forked from nuttx/nuttx-update
b4def16ac3
`g_iob_sem.semcount` is both manually changed in iob source code and api nxsem_xxx. nxsem related API uses critical_section to ensure sem value is modified correctly. If iob using spin lock and modify sem value in the same time, it's not safe. This PR revert the spin lock change and uses critical section to align with what nxsem uses.
97 lines
3.2 KiB
C
97 lines
3.2 KiB
C
/****************************************************************************
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* mm/iob/iob_free_qentry.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 <assert.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/mm/iob.h>
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#include "iob.h"
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#if CONFIG_IOB_NCHAINS > 0
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: iob_free_qentry
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*
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* Description:
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* Free the I/O buffer chain container by returning it to the free list.
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* The link to the next I/O buffer in the chain is return.
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*
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****************************************************************************/
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FAR struct iob_qentry_s *iob_free_qentry(FAR struct iob_qentry_s *iobq)
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{
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FAR struct iob_qentry_s *nextq = iobq->qe_flink;
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irqstate_t flags;
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/* Free the I/O buffer chain container by adding it to the head of the
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* free or the committed list. We don't know what context we are called
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* from so we use extreme measures to protect the free list: We disable
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* interrupts very briefly.
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*/
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flags = enter_critical_section();
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/* Which list? If there is a task waiting for an IOB chain, then put
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* the IOB chain on either the free list or on the committed list where
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* it is reserved for that allocation (and not available to
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* iob_tryalloc_qentry()).
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*/
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if (g_qentry_sem.semcount < 0)
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{
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iobq->qe_flink = g_iob_qcommitted;
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g_iob_qcommitted = iobq;
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}
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else
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{
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iobq->qe_flink = g_iob_freeqlist;
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g_iob_freeqlist = iobq;
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}
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/* Signal that an I/O buffer chain container is available. If there
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* is a thread waiting for an I/O buffer chain container, this will
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* wake up exactly one thread. The semaphore count will correctly
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* indicated that the awakened task owns an I/O buffer chain container
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* and should find it in the committed list.
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*/
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nxsem_post(&g_qentry_sem);
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leave_critical_section(flags);
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/* And return the I/O buffer chain container after the one that was freed */
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return nextq;
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}
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#endif /* CONFIG_IOB_NCHAINS > 0 */
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