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c23b129e55
Now we halt CPU cores that are going to be idle for a lengthy period, we don't need to try to save power in other ways. And anyway, this was not very effective.
56 lines
1020 B
C
56 lines
1020 B
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef SPINLOCK_H
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#define SPINLOCK_H
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/*
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* Provides a lightweight mutex synchronisation primitive.
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*
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* Copyright (C) 2020 Martin Whitaker.
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*/
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#include <stdbool.h>
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/*
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* A mutex object. Use spin_unlock() to initialise prior to first use.
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*/
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typedef volatile bool spinlock_t;
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/*
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* Spins until the mutex is unlocked.
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*/
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static inline void spin_wait(spinlock_t *lock)
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{
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if (lock) {
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while (*lock) {
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__builtin_ia32_pause();
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}
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}
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}
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/*
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* Spins until the mutex is unlocked, then locks the mutex.
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*/
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static inline void spin_lock(spinlock_t *lock)
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{
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if (lock) {
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while (!__sync_bool_compare_and_swap(lock, false, true)) {
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do {
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__builtin_ia32_pause();
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} while (*lock);
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}
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__sync_synchronize();
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}
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}
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/*
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* Unlocks the mutex.
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*/
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static inline void spin_unlock(spinlock_t *lock)
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{
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if (lock) {
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__sync_synchronize();
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*lock = false;
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}
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}
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#endif // SPINLOCK_H
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