      cpumask_var_t tmpmask;
 *      if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
 *              return -ENOMEM;
 *
 *        ... use 'tmpmask' like a normal struct cpumask * ...
 *
 *      free_cpumask_var(tmpmask);
 *
 *
 * However, one notable exception is there. alloc_cpumask_var() allocates
 * only nr_cpumask_bits bits (in the other hand, real cpumask_t always has
 * NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t.
 *
 *      cpumask_var_t tmpmask;
 *      if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
 *              return -ENOMEM;
 *
 *      var = *tmpmask;
 *
 * This code makes NR_CPUS length memcopy and brings to a memory corruption.
 * cpumask_copy() provide safe copy functionality.
 *
 * Note that there is another evil here: If you define a cpumask_var_t
 * as a percpu variable then the way to obtain the address of the cpumask
 * structure differently influences what this_cpu_* operation needs to be
 * used. Please use this_cpu_cpumask_var_t in those cases. The direct use
 * of this_cpu_ptr() or this_cpu_read() will lead to failures when the
 * other type of cpumask_var_t implementation is configured.
 */
#ifdef CONFIG_CPUMASK_OFFSTACK
typedef struct cpumask *cpumask_var_t;

#define this_cpu_cpumask_var_ptr(x) this_cpu_read(x)

bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
void alloc_bootmem_cpumask_var(cpumask_var_t *mask);
void free_cpumask_var(cpumask_var_t mask);
void free_bootmem_cpumask_var(cpumask_var_t mask);

#else
typedef struct cpumask cpumask_var_t[1];

#define this_cpu_cpumask_var_ptr(x) this_cpu_ptr(x)

static inline bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
{
        return true;
}

static inline bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
                                          int node)
{
        return true;
}

static inline bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
{
        cpumask_clear(*mask);
        return true;
}

static inline bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
                                          int node)
{
        cpumask_clear(*mask);
        return true;
}

static inline void alloc_bootmem_cpumask_var(cpumask_var_t *mask)
{
}

static inline void free_cpumask_var(cpumask_var_t mask)
{
}

static inline void free_bootmem_cpumask_var(cpumask_var_t mask)
{
}
#endif /* CONFIG_CPUMASK_OFFSTACK */

/* It's common to want to use cpu_all_mask in struct member initializers,
 * so it has to refer to an address rather than a pointer. */
extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
#define cpu_all_mask to_cpumask(cpu_all_bits)

/* First bits of cpu_bit_bitmap are in fact unset. */
#define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])

#define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
#define for_each_online_cpu(cpu)   for_each_cpu((cpu), cpu_online_mask)
#define for_each_present_cpu(cpu)  for_each_cpu((cpu), cpu_present_mask)

/* Wrappers for arch boot code to manipulate normally-constant masks */
void set_cpu_possible(unsigned int cpu, bool possible);
void set_cpu_present(unsigned int cpu, bool present);
void set_cpu_online(unsigned int cpu, bool online);
void set_cpu_active(unsigned int cpu, bool active);
void init_cpu_present(const struct cpumask *src);
void init_cpu_possible(const struct cpumask *src);
void init_cpu_online(const struct cpumask *src);

/**
 * to_cpumask - convert an NR_CPUS bitmap to a struct cpumask *
 * @bitmap: the bitmap
 *
 * There are a few places where cpumask_var_t isn't appropriate and
 * static cpumasks must be used (eg. very early boot), yet we don't
 * expose the definition of 'struct cpumask'.
 *
 * This does the conversion, and can be used as a constant initializer.
 */
#define to_cpumask(bitmap)                                              \
        ((struct cpumask *)(1 ? (bitmap)                                \
                            : (void *)sizeof(__check_is_bitmap(bitmap))))

static inline int __check_is_bitmap(const unsigned long *bitmap)
{
        return 1;
}

/*
 * Special-case data structure for "single bit set only" constant CPU masks.
 *
 * We pre-generate all the 64 (or 32) possible bit positions, with enough
 * padding to the left and the right, and return the constant pointer
 * appropriately offset.
 */
extern const unsigned long
        cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)];

static inline const struct cpumask *get_cpu_mask(unsigned int cpu)
{
        const unsigned long *p = cpu_bit_bitmap[1 + cpu % BITS_PER_LONG];
        p -= cpu / BITS_PER_LONG;
        return to_cpumask(p);
}

#define cpu_is_offline(cpu)     unlikely(!cpu_online(cpu))

#if NR_CPUS <= BITS_PER_LONG
#define CPU_BITS_ALL                                            \
{                                                               \
        [BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD \
}

#else /* NR_CPUS > BITS_PER_LONG */

#define CPU_BITS_ALL                                            \
{                                                               \
        [0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,                \
        [BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD         \
}
#endif /* NR_CPUS > BITS_PER_LONG */

/*
 *
 * From here down, all obsolete.  Use cpumask_ variants!
 *
 */
#ifndef CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS
#define cpumask_of_cpu(cpu) (*get_cpu_mask(cpu))

#define CPU_MASK_LAST_WORD BITMAP_LAST_WORD_MASK(NR_CPUS)

#if NR_CPUS <= BITS_PER_LONG

#define CPU_MASK_ALL                                                    \
(cpumask_t) { {                                                         \
        [BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD                 \
} }

#else

#define CPU_MASK_ALL                                                    \
(cpumask_t) { {                                                         \
        [0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,                        \
        [BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD                 \
} }

#endif

#define CPU_MASK_NONE                                                   \
(cpumask_t) { {                                                         \
        [0 ... BITS_TO_LONGS(NR_CPUS)-1] =  0UL                         \
} }

#define CPU_MASK_CPU0                                                   \
(cpumask_t) { {                                                         \
        [0] =  1UL                                                      \
} }

#if NR_CPUS == 1
#define first_cpu(src)          ({ (void)(src); 0; })
#define next_cpu(n, src)        ({ (void)(src); 1; })
#define any_online_cpu(mask)    0
#define for_each_cpu_mask(cpu, mask)    \
        for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
#else /* NR_CPUS > 1 */
int __first_cpu(const cpumask_t *srcp);
int __next_cpu(int n, const cpumask_t *srcp);

#define first_cpu(src)          __first_cpu(&(src))
#define next_cpu(n, src)        __next_cpu((n), &(src))
#define any_online_cpu(mask) cpumask_any_and(&mask, cpu_online_mask)
#define for_each_cpu_mask(cpu, mask)                    \
        for ((cpu) = -1;                                \
                (cpu) = next_cpu((cpu), (mask)),        \
                (cpu) < NR_CPUS; )
#endif /* SMP */

#if NR_CPUS <= 64

#define for_each_cpu_mask_nr(cpu, mask) for_each_cpu_mask(cpu, mask)

#else /* NR_CPUS > 64 */

int __next_cpu_nr(int n, const cpumask_t *srcp);
#define for_each_cpu_mask_nr(cpu, mask)                 \
        for ((cpu) = -1;                                \
                (cpu) = __next_cpu_nr((cpu), &(mask)),  \
                (cpu) < nr_cpu_ids; )

#endif /* NR_CPUS > 64 */

#define cpus_addr(src) ((src).bits)

#define cpu_set(cpu, dst) __cpu_set((cpu), &(dst))
static inline void __cpu_set(int cpu, volatile cpumask_t *dstp)
{
        set_bit(cpu, dstp->bits);
}

#define cpu_clear(cpu, dst) __cpu_clear((cpu), &(dst))
static inline void __cpu_clear(int cpu, volatile cpumask_t *dstp)
{
        clear_bit(cpu, dstp->bits);
}

#define cpus_setall(dst) __cpus_setall(&(dst), NR_CPUS)
static inline void __cpus_setall(cpumask_t *dstp, int nbits)
{
        bitmap_fill(dstp->bits, nbits);
}

#define cpus_clear(dst) __cpus_clear(&(dst), NR_CPUS)
static inline void __cpus_clear(cpumask_t *dstp, int nbits)
{
        bitmap_zero(dstp->bits, nbits);
}

/* No static inline type checking - see Subtlety (1) above. */
#define cpu_isset(cpu, cpumask) test_bit((cpu), (cpumask).bits)

#define cpu_test_and_set(cpu, cpumask) __cpu_test_and_set((cpu), &(cpumask))
static inline int __cpu_test_and_set(int cpu, cpumask_t *addr)
{
        return test_and_set_bit(cpu, addr->bits);
}

#define cpus_and(dst, src1, src2) __cpus_and(&(dst), &(src1), &(src2), NR_CPUS)
static inline int __cpus_and(cpumask_t *dstp, const cpumask_t *src1p,
                                        const cpumask_t *src2p, int nbits)
{
        return bitmap_and(dstp->bits, src1p->bits, src2p->bits, nbits);
}

#define cpus_or(dst, src1, src2) __cpus_or(&(dst), &(src1), &(src2), NR_CPUS)
static inline void __cpus_or(cpumask_t *dstp, const cpumask_t *src1p,
                                        const cpumask_t *src2p, int nbits)
{
        bitmap_or(dstp->bits, src1p->bits, src2p->bits, nbits);
}

#define cpus_xor(dst, src1, src2) __cpus_xor(&(dst), &(src1), &(src2), NR_CPUS)
static inline void __cpus_xor(cpumask_t *dstp, const cpumask_t *src1p,
                                        const cpumask_t *src2p, int nbits)
{
        bitmap_xor(dstp->bits, src1p->bits, src2p->bits, nbits);
}

#define cpus_andnot(dst, src1, src2) \
                                __cpus_andnot(&(dst), &(src1), &(src2), NR_CPUS)
static inline int __cpus_andnot(cpumask_t *dstp, const cpumask_t *src1p,
                                        const cpumask_t *src2p, int nbits)
{
        return bitmap_andnot(dstp->bits, src1p->bits, src2p->bits, nbits);
}

#define cpus_equal(src1, src2) __cpus_equal(&(src1), &(src2), NR_CPUS)
static inline int __cpus_equal(const cpumask_t *src1p,
                                        const cpumask_t *src2p, int nbits)
{
        return bitmap_equal(src1p->bits, src2p->bits, nbits);
}

#define cpus_intersects(src1, src2) __cpus_intersects(&(src1), &(src2), NR_CPUS)
static inline int __cpus_intersects(const cpumask_t *src1p,
                                        const cpumask_t *src2p, int nbits)
{
        return bitmap_intersects(src1p->bits, src2p->bits, nbits);
}

#define cpus_subset(src1, src2) __cpus_subset(&(src1), &(src2), NR_CPUS)
static inline int __cpus_subset(const cpumask_t *src1p,
                                        const cpumask_t *src2p, int nbits)
{
        return bitmap_subset(src1p->bits, src2p->bits, nbits);
}

#define cpus_empty(src) __cpus_empty(&(src), NR_CPUS)
static inline int __cpus_empty(const cpumask_t *srcp, int nbits)
{
        return bitmap_empty(srcp->bits, nbits);
}

#define cpus_weight(cpumask) __cpus_weight(&(cpumask), NR_CPUS)
static inline int __cpus_weight(const cpumask_t *srcp, int nbits)
{
        return bitmap_weight(srcp->bits, nbits);
}

#define cpus_shift_left(dst, src, n) \
                        __cpus_shift_left(&(dst), &(src), (n), NR_CPUS)
static inline void __cpus_shift_left(cpumask_t *dstp,
                                        const cpumask_t *srcp, int n, int nbits)
{
        bitmap_shift_left(dstp->bits, srcp->bits, n, nbits);
}
#endif /* !CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS */

#endif /* __LINUX_CPUMASK_H */