Root/lib/cpumask.c

1#include <linux/slab.h>
2#include <linux/kernel.h>
3#include <linux/bitops.h>
4#include <linux/cpumask.h>
5#include <linux/export.h>
6#include <linux/bootmem.h>
7
8int __first_cpu(const cpumask_t *srcp)
9{
10    return min_t(int, NR_CPUS, find_first_bit(srcp->bits, NR_CPUS));
11}
12EXPORT_SYMBOL(__first_cpu);
13
14int __next_cpu(int n, const cpumask_t *srcp)
15{
16    return min_t(int, NR_CPUS, find_next_bit(srcp->bits, NR_CPUS, n+1));
17}
18EXPORT_SYMBOL(__next_cpu);
19
20#if NR_CPUS > 64
21int __next_cpu_nr(int n, const cpumask_t *srcp)
22{
23    return min_t(int, nr_cpu_ids,
24                find_next_bit(srcp->bits, nr_cpu_ids, n+1));
25}
26EXPORT_SYMBOL(__next_cpu_nr);
27#endif
28
29/**
30 * cpumask_next_and - get the next cpu in *src1p & *src2p
31 * @n: the cpu prior to the place to search (ie. return will be > @n)
32 * @src1p: the first cpumask pointer
33 * @src2p: the second cpumask pointer
34 *
35 * Returns >= nr_cpu_ids if no further cpus set in both.
36 */
37int cpumask_next_and(int n, const struct cpumask *src1p,
38             const struct cpumask *src2p)
39{
40    while ((n = cpumask_next(n, src1p)) < nr_cpu_ids)
41        if (cpumask_test_cpu(n, src2p))
42            break;
43    return n;
44}
45EXPORT_SYMBOL(cpumask_next_and);
46
47/**
48 * cpumask_any_but - return a "random" in a cpumask, but not this one.
49 * @mask: the cpumask to search
50 * @cpu: the cpu to ignore.
51 *
52 * Often used to find any cpu but smp_processor_id() in a mask.
53 * Returns >= nr_cpu_ids if no cpus set.
54 */
55int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
56{
57    unsigned int i;
58
59    cpumask_check(cpu);
60    for_each_cpu(i, mask)
61        if (i != cpu)
62            break;
63    return i;
64}
65
66/* These are not inline because of header tangles. */
67#ifdef CONFIG_CPUMASK_OFFSTACK
68/**
69 * alloc_cpumask_var_node - allocate a struct cpumask on a given node
70 * @mask: pointer to cpumask_var_t where the cpumask is returned
71 * @flags: GFP_ flags
72 *
73 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
74 * a nop returning a constant 1 (in <linux/cpumask.h>)
75 * Returns TRUE if memory allocation succeeded, FALSE otherwise.
76 *
77 * In addition, mask will be NULL if this fails. Note that gcc is
78 * usually smart enough to know that mask can never be NULL if
79 * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
80 * too.
81 */
82bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
83{
84    *mask = kmalloc_node(cpumask_size(), flags, node);
85
86#ifdef CONFIG_DEBUG_PER_CPU_MAPS
87    if (!*mask) {
88        printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
89        dump_stack();
90    }
91#endif
92    /* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */
93    if (*mask) {
94        unsigned char *ptr = (unsigned char *)cpumask_bits(*mask);
95        unsigned int tail;
96        tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long);
97        memset(ptr + cpumask_size() - tail, 0, tail);
98    }
99
100    return *mask != NULL;
101}
102EXPORT_SYMBOL(alloc_cpumask_var_node);
103
104bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
105{
106    return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
107}
108EXPORT_SYMBOL(zalloc_cpumask_var_node);
109
110/**
111 * alloc_cpumask_var - allocate a struct cpumask
112 * @mask: pointer to cpumask_var_t where the cpumask is returned
113 * @flags: GFP_ flags
114 *
115 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
116 * a nop returning a constant 1 (in <linux/cpumask.h>).
117 *
118 * See alloc_cpumask_var_node.
119 */
120bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
121{
122    return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
123}
124EXPORT_SYMBOL(alloc_cpumask_var);
125
126bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
127{
128    return alloc_cpumask_var(mask, flags | __GFP_ZERO);
129}
130EXPORT_SYMBOL(zalloc_cpumask_var);
131
132/**
133 * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
134 * @mask: pointer to cpumask_var_t where the cpumask is returned
135 *
136 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
137 * a nop (in <linux/cpumask.h>).
138 * Either returns an allocated (zero-filled) cpumask, or causes the
139 * system to panic.
140 */
141void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
142{
143    *mask = alloc_bootmem(cpumask_size());
144}
145
146/**
147 * free_cpumask_var - frees memory allocated for a struct cpumask.
148 * @mask: cpumask to free
149 *
150 * This is safe on a NULL mask.
151 */
152void free_cpumask_var(cpumask_var_t mask)
153{
154    kfree(mask);
155}
156EXPORT_SYMBOL(free_cpumask_var);
157
158/**
159 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
160 * @mask: cpumask to free
161 */
162void __init free_bootmem_cpumask_var(cpumask_var_t mask)
163{
164    free_bootmem(__pa(mask), cpumask_size());
165}
166#endif
167

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