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1// SPDX-License-Identifier: GPL-2.02#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_wrap - helper to implement for_each_cpu_wrap12 * @n: the cpu prior to the place to search13 * @mask: the cpumask pointer14 * @start: the start point of the iteration15 * @wrap: assume @n crossing @start terminates the iteration16 *17 * Return: >= nr_cpu_ids on completion18 *19 * Note: the @wrap argument is required for the start condition when20 * we cannot assume @start is set in @mask.21 */22unsigned int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)23{24 unsigned int next;25 26again:27 next = cpumask_next(n, mask);28 29 if (wrap && n < start && next >= start) {30 return nr_cpumask_bits;31 32 } else if (next >= nr_cpumask_bits) {33 wrap = true;34 n = -1;35 goto again;36 }37 38 return next;39}40EXPORT_SYMBOL(cpumask_next_wrap);41 42/* These are not inline because of header tangles. */43#ifdef CONFIG_CPUMASK_OFFSTACK44/**45 * alloc_cpumask_var_node - allocate a struct cpumask on a given node46 * @mask: pointer to cpumask_var_t where the cpumask is returned47 * @flags: GFP_ flags48 * @node: memory node from which to allocate or %NUMA_NO_NODE49 *50 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is51 * a nop returning a constant 1 (in <linux/cpumask.h>).52 *53 * Return: TRUE if memory allocation succeeded, FALSE otherwise.54 *55 * In addition, mask will be NULL if this fails. Note that gcc is56 * usually smart enough to know that mask can never be NULL if57 * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case58 * too.59 */60bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)61{62 *mask = kmalloc_node(cpumask_size(), flags, node);63 64#ifdef CONFIG_DEBUG_PER_CPU_MAPS65 if (!*mask) {66 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");67 dump_stack();68 }69#endif70 71 return *mask != NULL;72}73EXPORT_SYMBOL(alloc_cpumask_var_node);74 75/**76 * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.77 * @mask: pointer to cpumask_var_t where the cpumask is returned78 *79 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is80 * a nop (in <linux/cpumask.h>).81 * Either returns an allocated (zero-filled) cpumask, or causes the82 * system to panic.83 */84void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)85{86 *mask = memblock_alloc(cpumask_size(), SMP_CACHE_BYTES);87 if (!*mask)88 panic("%s: Failed to allocate %u bytes\n", __func__,89 cpumask_size());90}91 92/**93 * free_cpumask_var - frees memory allocated for a struct cpumask.94 * @mask: cpumask to free95 *96 * This is safe on a NULL mask.97 */98void free_cpumask_var(cpumask_var_t mask)99{100 kfree(mask);101}102EXPORT_SYMBOL(free_cpumask_var);103 104/**105 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var106 * @mask: cpumask to free107 */108void __init free_bootmem_cpumask_var(cpumask_var_t mask)109{110 memblock_free(mask, cpumask_size());111}112#endif113 114/**115 * cpumask_local_spread - select the i'th cpu based on NUMA distances116 * @i: index number117 * @node: local numa_node118 *119 * Return: online CPU according to a numa aware policy; local cpus are returned120 * first, followed by non-local ones, then it wraps around.121 *122 * For those who wants to enumerate all CPUs based on their NUMA distances,123 * i.e. call this function in a loop, like:124 *125 * for (i = 0; i < num_online_cpus(); i++) {126 * cpu = cpumask_local_spread(i, node);127 * do_something(cpu);128 * }129 *130 * There's a better alternative based on for_each()-like iterators:131 *132 * for_each_numa_hop_mask(mask, node) {133 * for_each_cpu_andnot(cpu, mask, prev)134 * do_something(cpu);135 * prev = mask;136 * }137 *138 * It's simpler and more verbose than above. Complexity of iterator-based139 * enumeration is O(sched_domains_numa_levels * nr_cpu_ids), while140 * cpumask_local_spread() when called for each cpu is141 * O(sched_domains_numa_levels * nr_cpu_ids * log(nr_cpu_ids)).142 */143unsigned int cpumask_local_spread(unsigned int i, int node)144{145 unsigned int cpu;146 147 /* Wrap: we always want a cpu. */148 i %= num_online_cpus();149 150 cpu = sched_numa_find_nth_cpu(cpu_online_mask, i, node);151 152 WARN_ON(cpu >= nr_cpu_ids);153 return cpu;154}155EXPORT_SYMBOL(cpumask_local_spread);156 157static DEFINE_PER_CPU(int, distribute_cpu_mask_prev);158 159/**160 * cpumask_any_and_distribute - Return an arbitrary cpu within src1p & src2p.161 * @src1p: first &cpumask for intersection162 * @src2p: second &cpumask for intersection163 *164 * Iterated calls using the same srcp1 and srcp2 will be distributed within165 * their intersection.166 *167 * Return: >= nr_cpu_ids if the intersection is empty.168 */169unsigned int cpumask_any_and_distribute(const struct cpumask *src1p,170 const struct cpumask *src2p)171{172 unsigned int next, prev;173 174 /* NOTE: our first selection will skip 0. */175 prev = __this_cpu_read(distribute_cpu_mask_prev);176 177 next = find_next_and_bit_wrap(cpumask_bits(src1p), cpumask_bits(src2p),178 nr_cpumask_bits, prev + 1);179 if (next < nr_cpu_ids)180 __this_cpu_write(distribute_cpu_mask_prev, next);181 182 return next;183}184EXPORT_SYMBOL(cpumask_any_and_distribute);185 186/**187 * cpumask_any_distribute - Return an arbitrary cpu from srcp188 * @srcp: &cpumask for selection189 *190 * Return: >= nr_cpu_ids if the intersection is empty.191 */192unsigned int cpumask_any_distribute(const struct cpumask *srcp)193{194 unsigned int next, prev;195 196 /* NOTE: our first selection will skip 0. */197 prev = __this_cpu_read(distribute_cpu_mask_prev);198 next = find_next_bit_wrap(cpumask_bits(srcp), nr_cpumask_bits, prev + 1);199 if (next < nr_cpu_ids)200 __this_cpu_write(distribute_cpu_mask_prev, next);201 202 return next;203}204EXPORT_SYMBOL(cpumask_any_distribute);205