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| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
|---|---|
| 2 | #ifndef _ASM_LOONGARCH_QSPINLOCK_H |
| 3 | #define _ASM_LOONGARCH_QSPINLOCK_H |
| 4 | |
| 5 | #include <linux/jump_label.h> |
| 6 | |
| 7 | #ifdef CONFIG_PARAVIRT |
| 8 | |
| 9 | DECLARE_STATIC_KEY_FALSE(virt_spin_lock_key); |
| 10 | |
| 11 | #define virt_spin_lock virt_spin_lock |
| 12 | |
| 13 | static inline bool virt_spin_lock(struct qspinlock *lock) |
| 14 | { |
| 15 | int val; |
| 16 | |
| 17 | if (!static_branch_unlikely(&virt_spin_lock_key)) |
| 18 | return false; |
| 19 | |
| 20 | /* |
| 21 | * On hypervisors without PARAVIRT_SPINLOCKS support we fall |
| 22 | * back to a Test-and-Set spinlock, because fair locks have |
| 23 | * horrible lock 'holder' preemption issues. |
| 24 | */ |
| 25 | |
| 26 | __retry: |
| 27 | val = atomic_read(&lock->val); |
| 28 | |
| 29 | if (val || !atomic_try_cmpxchg(&lock->val, &val, _Q_LOCKED_VAL)) { |
| 30 | cpu_relax(); |
| 31 | goto __retry; |
| 32 | } |
| 33 | |
| 34 | return true; |
| 35 | } |
| 36 | |
| 37 | #endif /* CONFIG_PARAVIRT */ |
| 38 | |
| 39 | #include <asm-generic/qspinlock.h> |
| 40 | |
| 41 | #endif // _ASM_LOONGARCH_QSPINLOCK_H |
| 42 |
Warning: This file is not a C or C++ file. It does not have highlighting.