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b2441318 1// SPDX-License-Identifier: GPL-2.0
5a0e3ad6 2#include <linux/slab.h>
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3#include <linux/kernel.h>
4#include <linux/bitops.h>
5#include <linux/cpumask.h>
8bc3bcc9 6#include <linux/export.h>
57c8a661 7#include <linux/memblock.h>
98fa15f3 8#include <linux/numa.h>
1abdfe70 9#include <linux/sched/isolation.h>
ccb46000 10
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11/**
12 * cpumask_next - get the next cpu in a cpumask
13 * @n: the cpu prior to the place to search (ie. return will be > @n)
14 * @srcp: the cpumask pointer
15 *
16 * Returns >= nr_cpu_ids if no further cpus set.
17 */
18unsigned int cpumask_next(int n, const struct cpumask *srcp)
19{
20 /* -1 is a legal arg here. */
21 if (n != -1)
22 cpumask_check(n);
23 return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1);
24}
25EXPORT_SYMBOL(cpumask_next);
26
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27/**
28 * cpumask_next_and - get the next cpu in *src1p & *src2p
29 * @n: the cpu prior to the place to search (ie. return will be > @n)
30 * @src1p: the first cpumask pointer
31 * @src2p: the second cpumask pointer
32 *
33 * Returns >= nr_cpu_ids if no further cpus set in both.
34 */
35int cpumask_next_and(int n, const struct cpumask *src1p,
36 const struct cpumask *src2p)
37{
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CC
38 /* -1 is a legal arg here. */
39 if (n != -1)
40 cpumask_check(n);
41 return find_next_and_bit(cpumask_bits(src1p), cpumask_bits(src2p),
42 nr_cpumask_bits, n + 1);
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43}
44EXPORT_SYMBOL(cpumask_next_and);
45
46/**
47 * cpumask_any_but - return a "random" in a cpumask, but not this one.
48 * @mask: the cpumask to search
49 * @cpu: the cpu to ignore.
50 *
51 * Often used to find any cpu but smp_processor_id() in a mask.
52 * Returns >= nr_cpu_ids if no cpus set.
53 */
54int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
55{
56 unsigned int i;
57
984f2f37 58 cpumask_check(cpu);
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59 for_each_cpu(i, mask)
60 if (i != cpu)
61 break;
62 return i;
63}
3712bba1 64EXPORT_SYMBOL(cpumask_any_but);
2d3854a3 65
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66/**
67 * cpumask_next_wrap - helper to implement for_each_cpu_wrap
68 * @n: the cpu prior to the place to search
69 * @mask: the cpumask pointer
70 * @start: the start point of the iteration
71 * @wrap: assume @n crossing @start terminates the iteration
72 *
73 * Returns >= nr_cpu_ids on completion
74 *
75 * Note: the @wrap argument is required for the start condition when
76 * we cannot assume @start is set in @mask.
77 */
78int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
79{
80 int next;
81
82again:
83 next = cpumask_next(n, mask);
84
85 if (wrap && n < start && next >= start) {
86 return nr_cpumask_bits;
87
88 } else if (next >= nr_cpumask_bits) {
89 wrap = true;
90 n = -1;
91 goto again;
92 }
93
94 return next;
95}
96EXPORT_SYMBOL(cpumask_next_wrap);
97
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98/* These are not inline because of header tangles. */
99#ifdef CONFIG_CPUMASK_OFFSTACK
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100/**
101 * alloc_cpumask_var_node - allocate a struct cpumask on a given node
102 * @mask: pointer to cpumask_var_t where the cpumask is returned
103 * @flags: GFP_ flags
104 *
105 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
106 * a nop returning a constant 1 (in <linux/cpumask.h>)
107 * Returns TRUE if memory allocation succeeded, FALSE otherwise.
108 *
109 * In addition, mask will be NULL if this fails. Note that gcc is
110 * usually smart enough to know that mask can never be NULL if
111 * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
112 * too.
113 */
7b4967c5 114bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
2d3854a3 115{
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116 *mask = kmalloc_node(cpumask_size(), flags, node);
117
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118#ifdef CONFIG_DEBUG_PER_CPU_MAPS
119 if (!*mask) {
120 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
121 dump_stack();
122 }
123#endif
2a530080 124
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125 return *mask != NULL;
126}
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127EXPORT_SYMBOL(alloc_cpumask_var_node);
128
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129bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
130{
131 return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
132}
133EXPORT_SYMBOL(zalloc_cpumask_var_node);
134
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135/**
136 * alloc_cpumask_var - allocate a struct cpumask
137 * @mask: pointer to cpumask_var_t where the cpumask is returned
138 * @flags: GFP_ flags
139 *
140 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
141 * a nop returning a constant 1 (in <linux/cpumask.h>).
142 *
143 * See alloc_cpumask_var_node.
144 */
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145bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
146{
37e7b5f1 147 return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
7b4967c5 148}
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149EXPORT_SYMBOL(alloc_cpumask_var);
150
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151bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
152{
153 return alloc_cpumask_var(mask, flags | __GFP_ZERO);
154}
155EXPORT_SYMBOL(zalloc_cpumask_var);
156
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157/**
158 * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
159 * @mask: pointer to cpumask_var_t where the cpumask is returned
160 *
161 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
e9690a6e 162 * a nop (in <linux/cpumask.h>).
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163 * Either returns an allocated (zero-filled) cpumask, or causes the
164 * system to panic.
165 */
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166void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
167{
7e1c4e27 168 *mask = memblock_alloc(cpumask_size(), SMP_CACHE_BYTES);
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169 if (!*mask)
170 panic("%s: Failed to allocate %u bytes\n", __func__,
171 cpumask_size());
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172}
173
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174/**
175 * free_cpumask_var - frees memory allocated for a struct cpumask.
176 * @mask: cpumask to free
177 *
178 * This is safe on a NULL mask.
179 */
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180void free_cpumask_var(cpumask_var_t mask)
181{
182 kfree(mask);
183}
184EXPORT_SYMBOL(free_cpumask_var);
cd83e42c 185
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186/**
187 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
188 * @mask: cpumask to free
189 */
984f2f37 190void __init free_bootmem_cpumask_var(cpumask_var_t mask)
cd83e42c 191{
c1529500 192 memblock_free_early(__pa(mask), cpumask_size());
cd83e42c 193}
2d3854a3 194#endif
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195
196/**
f36963c9 197 * cpumask_local_spread - select the i'th cpu with local numa cpu's first
da91309e 198 * @i: index number
f36963c9 199 * @node: local numa_node
da91309e 200 *
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201 * This function selects an online CPU according to a numa aware policy;
202 * local cpus are returned first, followed by non-local ones, then it
203 * wraps around.
da91309e 204 *
f36963c9 205 * It's not very efficient, but useful for setup.
da91309e 206 */
f36963c9 207unsigned int cpumask_local_spread(unsigned int i, int node)
da91309e 208{
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209 int cpu, hk_flags;
210 const struct cpumask *mask;
da91309e 211
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212 hk_flags = HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ;
213 mask = housekeeping_cpumask(hk_flags);
f36963c9 214 /* Wrap: we always want a cpu. */
1abdfe70 215 i %= cpumask_weight(mask);
da91309e 216
98fa15f3 217 if (node == NUMA_NO_NODE) {
1abdfe70 218 for_each_cpu(cpu, mask) {
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219 if (i-- == 0)
220 return cpu;
1abdfe70 221 }
da91309e 222 } else {
f36963c9 223 /* NUMA first. */
1abdfe70 224 for_each_cpu_and(cpu, cpumask_of_node(node), mask) {
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225 if (i-- == 0)
226 return cpu;
1abdfe70 227 }
f36963c9 228
1abdfe70 229 for_each_cpu(cpu, mask) {
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230 /* Skip NUMA nodes, done above. */
231 if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
232 continue;
233
234 if (i-- == 0)
235 return cpu;
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AV
236 }
237 }
f36963c9 238 BUG();
da91309e 239}
f36963c9 240EXPORT_SYMBOL(cpumask_local_spread);
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PT
241
242static DEFINE_PER_CPU(int, distribute_cpu_mask_prev);
243
244/**
245 * Returns an arbitrary cpu within srcp1 & srcp2.
246 *
247 * Iterated calls using the same srcp1 and srcp2 will be distributed within
248 * their intersection.
249 *
250 * Returns >= nr_cpu_ids if the intersection is empty.
251 */
252int cpumask_any_and_distribute(const struct cpumask *src1p,
253 const struct cpumask *src2p)
254{
255 int next, prev;
256
257 /* NOTE: our first selection will skip 0. */
258 prev = __this_cpu_read(distribute_cpu_mask_prev);
259
260 next = cpumask_next_and(prev, src1p, src2p);
261 if (next >= nr_cpu_ids)
262 next = cpumask_first_and(src1p, src2p);
263
264 if (next < nr_cpu_ids)
265 __this_cpu_write(distribute_cpu_mask_prev, next);
266
267 return next;
268}
269EXPORT_SYMBOL(cpumask_any_and_distribute);