/* SPDX-License-Identifier: GPL-2.0 */#ifndef __LINUX_BIT_SPINLOCK_H#define __LINUX_BIT_SPINLOCK_H #include <linux/kernel.h>#include <linux/preempt.h>#include <linux/atomic.h>#include <linux/bug.h> #include <asm/processor.h>  /* for cpu_relax() */ /* * For static context analysis, we need a unique token for each possible bit * that can be used as a bit_spinlock. The easiest way to do that is to create a * fake context that we can cast to with the __bitlock(bitnum, addr) macro * below, which will give us unique instances for each (bit, addr) pair that the * static analysis can use. */context_lock_struct(__context_bitlock) { };#define __bitlock(bitnum, addr) (struct __context_bitlock *)(bitnum + (addr)) /* *  bit-based spin_lock() * * Don't use this unless you really need to: spin_lock() and spin_unlock() * are significantly faster. */static __always_inline void bit_spin_lock(int bitnum, unsigned long *addr)	__acquires(__bitlock(bitnum, addr)){	/*	 * Assuming the lock is uncontended, this never enters	 * the body of the outer loop. If it is contended, then	 * within the inner loop a non-atomic test is used to	 * busywait with less bus contention for a good time to	 * attempt to acquire the lock bit.	 */	preempt_disable();#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)	while (unlikely(test_and_set_bit_lock(bitnum, addr))) {		preempt_enable();		do {			cpu_relax();		} while (test_bit(bitnum, addr));		preempt_disable();	}#endif	__acquire(__bitlock(bitnum, addr));} /* * Return true if it was acquired */static __always_inline int bit_spin_trylock(int bitnum, unsigned long *addr)	__cond_acquires(true, __bitlock(bitnum, addr)){	preempt_disable();#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)	if (unlikely(test_and_set_bit_lock(bitnum, addr))) {		preempt_enable();		return 0;	}#endif	__acquire(__bitlock(bitnum, addr));	return 1;} /* *  bit-based spin_unlock() */static __always_inline void bit_spin_unlock(int bitnum, unsigned long *addr)	__releases(__bitlock(bitnum, addr)){#ifdef CONFIG_DEBUG_SPINLOCK	BUG_ON(!test_bit(bitnum, addr));#endif#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)	clear_bit_unlock(bitnum, addr);#endif	preempt_enable();	__release(__bitlock(bitnum, addr));} /* *  bit-based spin_unlock() *  non-atomic version, which can be used eg. if the bit lock itself is *  protecting the rest of the flags in the word. */static __always_inline void __bit_spin_unlock(int bitnum, unsigned long *addr)	__releases(__bitlock(bitnum, addr)){#ifdef CONFIG_DEBUG_SPINLOCK	BUG_ON(!test_bit(bitnum, addr));#endif#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)	__clear_bit_unlock(bitnum, addr);#endif	preempt_enable();	__release(__bitlock(bitnum, addr));} /* * Return true if the lock is held. */static inline int bit_spin_is_locked(int bitnum, unsigned long *addr){#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)	return test_bit(bitnum, addr);#elif defined CONFIG_PREEMPT_COUNT	return preempt_count();#else	return 1;#endif} #endif /* __LINUX_BIT_SPINLOCK_H */