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 #include <linux/sched/isolation.h>
10
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 */
cpumask_next(int n,const struct cpumask * srcp)18 unsigned 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 }
25 EXPORT_SYMBOL(cpumask_next);
26
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 */
cpumask_next_and(int n,const struct cpumask * src1p,const struct cpumask * src2p)35 int cpumask_next_and(int n, const struct cpumask *src1p,
36 const struct cpumask *src2p)
37 {
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);
43 }
44 EXPORT_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 */
cpumask_any_but(const struct cpumask * mask,unsigned int cpu)54 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
55 {
56 unsigned int i;
57
58 cpumask_check(cpu);
59 for_each_cpu(i, mask)
60 if (i != cpu)
61 break;
62 return i;
63 }
64 EXPORT_SYMBOL(cpumask_any_but);
65
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 */
cpumask_next_wrap(int n,const struct cpumask * mask,int start,bool wrap)78 int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
79 {
80 int next;
81
82 again:
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 }
96 EXPORT_SYMBOL(cpumask_next_wrap);
97
98 /* These are not inline because of header tangles. */
99 #ifdef CONFIG_CPUMASK_OFFSTACK
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 */
alloc_cpumask_var_node(cpumask_var_t * mask,gfp_t flags,int node)114 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
115 {
116 *mask = kmalloc_node(cpumask_size(), flags, node);
117
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
124
125 return *mask != NULL;
126 }
127 EXPORT_SYMBOL(alloc_cpumask_var_node);
128
zalloc_cpumask_var_node(cpumask_var_t * mask,gfp_t flags,int node)129 bool 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 }
133 EXPORT_SYMBOL(zalloc_cpumask_var_node);
134
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 */
alloc_cpumask_var(cpumask_var_t * mask,gfp_t flags)145 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
146 {
147 return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
148 }
149 EXPORT_SYMBOL(alloc_cpumask_var);
150
zalloc_cpumask_var(cpumask_var_t * mask,gfp_t flags)151 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
152 {
153 return alloc_cpumask_var(mask, flags | __GFP_ZERO);
154 }
155 EXPORT_SYMBOL(zalloc_cpumask_var);
156
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
162 * a nop (in <linux/cpumask.h>).
163 * Either returns an allocated (zero-filled) cpumask, or causes the
164 * system to panic.
165 */
alloc_bootmem_cpumask_var(cpumask_var_t * mask)166 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
167 {
168 *mask = memblock_alloc(cpumask_size(), SMP_CACHE_BYTES);
169 if (!*mask)
170 panic("%s: Failed to allocate %u bytes\n", __func__,
171 cpumask_size());
172 }
173
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 */
free_cpumask_var(cpumask_var_t mask)180 void free_cpumask_var(cpumask_var_t mask)
181 {
182 kfree(mask);
183 }
184 EXPORT_SYMBOL(free_cpumask_var);
185
186 /**
187 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
188 * @mask: cpumask to free
189 */
free_bootmem_cpumask_var(cpumask_var_t mask)190 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
191 {
192 memblock_free_early(__pa(mask), cpumask_size());
193 }
194 #endif
195
196 /**
197 * cpumask_local_spread - select the i'th cpu with local numa cpu's first
198 * @i: index number
199 * @node: local numa_node
200 *
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.
204 *
205 * It's not very efficient, but useful for setup.
206 */
cpumask_local_spread(unsigned int i,int node)207 unsigned int cpumask_local_spread(unsigned int i, int node)
208 {
209 int cpu, hk_flags;
210 const struct cpumask *mask;
211
212 hk_flags = HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ;
213 mask = housekeeping_cpumask(hk_flags);
214 /* Wrap: we always want a cpu. */
215 i %= cpumask_weight(mask);
216
217 if (node == NUMA_NO_NODE) {
218 for_each_cpu(cpu, mask) {
219 if (i-- == 0)
220 return cpu;
221 }
222 } else {
223 /* NUMA first. */
224 for_each_cpu_and(cpu, cpumask_of_node(node), mask) {
225 if (i-- == 0)
226 return cpu;
227 }
228
229 for_each_cpu(cpu, mask) {
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;
236 }
237 }
238 BUG();
239 }
240 EXPORT_SYMBOL(cpumask_local_spread);
241
242 static 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 */
cpumask_any_and_distribute(const struct cpumask * src1p,const struct cpumask * src2p)252 int 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 }
269 EXPORT_SYMBOL(cpumask_any_and_distribute);
270
