1#ifndef _ASM_X86_QSPINLOCK_H
2#define _ASM_X86_QSPINLOCK_H
3
4#include <asm/cpufeature.h>
5#include <asm-generic/qspinlock_types.h>
6#include <asm/paravirt.h>
7
8#define	queued_spin_unlock queued_spin_unlock
9/**
10 * queued_spin_unlock - release a queued spinlock
11 * @lock : Pointer to queued spinlock structure
12 *
13 * A smp_store_release() on the least-significant byte.
14 */
15static inline void native_queued_spin_unlock(struct qspinlock *lock)
16{
17	smp_store_release((u8 *)lock, 0);
18}
19
20#ifdef CONFIG_PARAVIRT_SPINLOCKS
21extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
22extern void __pv_init_lock_hash(void);
23extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
24extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
25
26static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
27{
28	pv_queued_spin_lock_slowpath(lock, val);
29}
30
31static inline void queued_spin_unlock(struct qspinlock *lock)
32{
33	pv_queued_spin_unlock(lock);
34}
35#else
36static inline void queued_spin_unlock(struct qspinlock *lock)
37{
38	native_queued_spin_unlock(lock);
39}
40#endif
41
42#ifdef CONFIG_PARAVIRT
43#define virt_spin_lock virt_spin_lock
44static inline bool virt_spin_lock(struct qspinlock *lock)
45{
46	if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
47		return false;
48
49	/*
50	 * On hypervisors without PARAVIRT_SPINLOCKS support we fall
51	 * back to a Test-and-Set spinlock, because fair locks have
52	 * horrible lock 'holder' preemption issues.
53	 */
54
55	do {
56		while (atomic_read(&lock->val) != 0)
57			cpu_relax();
58	} while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0);
59
60	return true;
61}
62#endif /* CONFIG_PARAVIRT */
63
64#include <asm-generic/qspinlock.h>
65
66#endif /* _ASM_X86_QSPINLOCK_H */
67