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_wrap - helper to implement for_each_cpu_wrap 12 * @n: the cpu prior to the place to search 13 * @mask: the cpumask pointer 14 * @start: the start point of the iteration 15 * @wrap: assume @n crossing @start terminates the iteration 16 * 17 * Return: >= nr_cpu_ids on completion 18 * 19 * Note: the @wrap argument is required for the start condition when 20 * we cannot assume @start is set in @mask. 21 */ 22 unsigned int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap) 23 { 24 unsigned int next; 25 26 again: 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 } 40 EXPORT_SYMBOL(cpumask_next_wrap); 41 42 /* These are not inline because of header tangles. */ 43 #ifdef CONFIG_CPUMASK_OFFSTACK 44 /** 45 * alloc_cpumask_var_node - allocate a struct cpumask on a given node 46 * @mask: pointer to cpumask_var_t where the cpumask is returned 47 * @flags: GFP_ flags 48 * @node: memory node from which to allocate or %NUMA_NO_NODE 49 * 50 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is 51 * 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 is 56 * usually smart enough to know that mask can never be NULL if 57 * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case 58 * too. 59 */ 60 bool 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_MAPS 65 if (!*mask) { 66 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n"); 67 dump_stack(); 68 } 69 #endif 70 71 return *mask != NULL; 72 } 73 EXPORT_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 returned 78 * 79 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is 80 * a nop (in <linux/cpumask.h>). 81 * Either returns an allocated (zero-filled) cpumask, or causes the 82 * system to panic. 83 */ 84 void __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 free 95 * 96 * This is safe on a NULL mask. 97 */ 98 void free_cpumask_var(cpumask_var_t mask) 99 { 100 kfree(mask); 101 } 102 EXPORT_SYMBOL(free_cpumask_var); 103 104 /** 105 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var 106 * @mask: cpumask to free 107 */ 108 void __init free_bootmem_cpumask_var(cpumask_var_t mask) 109 { 110 memblock_free(mask, cpumask_size()); 111 } 112 #endif 113 114 /** 115 * cpumask_local_spread - select the i'th cpu based on NUMA distances 116 * @i: index number 117 * @node: local numa_node 118 * 119 * Return: online CPU according to a numa aware policy; local cpus are returned 120 * 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-based 139 * enumeration is O(sched_domains_numa_levels * nr_cpu_ids), while 140 * cpumask_local_spread() when called for each cpu is 141 * O(sched_domains_numa_levels * nr_cpu_ids * log(nr_cpu_ids)). 142 */ 143 unsigned 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 } 155 EXPORT_SYMBOL(cpumask_local_spread); 156 157 static 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 intersection 162 * @src2p: second &cpumask for intersection 163 * 164 * Iterated calls using the same srcp1 and srcp2 will be distributed within 165 * their intersection. 166 * 167 * Return: >= nr_cpu_ids if the intersection is empty. 168 */ 169 unsigned 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 } 184 EXPORT_SYMBOL(cpumask_any_and_distribute); 185 186 /** 187 * cpumask_any_distribute - Return an arbitrary cpu from srcp 188 * @srcp: &cpumask for selection 189 * 190 * Return: >= nr_cpu_ids if the intersection is empty. 191 */ 192 unsigned 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 } 204 EXPORT_SYMBOL(cpumask_any_distribute); 205