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 */ 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 */ 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 */ 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 */ 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 */ 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); 128 129 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 */ 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); 150 151 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 */ 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 */ 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 */ 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 */ 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 */ 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