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 */ 15 static inline void native_queued_spin_unlock(struct qspinlock *lock) 16 { 17 smp_store_release((u8 *)lock, 0); 18 } 19 20 #ifdef CONFIG_PARAVIRT_SPINLOCKS 21 extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 22 extern void __pv_init_lock_hash(void); 23 extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 24 extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock); 25 26 static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) 27 { 28 pv_queued_spin_lock_slowpath(lock, val); 29 } 30 31 static inline void queued_spin_unlock(struct qspinlock *lock) 32 { 33 pv_queued_spin_unlock(lock); 34 } 35 #else 36 static 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 44 static 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