b6693065e7
For programs with the dependencies logic in pthread_once callback , using global locks may cause deadlock:
task A
pthread_once()
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|-> nxrmutex_lock(&g_lock);
-> init_routine(); // callback to wait task B
task B
pthread_once()
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->nxrmutex_lock(&g_lock); // Deadlock
->init_routine(); // hold resource to wake up task A
Signed-off-by: hujun5 <hujun5@xiaomi.com>
91 lines
2.9 KiB
C
91 lines
2.9 KiB
C
/****************************************************************************
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* libs/libc/pthread/pthread_once.c
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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 <errno.h>
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#include <stdbool.h>
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#include <pthread.h>
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#include <nuttx/mutex.h>
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#include <debug.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: pthread_once
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*
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* Description:
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* The first call to pthread_once() by any thread with a given
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* once_control, will call the init_routine with no arguments. Subsequent
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* calls to pthread_once() with the same once_control will have no effect.
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* On return from pthread_once(), init_routine will have completed.
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*
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* Input Parameters:
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* once_control - Determines if init_routine should be called.
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* once_control should be declared and initialized as follows:
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*
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* pthread_once_t once_control = PTHREAD_ONCE_INIT;
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*
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* PTHREAD_ONCE_INIT is defined in pthread.h
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* init_routine - The initialization routine that will be called once.
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*
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* Returned Value:
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* 0 (OK) on success or an error number shall be returned to
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* indicate the error.
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*
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* Assumptions:
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*
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****************************************************************************/
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int pthread_once(FAR pthread_once_t *once_control,
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CODE void (*init_routine)(void))
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{
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/* Sanity checks */
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if (once_control == NULL || init_routine == NULL)
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{
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return EINVAL;
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}
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if (!once_control->done)
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{
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pthread_mutex_lock(&once_control->mutex);
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if (!once_control->done)
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{
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/* Call the init_routine with pre-emption enabled. */
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init_routine();
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once_control->done = true;
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}
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pthread_mutex_unlock(&once_control->mutex);
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}
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return OK;
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}
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