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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_CPUMASK_TYPES_H
#define __LINUX_CPUMASK_TYPES_H
#include <linux/bitops.h>
#include <linux/threads.h>
/* Don't assign or return these: may not be this big! */
typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
/**
* cpumask_bits - get the bits in a cpumask
* @maskp: the struct cpumask *
*
* You should only assume nr_cpu_ids bits of this mask are valid. This is
* a macro so it's const-correct.
*/
#define cpumask_bits(maskp) ((maskp)->bits)
/*
* cpumask_var_t: struct cpumask for stack usage.
*
* Oh, the wicked games we play! In order to make kernel coding a
* little more difficult, we typedef cpumask_var_t to an array or a
* pointer: doing &mask on an array is a noop, so it still works.
*
* i.e.
* cpumask_var_t tmpmask;
* if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
* return -ENOMEM;
*
* ... use 'tmpmask' like a normal struct cpumask * ...
*
* free_cpumask_var(tmpmask);
*
*
* However, one notable exception is there. alloc_cpumask_var() allocates
* only nr_cpumask_bits bits (in the other hand, real cpumask_t always has
* NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t.
*
* cpumask_var_t tmpmask;
* if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
* return -ENOMEM;
*
* var = *tmpmask;
*
* This code makes NR_CPUS length memcopy and brings to a memory corruption.
* cpumask_copy() provide safe copy functionality.
*
* Note that there is another evil here: If you define a cpumask_var_t
* as a percpu variable then the way to obtain the address of the cpumask
* structure differently influences what this_cpu_* operation needs to be
* used. Please use this_cpu_cpumask_var_t in those cases. The direct use
* of this_cpu_ptr() or this_cpu_read() will lead to failures when the
* other type of cpumask_var_t implementation is configured.
*
* Please also note that __cpumask_var_read_mostly can be used to declare
* a cpumask_var_t variable itself (not its content) as read mostly.
*/
#ifdef CONFIG_CPUMASK_OFFSTACK
typedef struct cpumask *cpumask_var_t;
#else
typedef struct cpumask cpumask_var_t[1];
#endif /* CONFIG_CPUMASK_OFFSTACK */
#endif /* __LINUX_CPUMASK_TYPES_H */
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