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 * Returns >= 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 * 49 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is 50 * a nop returning a constant 1 (in <linux/cpumask.h>) 51 * Returns TRUE if memory allocation succeeded, FALSE otherwise. 52 * 53 * In addition, mask will be NULL if this fails. Note that gcc is 54 * usually smart enough to know that mask can never be NULL if 55 * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case 56 * too. 57 */ 58 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node) 59 { 60 *mask = kmalloc_node(cpumask_size(), flags, node); 61 62 #ifdef CONFIG_DEBUG_PER_CPU_MAPS 63 if (!*mask) { 64 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n"); 65 dump_stack(); 66 } 67 #endif 68 69 return *mask != NULL; 70 } 71 EXPORT_SYMBOL(alloc_cpumask_var_node); 72 73 /** 74 * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena. 75 * @mask: pointer to cpumask_var_t where the cpumask is returned 76 * 77 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is 78 * a nop (in <linux/cpumask.h>). 79 * Either returns an allocated (zero-filled) cpumask, or causes the 80 * system to panic. 81 */ 82 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask) 83 { 84 *mask = memblock_alloc(cpumask_size(), SMP_CACHE_BYTES); 85 if (!*mask) 86 panic("%s: Failed to allocate %u bytes\n", __func__, 87 cpumask_size()); 88 } 89 90 /** 91 * free_cpumask_var - frees memory allocated for a struct cpumask. 92 * @mask: cpumask to free 93 * 94 * This is safe on a NULL mask. 95 */ 96 void free_cpumask_var(cpumask_var_t mask) 97 { 98 kfree(mask); 99 } 100 EXPORT_SYMBOL(free_cpumask_var); 101 102 /** 103 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var 104 * @mask: cpumask to free 105 */ 106 void __init free_bootmem_cpumask_var(cpumask_var_t mask) 107 { 108 memblock_free(mask, cpumask_size()); 109 } 110 #endif 111 112 /** 113 * cpumask_local_spread - select the i'th cpu with local numa cpu's first 114 * @i: index number 115 * @node: local numa_node 116 * 117 * This function selects an online CPU according to a numa aware policy; 118 * local cpus are returned first, followed by non-local ones, then it 119 * wraps around. 120 * 121 * It's not very efficient, but useful for setup. 122 */ 123 unsigned int cpumask_local_spread(unsigned int i, int node) 124 { 125 unsigned int cpu; 126 127 /* Wrap: we always want a cpu. */ 128 i %= num_online_cpus(); 129 130 if (node == NUMA_NO_NODE) { 131 cpu = cpumask_nth(i, cpu_online_mask); 132 if (cpu < nr_cpu_ids) 133 return cpu; 134 } else { 135 /* NUMA first. */ 136 cpu = cpumask_nth_and(i, cpu_online_mask, cpumask_of_node(node)); 137 if (cpu < nr_cpu_ids) 138 return cpu; 139 140 i -= cpumask_weight_and(cpu_online_mask, cpumask_of_node(node)); 141 142 /* Skip NUMA nodes, done above. */ 143 cpu = cpumask_nth_andnot(i, cpu_online_mask, cpumask_of_node(node)); 144 if (cpu < nr_cpu_ids) 145 return cpu; 146 } 147 BUG(); 148 } 149 EXPORT_SYMBOL(cpumask_local_spread); 150 151 static DEFINE_PER_CPU(int, distribute_cpu_mask_prev); 152 153 /** 154 * Returns an arbitrary cpu within srcp1 & srcp2. 155 * 156 * Iterated calls using the same srcp1 and srcp2 will be distributed within 157 * their intersection. 158 * 159 * Returns >= nr_cpu_ids if the intersection is empty. 160 */ 161 unsigned int cpumask_any_and_distribute(const struct cpumask *src1p, 162 const struct cpumask *src2p) 163 { 164 unsigned int next, prev; 165 166 /* NOTE: our first selection will skip 0. */ 167 prev = __this_cpu_read(distribute_cpu_mask_prev); 168 169 next = find_next_and_bit_wrap(cpumask_bits(src1p), cpumask_bits(src2p), 170 nr_cpumask_bits, prev + 1); 171 if (next < nr_cpu_ids) 172 __this_cpu_write(distribute_cpu_mask_prev, next); 173 174 return next; 175 } 176 EXPORT_SYMBOL(cpumask_any_and_distribute); 177 178 unsigned int cpumask_any_distribute(const struct cpumask *srcp) 179 { 180 unsigned int next, prev; 181 182 /* NOTE: our first selection will skip 0. */ 183 prev = __this_cpu_read(distribute_cpu_mask_prev); 184 next = find_next_bit_wrap(cpumask_bits(srcp), nr_cpumask_bits, prev + 1); 185 if (next < nr_cpu_ids) 186 __this_cpu_write(distribute_cpu_mask_prev, next); 187 188 return next; 189 } 190 EXPORT_SYMBOL(cpumask_any_distribute); 191