// 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);