lib/cpumask.c - linux - Git at Google

 // 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>
 #include <linux/sched/isolation.h>

 /**
  * cpumask_next - get the next cpu in a cpumask
  * @n: the cpu prior to the place to search (ie. return will be > @n)
  * @srcp: the cpumask pointer
  *
  * Returns >= nr_cpu_ids if no further cpus set.
  */
 unsigned int cpumask_next(int n, const struct cpumask *srcp)
 {
 	/* -1 is a legal arg here. */
 	if (n != -1)
 		cpumask_check(n);
 	return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1);
 }
 EXPORT_SYMBOL(cpumask_next);

 /**
  * cpumask_next_and - get the next cpu in *src1p & *src2p
  * @n: the cpu prior to the place to search (ie. return will be > @n)
  * @src1p: the first cpumask pointer
  * @src2p: the second cpumask pointer
  *
  * Returns >= nr_cpu_ids if no further cpus set in both.
  */
 int cpumask_next_and(int n, const struct cpumask *src1p,
 		     const struct cpumask *src2p)
 {
 	/* -1 is a legal arg here. */
 	if (n != -1)
 		cpumask_check(n);
 	return find_next_and_bit(cpumask_bits(src1p), cpumask_bits(src2p),
 		nr_cpumask_bits, n + 1);
 }
 EXPORT_SYMBOL(cpumask_next_and);

 /**
  * cpumask_any_but - return a "random" in a cpumask, but not this one.
  * @mask: the cpumask to search
  * @cpu: the cpu to ignore.
  *
  * Often used to find any cpu but smp_processor_id() in a mask.
  * Returns >= nr_cpu_ids if no cpus set.
  */
 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
 {
 	unsigned int i;

 	cpumask_check(cpu);
 	for_each_cpu(i, mask)
 		if (i != cpu)
 			break;
 	return i;
 }
 EXPORT_SYMBOL(cpumask_any_but);

 /**
  * 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
  *
  * Returns >= nr_cpu_ids on completion
  *
  * Note: the @wrap argument is required for the start condition when
  * we cannot assume @start is set in @mask.
  */
 int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
 {
 	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
  *
  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  * a nop returning a constant 1 (in <linux/cpumask.h>)
  * Returns 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);

 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 {
 	return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
 }
 EXPORT_SYMBOL(zalloc_cpumask_var_node);

 /**
  * alloc_cpumask_var - allocate a struct cpumask
  * @mask: pointer to cpumask_var_t where the cpumask is returned
  * @flags: GFP_ flags
  *
  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  * a nop returning a constant 1 (in <linux/cpumask.h>).
  *
  * See alloc_cpumask_var_node.
  */
 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 {
 	return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
 }
 EXPORT_SYMBOL(alloc_cpumask_var);

 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 {
 	return alloc_cpumask_var(mask, flags | __GFP_ZERO);
 }
 EXPORT_SYMBOL(zalloc_cpumask_var);

 /**
  * 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_early(__pa(mask), cpumask_size());
 }
 #endif

 /**
  * cpumask_local_spread - select the i'th cpu with local numa cpu's first
  * @i: index number
  * @node: local numa_node
  *
  * This function selects an online CPU according to a numa aware policy;
  * local cpus are returned first, followed by non-local ones, then it
  * wraps around.
  *
  * It's not very efficient, but useful for setup.
  */
 unsigned int cpumask_local_spread(unsigned int i, int node)
 {
 	int cpu, hk_flags;
 	const struct cpumask *mask;

 	hk_flags = HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ;
 	mask = housekeeping_cpumask(hk_flags);
 	/* Wrap: we always want a cpu. */
 	i %= cpumask_weight(mask);

 	if (node == NUMA_NO_NODE) {
 		for_each_cpu(cpu, mask) {
 			if (i-- == 0)
 				return cpu;
 		}
 	} else {
 		/* NUMA first. */
 		for_each_cpu_and(cpu, cpumask_of_node(node), mask) {
 			if (i-- == 0)
 				return cpu;
 		}

 		for_each_cpu(cpu, mask) {
 			/* Skip NUMA nodes, done above. */
 			if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
 				continue;

 			if (i-- == 0)
 				return cpu;
 		}
 	}
 	BUG();
 }
 EXPORT_SYMBOL(cpumask_local_spread);

 static DEFINE_PER_CPU(int, distribute_cpu_mask_prev);

 /**
  * Returns an arbitrary cpu within srcp1 & srcp2.
  *
  * Iterated calls using the same srcp1 and srcp2 will be distributed within
  * their intersection.
  *
  * Returns >= nr_cpu_ids if the intersection is empty.
  */
 int cpumask_any_and_distribute(const struct cpumask *src1p,
 			       const struct cpumask *src2p)
 {
 	int next, prev;

 	/* NOTE: our first selection will skip 0. */
 	prev = __this_cpu_read(distribute_cpu_mask_prev);

 	next = cpumask_next_and(prev, src1p, src2p);
 	if (next >= nr_cpu_ids)
 		next = cpumask_first_and(src1p, src2p);

 	if (next < nr_cpu_ids)
 		__this_cpu_write(distribute_cpu_mask_prev, next);

 	return next;
 }
 EXPORT_SYMBOL(cpumask_any_and_distribute);
	// 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>
	#include <linux/sched/isolation.h>

	/**
	* cpumask_next - get the next cpu in a cpumask
	* @n: the cpu prior to the place to search (ie. return will be > @n)
	* @srcp: the cpumask pointer
	*
	* Returns >= nr_cpu_ids if no further cpus set.
	*/
	unsigned int cpumask_next(int n, const struct cpumask *srcp)
	{
	/* -1 is a legal arg here. */
	if (n != -1)
	cpumask_check(n);
	return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1);
	}
	EXPORT_SYMBOL(cpumask_next);

	/**
	* cpumask_next_and - get the next cpu in src1p & src2p
	* @n: the cpu prior to the place to search (ie. return will be > @n)
	* @src1p: the first cpumask pointer
	* @src2p: the second cpumask pointer
	*
	* Returns >= nr_cpu_ids if no further cpus set in both.
	*/
	int cpumask_next_and(int n, const struct cpumask *src1p,
	const struct cpumask *src2p)
	{
	/* -1 is a legal arg here. */
	if (n != -1)
	cpumask_check(n);
	return find_next_and_bit(cpumask_bits(src1p), cpumask_bits(src2p),
	nr_cpumask_bits, n + 1);
	}
	EXPORT_SYMBOL(cpumask_next_and);

	/**
	* cpumask_any_but - return a "random" in a cpumask, but not this one.
	* @mask: the cpumask to search
	* @cpu: the cpu to ignore.
	*
	* Often used to find any cpu but smp_processor_id() in a mask.
	* Returns >= nr_cpu_ids if no cpus set.
	*/
	int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
	{
	unsigned int i;

	cpumask_check(cpu);
	for_each_cpu(i, mask)
	if (i != cpu)
	break;
	return i;
	}
	EXPORT_SYMBOL(cpumask_any_but);

	/**
	* 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
	*
	* Returns >= nr_cpu_ids on completion
	*
	* Note: the @wrap argument is required for the start condition when
	* we cannot assume @start is set in @mask.
	*/
	int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
	{
	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
	*
	* Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
	* a nop returning a constant 1 (in <linux/cpumask.h>)
	* Returns 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);

	bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
	{
	return alloc_cpumask_var_node(mask, flags \| __GFP_ZERO, node);
	}
	EXPORT_SYMBOL(zalloc_cpumask_var_node);

	/**
	* alloc_cpumask_var - allocate a struct cpumask
	* @mask: pointer to cpumask_var_t where the cpumask is returned
	* @flags: GFP_ flags
	*
	* Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
	* a nop returning a constant 1 (in <linux/cpumask.h>).
	*
	* See alloc_cpumask_var_node.
	*/
	bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
	{
	return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
	}
	EXPORT_SYMBOL(alloc_cpumask_var);

	bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
	{
	return alloc_cpumask_var(mask, flags \| __GFP_ZERO);
	}
	EXPORT_SYMBOL(zalloc_cpumask_var);

	/**
	* 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_early(__pa(mask), cpumask_size());
	}
	#endif

	/**
	* cpumask_local_spread - select the i'th cpu with local numa cpu's first
	* @i: index number
	* @node: local numa_node
	*
	* This function selects an online CPU according to a numa aware policy;
	* local cpus are returned first, followed by non-local ones, then it
	* wraps around.
	*
	* It's not very efficient, but useful for setup.
	*/
	unsigned int cpumask_local_spread(unsigned int i, int node)
	{
	int cpu, hk_flags;
	const struct cpumask *mask;

	hk_flags = HK_FLAG_DOMAIN \| HK_FLAG_MANAGED_IRQ;
	mask = housekeeping_cpumask(hk_flags);
	/* Wrap: we always want a cpu. */
	i %= cpumask_weight(mask);

	if (node == NUMA_NO_NODE) {
	for_each_cpu(cpu, mask) {
	if (i-- == 0)
	return cpu;
	}
	} else {
	/* NUMA first. */
	for_each_cpu_and(cpu, cpumask_of_node(node), mask) {
	if (i-- == 0)
	return cpu;
	}

	for_each_cpu(cpu, mask) {
	/* Skip NUMA nodes, done above. */
	if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
	continue;

	if (i-- == 0)
	return cpu;
	}
	}
	BUG();
	}
	EXPORT_SYMBOL(cpumask_local_spread);

	static DEFINE_PER_CPU(int, distribute_cpu_mask_prev);

	/**
	* Returns an arbitrary cpu within srcp1 & srcp2.
	*
	* Iterated calls using the same srcp1 and srcp2 will be distributed within
	* their intersection.
	*
	* Returns >= nr_cpu_ids if the intersection is empty.
	*/
	int cpumask_any_and_distribute(const struct cpumask *src1p,
	const struct cpumask *src2p)
	{
	int next, prev;

	/* NOTE: our first selection will skip 0. */
	prev = __this_cpu_read(distribute_cpu_mask_prev);

	next = cpumask_next_and(prev, src1p, src2p);
	if (next >= nr_cpu_ids)
	next = cpumask_first_and(src1p, src2p);

	if (next < nr_cpu_ids)
	__this_cpu_write(distribute_cpu_mask_prev, next);

	return next;
	}
	EXPORT_SYMBOL(cpumask_any_and_distribute);