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
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