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