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d7771b6158
Rename atomic_fetch_add/sub/or/and/xor to atomic_add/sub/or/and/xor to avoid conflicts with the C/C++ standard library naming. The atomic_fetch_xxx naming is reserved by the standard; keeping it causes function name conflicts when source files indirectly include both <nuttx/atomic.h> and <atomic>/<stdatomic.h>. Signed-off-by: zhangyu117 <zhangyu117@xiaomi.com>
137 lines
3.6 KiB
C
137 lines
3.6 KiB
C
/****************************************************************************
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* sched/semaphore/sem_trywait.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdbool.h>
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#include <sched.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/init.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include "sched/sched.h"
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#include "semaphore/semaphore.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsem_trywait_slow
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*
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* Description:
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* This function locks the specified semaphore in slow mode.
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*
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* Input Parameters:
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* sem - the semaphore descriptor
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*
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* Returned Value:
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*
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* EINVAL - Invalid attempt to get the semaphore
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* EAGAIN - The semaphore is not available.
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*
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* Assumptions:
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*
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****************************************************************************/
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int nxsem_trywait_slow(FAR sem_t *sem)
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{
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irqstate_t flags;
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int ret = OK;
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bool mutex = NXSEM_IS_MUTEX(sem);
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FAR atomic_t *val = mutex ? NXSEM_MHOLDER(sem) : NXSEM_COUNT(sem);
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int32_t old;
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int32_t new;
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/* The following operations must be performed with interrupts disabled
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* because sem_post() may be called from an interrupt handler.
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*/
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flags = enter_critical_section();
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/* If the semaphore is available, give it to the requesting task */
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old = atomic_read(val);
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do
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{
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if (mutex)
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{
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if (NXSEM_MACQUIRED(old))
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{
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ret = -EAGAIN;
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break;
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}
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new = NXSEM_MAKE_MHOLDER(nxsched_gettid());
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}
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else
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{
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if (old <= 0)
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{
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ret = -EAGAIN;
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break;
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}
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new = old - 1;
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}
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}
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while (!atomic_try_cmpxchg_acquire(val, &old, new));
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if (ret != -EAGAIN)
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{
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/* It is, let the task take the semaphore */
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#ifdef CONFIG_PRIORITY_PROTECT
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ret = nxsem_protect_wait(sem);
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if (ret < 0)
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{
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if (mutex)
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{
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atomic_set(NXSEM_MHOLDER(sem), NXSEM_NO_MHOLDER);
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}
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else
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{
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atomic_add(NXSEM_COUNT(sem), 1);
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}
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}
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else
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#endif
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{
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if (!mutex)
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{
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nxsem_add_holder(sem);
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}
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}
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}
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/* Interrupts may now be enabled. */
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leave_critical_section(flags);
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return ret;
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}
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