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 - 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 14 * 15 * Returns >= nr_cpu_ids if no further cpus set. 16 */ 17 unsigned int cpumask_next(int n, const struct cpumask *srcp) 18 { 19 /* -1 is a legal arg here. */ 20 if (n != -1) 21 cpumask_check(n); 22 return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1); 23 } 24 EXPORT_SYMBOL(cpumask_next); 25 26 /** 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 31 * 32 * Returns >= nr_cpu_ids if no further cpus set in both. 33 */ 34 int cpumask_next_and(int n, const struct cpumask *src1p, 35 const struct cpumask *src2p) 36 { 37 /* -1 is a legal arg here. */ 38 if (n != -1) 39 cpumask_check(n); 40 return find_next_and_bit(cpumask_bits(src1p), cpumask_bits(src2p), 41 nr_cpumask_bits, n + 1); 42 } 43 EXPORT_SYMBOL(cpumask_next_and); 44 45 /** 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. 49 * 50 * Often used to find any cpu but smp_processor_id() in a mask. 51 * Returns >= nr_cpu_ids if no cpus set. 52 */ 53 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu) 54 { 55 unsigned int i; 56 57 cpumask_check(cpu); 58 for_each_cpu(i, mask) 59 if (i != cpu) 60 break; 61 return i; 62 } 63 EXPORT_SYMBOL(cpumask_any_but); 64 65 /** 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 71 * 72 * Returns >= nr_cpu_ids on completion 73 * 74 * Note: the @wrap argument is required for the start condition when 75 * we cannot assume @start is set in @mask. 76 */ 77 int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap) 78 { 79 int next; 80 81 again: 82 next = cpumask_next(n, mask); 83 84 if (wrap && n < start && next >= start) { 85 return nr_cpumask_bits; 86 87 } else if (next >= nr_cpumask_bits) { 88 wrap = true; 89 n = -1; 90 goto again; 91 } 92 93 return next; 94 } 95 EXPORT_SYMBOL(cpumask_next_wrap); 96 97 /* These are not inline because of header tangles. */ 98 #ifdef CONFIG_CPUMASK_OFFSTACK 99 /** 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 102 * @flags: GFP_ flags 103 * 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. 107 * 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 111 * too. 112 */ 113 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node) 114 { 115 *mask = kmalloc_node(cpumask_size(), flags, node); 116 117 #ifdef CONFIG_DEBUG_PER_CPU_MAPS 118 if (!*mask) { 119 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n"); 120 dump_stack(); 121 } 122 #endif 123 124 return *mask != NULL; 125 } 126 EXPORT_SYMBOL(alloc_cpumask_var_node); 127 128 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node) 129 { 130 return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node); 131 } 132 EXPORT_SYMBOL(zalloc_cpumask_var_node); 133 134 /** 135 * alloc_cpumask_var - allocate a struct cpumask 136 * @mask: pointer to cpumask_var_t where the cpumask is returned 137 * @flags: GFP_ flags 138 * 139 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is 140 * a nop returning a constant 1 (in <linux/cpumask.h>). 141 * 142 * See alloc_cpumask_var_node. 143 */ 144 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags) 145 { 146 return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE); 147 } 148 EXPORT_SYMBOL(alloc_cpumask_var); 149 150 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags) 151 { 152 return alloc_cpumask_var(mask, flags | __GFP_ZERO); 153 } 154 EXPORT_SYMBOL(zalloc_cpumask_var); 155 156 /** 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 159 * 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 163 * system to panic. 164 */ 165 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask) 166 { 167 *mask = memblock_alloc(cpumask_size(), SMP_CACHE_BYTES); 168 if (!*mask) 169 panic("%s: Failed to allocate %u bytes\n", __func__, 170 cpumask_size()); 171 } 172 173 /** 174 * free_cpumask_var - frees memory allocated for a struct cpumask. 175 * @mask: cpumask to free 176 * 177 * This is safe on a NULL mask. 178 */ 179 void free_cpumask_var(cpumask_var_t mask) 180 { 181 kfree(mask); 182 } 183 EXPORT_SYMBOL(free_cpumask_var); 184 185 /** 186 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var 187 * @mask: cpumask to free 188 */ 189 void __init free_bootmem_cpumask_var(cpumask_var_t mask) 190 { 191 memblock_free(mask, cpumask_size()); 192 } 193 #endif 194 195 /** 196 * cpumask_local_spread - select the i'th cpu with local numa cpu's first 197 * @i: index number 198 * @node: local numa_node 199 * 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 202 * wraps around. 203 * 204 * It's not very efficient, but useful for setup. 205 */ 206 unsigned int cpumask_local_spread(unsigned int i, int node) 207 { 208 int cpu; 209 210 /* Wrap: we always want a cpu. */ 211 i %= num_online_cpus(); 212 213 if (node == NUMA_NO_NODE) { 214 for_each_cpu(cpu, cpu_online_mask) 215 if (i-- == 0) 216 return cpu; 217 } else { 218 /* NUMA first. */ 219 for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask) 220 if (i-- == 0) 221 return cpu; 222 223 for_each_cpu(cpu, cpu_online_mask) { 224 /* Skip NUMA nodes, done above. */ 225 if (cpumask_test_cpu(cpu, cpumask_of_node(node))) 226 continue; 227 228 if (i-- == 0) 229 return cpu; 230 } 231 } 232 BUG(); 233 } 234 EXPORT_SYMBOL(cpumask_local_spread); 235 236 static DEFINE_PER_CPU(int, distribute_cpu_mask_prev); 237 238 /** 239 * Returns an arbitrary cpu within srcp1 & srcp2. 240 * 241 * Iterated calls using the same srcp1 and srcp2 will be distributed within 242 * their intersection. 243 * 244 * Returns >= nr_cpu_ids if the intersection is empty. 245 */ 246 int cpumask_any_and_distribute(const struct cpumask *src1p, 247 const struct cpumask *src2p) 248 { 249 int next, prev; 250 251 /* NOTE: our first selection will skip 0. */ 252 prev = __this_cpu_read(distribute_cpu_mask_prev); 253 254 next = cpumask_next_and(prev, src1p, src2p); 255 if (next >= nr_cpu_ids) 256 next = cpumask_first_and(src1p, src2p); 257 258 if (next < nr_cpu_ids) 259 __this_cpu_write(distribute_cpu_mask_prev, next); 260 261 return next; 262 } 263 EXPORT_SYMBOL(cpumask_any_and_distribute); 264 265 int cpumask_any_distribute(const struct cpumask *srcp) 266 { 267 int next, prev; 268 269 /* NOTE: our first selection will skip 0. */ 270 prev = __this_cpu_read(distribute_cpu_mask_prev); 271 272 next = cpumask_next(prev, srcp); 273 if (next >= nr_cpu_ids) 274 next = cpumask_first(srcp); 275 276 if (next < nr_cpu_ids) 277 __this_cpu_write(distribute_cpu_mask_prev, next); 278 279 return next; 280 } 281 EXPORT_SYMBOL(cpumask_any_distribute); 282