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f4122d99c5
Replace the BSD-3-Clause boiler plate license text with an SPDX tag. Fixes: #189 Signed-off-by: David B. Kinder <david.b.kinder@intel.com>
36 lines
808 B
C
36 lines
808 B
C
/*
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* Copyright (C) 2018 Intel Corporation. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <hv_lib.h>
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inline int spinlock_init(spinlock_t *lock)
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{
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memset(lock, 0, sizeof(spinlock_t));
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return 0;
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}
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int spinlock_obtain(spinlock_t *lock)
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{
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/* The lock function atomically increments and exchanges the head
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* counter of the queue. If the old head of the queue is equal to the
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* tail, we have locked the spinlock. Otherwise we have to wait.
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*/
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asm volatile (" lock xaddl %%eax,%[head]\n"
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" cmpl %%eax,%[tail]\n"
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" jz 1f\n"
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"2: pause\n"
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" cmpl %%eax,%[tail]\n"
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" jnz 2b\n"
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"1:\n"
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:
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: "a" (1),
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[head] "m"(lock->head),
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[tail] "m"(lock->tail)
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: "cc", "memory");
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return 0;
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}
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