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>
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
15 * Returns >= nr_cpu_ids if no further cpus set.
17 unsigned int cpumask_next(int n, const struct cpumask *srcp)
19 /* -1 is a legal arg here. */
22 return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1);
24 EXPORT_SYMBOL(cpumask_next);
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
32 * Returns >= nr_cpu_ids if no further cpus set in both.
34 int cpumask_next_and(int n, const struct cpumask *src1p,
35 const struct cpumask *src2p)
37 /* -1 is a legal arg here. */
40 return find_next_and_bit(cpumask_bits(src1p), cpumask_bits(src2p),
41 nr_cpumask_bits, n + 1);
43 EXPORT_SYMBOL(cpumask_next_and);
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.
50 * Often used to find any cpu but smp_processor_id() in a mask.
51 * Returns >= nr_cpu_ids if no cpus set.
53 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
63 EXPORT_SYMBOL(cpumask_any_but);
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
72 * Returns >= nr_cpu_ids on completion
74 * Note: the @wrap argument is required for the start condition when
75 * we cannot assume @start is set in @mask.
77 int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
82 next = cpumask_next(n, mask);
84 if (wrap && n < start && next >= start) {
85 return nr_cpumask_bits;
87 } else if (next >= nr_cpumask_bits) {
95 EXPORT_SYMBOL(cpumask_next_wrap);
97 /* These are not inline because of header tangles. */
98 #ifdef CONFIG_CPUMASK_OFFSTACK
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
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.
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
113 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
115 *mask = kmalloc_node(cpumask_size(), flags, node);
117 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
119 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
124 return *mask != NULL;
126 EXPORT_SYMBOL(alloc_cpumask_var_node);
128 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
130 return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
132 EXPORT_SYMBOL(zalloc_cpumask_var_node);
135 * alloc_cpumask_var - allocate a struct cpumask
136 * @mask: pointer to cpumask_var_t where the cpumask is returned
139 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
140 * a nop returning a constant 1 (in <linux/cpumask.h>).
142 * See alloc_cpumask_var_node.
144 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
146 return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
148 EXPORT_SYMBOL(alloc_cpumask_var);
150 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
152 return alloc_cpumask_var(mask, flags | __GFP_ZERO);
154 EXPORT_SYMBOL(zalloc_cpumask_var);
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
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
165 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
167 *mask = memblock_alloc(cpumask_size(), SMP_CACHE_BYTES);
169 panic("%s: Failed to allocate %u bytes\n", __func__,
174 * free_cpumask_var - frees memory allocated for a struct cpumask.
175 * @mask: cpumask to free
177 * This is safe on a NULL mask.
179 void free_cpumask_var(cpumask_var_t mask)
183 EXPORT_SYMBOL(free_cpumask_var);
186 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
187 * @mask: cpumask to free
189 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
191 memblock_free(mask, cpumask_size());
196 * cpumask_local_spread - select the i'th cpu with local numa cpu's first
198 * @node: local numa_node
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
204 * It's not very efficient, but useful for setup.
206 unsigned int cpumask_local_spread(unsigned int i, int node)
210 /* Wrap: we always want a cpu. */
211 i %= num_online_cpus();
213 if (node == NUMA_NO_NODE) {
214 for_each_cpu(cpu, cpu_online_mask)
219 for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
223 for_each_cpu(cpu, cpu_online_mask) {
224 /* Skip NUMA nodes, done above. */
225 if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
234 EXPORT_SYMBOL(cpumask_local_spread);
236 static DEFINE_PER_CPU(int, distribute_cpu_mask_prev);
239 * Returns an arbitrary cpu within srcp1 & srcp2.
241 * Iterated calls using the same srcp1 and srcp2 will be distributed within
242 * their intersection.
244 * Returns >= nr_cpu_ids if the intersection is empty.
246 int cpumask_any_and_distribute(const struct cpumask *src1p,
247 const struct cpumask *src2p)
251 /* NOTE: our first selection will skip 0. */
252 prev = __this_cpu_read(distribute_cpu_mask_prev);
254 next = cpumask_next_and(prev, src1p, src2p);
255 if (next >= nr_cpu_ids)
256 next = cpumask_first_and(src1p, src2p);
258 if (next < nr_cpu_ids)
259 __this_cpu_write(distribute_cpu_mask_prev, next);
263 EXPORT_SYMBOL(cpumask_any_and_distribute);
265 int cpumask_any_distribute(const struct cpumask *srcp)
269 /* NOTE: our first selection will skip 0. */
270 prev = __this_cpu_read(distribute_cpu_mask_prev);
272 next = cpumask_next(prev, srcp);
273 if (next >= nr_cpu_ids)
274 next = cpumask_first(srcp);
276 if (next < nr_cpu_ids)
277 __this_cpu_write(distribute_cpu_mask_prev, next);
281 EXPORT_SYMBOL(cpumask_any_distribute);