// 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!
  ");
  		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
  ", __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);