// SPDX-License-Identifier: GPL-2.0 #include <linux/slab.h> #include <linux/kernel.h> #include <linux/bitops.h> #include <linux/cpumask.h> #include <linux/export.h> #include <linux/memblock.h> #include <linux/numa.h> /** * cpumask_next_wrap - helper to implement for_each_cpu_wrap * @n: the cpu prior to the place to search * @mask: the cpumask pointer * @start: the start point of the iteration * @wrap: assume @n crossing @start terminates the iteration * * Return: >= nr_cpu_ids on completion * * Note: the @wrap argument is required for the start condition when * we cannot assume @start is set in @mask. */ unsigned int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap) { unsigned int next; again: next = cpumask_next(n, mask); if (wrap && n < start && next >= start) { return nr_cpumask_bits; } else if (next >= nr_cpumask_bits) { wrap = true; n = -1; goto again; } return next; } EXPORT_SYMBOL(cpumask_next_wrap); /* These are not inline because of header tangles. */ #ifdef CONFIG_CPUMASK_OFFSTACK /** * alloc_cpumask_var_node - allocate a struct cpumask on a given node * @mask: pointer to cpumask_var_t where the cpumask is returned * @flags: GFP_ flags * @node: memory node from which to allocate or %NUMA_NO_NODE * * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is * a nop returning a constant 1 (in <linux/cpumask.h>). * * Return: TRUE if memory allocation succeeded, FALSE otherwise. * * In addition, mask will be NULL if this fails. Note that gcc is * usually smart enough to know that mask can never be NULL if * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case * too. */ bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node) { *mask = kmalloc_node(cpumask_size(), flags, node); #ifdef CONFIG_DEBUG_PER_CPU_MAPS if (!*mask) { printk(KERN_ERR "=> alloc_cpumask_var: failed!\n"); dump_stack(); } #endif return *mask != NULL; } EXPORT_SYMBOL(alloc_cpumask_var_node); /** * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena. * @mask: pointer to cpumask_var_t where the cpumask is returned * * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is * a nop (in <linux/cpumask.h>). * Either returns an allocated (zero-filled) cpumask, or causes the * system to panic. */ void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask) { *mask = memblock_alloc(cpumask_size(), SMP_CACHE_BYTES); if (!*mask) panic("%s: Failed to allocate %u bytes\n", __func__, cpumask_size()); } /** * free_cpumask_var - frees memory allocated for a struct cpumask. * @mask: cpumask to free * * This is safe on a NULL mask. */ void free_cpumask_var(cpumask_var_t mask) { kfree(mask); } EXPORT_SYMBOL(free_cpumask_var); /** * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var * @mask: cpumask to free */ void __init free_bootmem_cpumask_var(cpumask_var_t mask) { memblock_free(mask, cpumask_size()); } #endif /** * cpumask_local_spread - select the i'th cpu based on NUMA distances * @i: index number * @node: local numa_node * * Return: online CPU according to a numa aware policy; local cpus are returned * first, followed by non-local ones, then it wraps around. * * For those who wants to enumerate all CPUs based on their NUMA distances, * i.e. call this function in a loop, like: * * for (i = 0; i < num_online_cpus(); i++) { * cpu = cpumask_local_spread(i, node); * do_something(cpu); * } * * There's a better alternative based on for_each()-like iterators: * * for_each_numa_hop_mask(mask, node) { * for_each_cpu_andnot(cpu, mask, prev) * do_something(cpu); * prev = mask; * } * * It's simpler and more verbose than above. Complexity of iterator-based * enumeration is O(sched_domains_numa_levels * nr_cpu_ids), while * cpumask_local_spread() when called for each cpu is * O(sched_domains_numa_levels * nr_cpu_ids * log(nr_cpu_ids)). */ unsigned int cpumask_local_spread(unsigned int i, int node) { unsigned int cpu; /* Wrap: we always want a cpu. */ i %= num_online_cpus(); cpu = sched_numa_find_nth_cpu(cpu_online_mask, i, node); WARN_ON(cpu >= nr_cpu_ids); return cpu; } EXPORT_SYMBOL(cpumask_local_spread); static DEFINE_PER_CPU(int, distribute_cpu_mask_prev); /** * cpumask_any_and_distribute - Return an arbitrary cpu within src1p & src2p. * @src1p: first &cpumask for intersection * @src2p: second &cpumask for intersection * * Iterated calls using the same srcp1 and srcp2 will be distributed within * their intersection. * * Return: >= nr_cpu_ids if the intersection is empty. */ unsigned int cpumask_any_and_distribute(const struct cpumask *src1p, const struct cpumask *src2p) { unsigned int next, prev; /* NOTE: our first selection will skip 0. */ prev = __this_cpu_read(distribute_cpu_mask_prev); next = find_next_and_bit_wrap(cpumask_bits(src1p), cpumask_bits(src2p), nr_cpumask_bits, prev + 1); if (next < nr_cpu_ids) __this_cpu_write(distribute_cpu_mask_prev, next); return next; } EXPORT_SYMBOL(cpumask_any_and_distribute); /** * cpumask_any_distribute - Return an arbitrary cpu from srcp * @srcp: &cpumask for selection * * Return: >= nr_cpu_ids if the intersection is empty. */ unsigned int cpumask_any_distribute(const struct cpumask *srcp) { unsigned int next, prev; /* NOTE: our first selection will skip 0. */ prev = __this_cpu_read(distribute_cpu_mask_prev); next = find_next_bit_wrap(cpumask_bits(srcp), nr_cpumask_bits, prev + 1); if (next < nr_cpu_ids) __this_cpu_write(distribute_cpu_mask_prev, next); return next; } EXPORT_SYMBOL(cpumask_any_distribute);