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