Release 4.18 arch/x86/include/asm/qspinlock.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_QSPINLOCK_H

#define _ASM_X86_QSPINLOCK_H

#include <linux/jump_label.h>
#include <asm/cpufeature.h>
#include <asm-generic/qspinlock_types.h>
#include <asm/paravirt.h>


#define _Q_PENDING_LOOPS	(1 << 9)

#ifdef CONFIG_PARAVIRT_SPINLOCKS
extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
extern void __pv_init_lock_hash(void);
extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);


#define	queued_spin_unlock queued_spin_unlock
/**
 * queued_spin_unlock - release a queued spinlock
 * @lock : Pointer to queued spinlock structure
 *
 * A smp_store_release() on the least-significant byte.
 */


static inline void native_queued_spin_unlock(struct qspinlock *lock)
{
	smp_store_release(&lock->locked, 0);
}

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static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
{
	pv_queued_spin_lock_slowpath(lock, val);
}

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static inline void queued_spin_unlock(struct qspinlock *lock)
{
	pv_queued_spin_unlock(lock);
}

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#define vcpu_is_preempted vcpu_is_preempted


static inline bool vcpu_is_preempted(long cpu)
{
	return pv_vcpu_is_preempted(cpu);
}
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#endif

#ifdef CONFIG_PARAVIRT
DECLARE_STATIC_KEY_TRUE(virt_spin_lock_key);

void native_pv_lock_init(void) __init;


#define virt_spin_lock virt_spin_lock


static inline bool virt_spin_lock(struct qspinlock *lock)
{
	if (!static_branch_likely(&virt_spin_lock_key))
		return false;

	/*
         * On hypervisors without PARAVIRT_SPINLOCKS support we fall
         * back to a Test-and-Set spinlock, because fair locks have
         * horrible lock 'holder' preemption issues.
         */

	do {
		while (atomic_read(&lock->val) != 0)
			cpu_relax();
	} while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0);

	return true;
}
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#else


static inline void native_pv_lock_init(void)
{
}
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#endif /* CONFIG_PARAVIRT */

#include <asm-generic/qspinlock.h>

#endif /* _ASM_X86_QSPINLOCK_H */
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Directory: arch/x86/include/asm

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