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244ab5a3fc
Use atomic type for mutex pointer this is required by the atomic operation. atomic exchange is used to verify the mutex used on condition wait. Signed-off-by: Wendy Liang <wendy.liang@xilinx.com>
41 lines
936 B
C
41 lines
936 B
C
/*
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* Copyright (c) 2016, Xilinx Inc. and Contributors. 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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/*
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* @file generic/condition.c
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* @brief Generic libmetal condition variable handling.
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*/
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#include <metal/condition.h>
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int metal_condition_wait(struct metal_condition *cv,
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metal_mutex_t *m)
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{
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uintptr_t tmpmptr = 0, mptr = (uintptr_t)m;
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int v = 0;
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/* Check if the mutex has been acquired */
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if (!cv || !m || !metal_mutex_is_acquired(m))
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return -EINVAL;
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if (!atomic_compare_exchange_strong(&cv->mptr, &tmpmptr, mptr)) {
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if (tmpmptr != mptr)
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return -EINVAL;
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}
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v = atomic_load(&cv->wakeups);
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atomic_fetch_add(&cv->waiters, 1);
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/* Release the mutex before sleeping. */
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metal_mutex_release(m);
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syscall(SYS_futex, &cv->wakeups, FUTEX_WAIT, v, NULL, NULL, 0);
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atomic_fetch_sub(&cv->waiters, 1);
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/* Acquire the mutex after it's waken up. */
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metal_mutex_acquire(m);
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return 0;
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}
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