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_or_panic(cpumask_size(), SMP_CACHE_BYTES); 87 } 88 89 /** 90 * free_cpumask_var - frees memory allocated for a struct cpumask. 91 * @mask: cpumask to free 92 * 93 * This is safe on a NULL mask. 94 */ 95 void free_cpumask_var(cpumask_var_t mask) 96 { 97 kfree(mask); 98 } 99 EXPORT_SYMBOL(free_cpumask_var); 100 101 /** 102 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var 103 * @mask: cpumask to free 104 */ 105 void __init free_bootmem_cpumask_var(cpumask_var_t mask) 106 { 107 memblock_free(mask, cpumask_size()); 108 } 109 #endif 110 111 /** 112 * cpumask_local_spread - select the i'th cpu based on NUMA distances 113 * @i: index number 114 * @node: local numa_node 115 * 116 * Return: online CPU according to a numa aware policy; local cpus are returned 117 * first, followed by non-local ones, then it wraps around. 118 * 119 * For those who wants to enumerate all CPUs based on their NUMA distances, 120 * i.e. call this function in a loop, like: 121 * 122 * for (i = 0; i < num_online_cpus(); i++) { 123 * cpu = cpumask_local_spread(i, node); 124 * do_something(cpu); 125 * } 126 * 127 * There's a better alternative based on for_each()-like iterators: 128 * 129 * for_each_numa_hop_mask(mask, node) { 130 * for_each_cpu_andnot(cpu, mask, prev) 131 * do_something(cpu); 132 * prev = mask; 133 * } 134 * 135 * It's simpler and more verbose than above. Complexity of iterator-based 136 * enumeration is O(sched_domains_numa_levels * nr_cpu_ids), while 137 * cpumask_local_spread() when called for each cpu is 138 * O(sched_domains_numa_levels * nr_cpu_ids * log(nr_cpu_ids)). 139 */ 140 unsigned int cpumask_local_spread(unsigned int i, int node) 141 { 142 unsigned int cpu; 143 144 /* Wrap: we always want a cpu. */ 145 i %= num_online_cpus(); 146 147 cpu = sched_numa_find_nth_cpu(cpu_online_mask, i, node); 148 149 WARN_ON(cpu >= nr_cpu_ids); 150 return cpu; 151 } 152 EXPORT_SYMBOL(cpumask_local_spread); 153 154 static DEFINE_PER_CPU(int, distribute_cpu_mask_prev); 155 156 /** 157 * cpumask_any_and_distribute - Return an arbitrary cpu within src1p & src2p. 158 * @src1p: first &cpumask for intersection 159 * @src2p: second &cpumask for intersection 160 * 161 * Iterated calls using the same srcp1 and srcp2 will be distributed within 162 * their intersection. 163 * 164 * Return: >= nr_cpu_ids if the intersection is empty. 165 */ 166 unsigned int cpumask_any_and_distribute(const struct cpumask *src1p, 167 const struct cpumask *src2p) 168 { 169 unsigned int next, prev; 170 171 /* NOTE: our first selection will skip 0. */ 172 prev = __this_cpu_read(distribute_cpu_mask_prev); 173 174 next = find_next_and_bit_wrap(cpumask_bits(src1p), cpumask_bits(src2p), 175 nr_cpumask_bits, prev + 1); 176 if (next < nr_cpu_ids) 177 __this_cpu_write(distribute_cpu_mask_prev, next); 178 179 return next; 180 } 181 EXPORT_SYMBOL(cpumask_any_and_distribute); 182 183 /** 184 * cpumask_any_distribute - Return an arbitrary cpu from srcp 185 * @srcp: &cpumask for selection 186 * 187 * Return: >= nr_cpu_ids if the intersection is empty. 188 */ 189 unsigned int cpumask_any_distribute(const struct cpumask *srcp) 190 { 191 unsigned int next, prev; 192 193 /* NOTE: our first selection will skip 0. */ 194 prev = __this_cpu_read(distribute_cpu_mask_prev); 195 next = find_next_bit_wrap(cpumask_bits(srcp), nr_cpumask_bits, prev + 1); 196 if (next < nr_cpu_ids) 197 __this_cpu_write(distribute_cpu_mask_prev, next); 198 199 return next; 200 } 201 EXPORT_SYMBOL(cpumask_any_distribute); 202