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sched/semaphore/sem_holder.c: Fix a bad assertion. The comments state correctly that we cannot make any assumptions about the number of holders of the semaphore, yet the code asserts if there are any holders. This makes the code behave closer to what the comments say.

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Gregory Nutt 2019-06-28 21:47:32 -06:00
parent f4a21af755
commit df3ea977bf
1 changed files with 23 additions and 17 deletions
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40
sched/semaphore/sem_holder.c
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@ -1,7 +1,7 @@
/****************************************************************************
* sched/semaphore/sem_holder.c
*
* Copyright (C) 2009-2011, 2013, 2016-2018 Gregory Nutt. All rights
* Copyright (C) 2009-2011, 2013, 2016-2019 Gregory Nutt. All rights
* reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
@ -876,7 +876,7 @@ void nxsem_initholders(void)
* Name: nxsem_destroyholder
*
* Description:
* Called from nxsem_destroyholder() to handle any holders of a semaphore
* Called from nxsem_destroy() to handle any holders of a semaphore
* when it is destroyed.
*
* Input Parameters:
@ -891,31 +891,37 @@ void nxsem_initholders(void)
void nxsem_destroyholder(FAR sem_t *sem)
{
/* It is an error if a semaphore is destroyed while there are any holders
* (except perhaps the thread release the semaphore itself). Hmmm.. but
* we actually have to assume that the caller knows what it is doing because
* could have killed another thread that is the actual holder of the semaphore.
* We cannot make any assumptions about the state of the semaphore or the
* state of any of the holder threads.
/* It might be an error if a semaphore is destroyed while there are any
* holders of the semaphore (except perhaps the thread that release the
* semaphore itself). We actually have to assume that the caller knows
* what it is doing because could have killed another thread that is the
* actual holder of the semaphore.
*
* So just recover any stranded holders and hope the task knows what it is
* doing.
* It is also a standard practice to destroy the semaphore while the
* caller holds it. Of course, the caller MUST assure that there are no
* other holders of the semaphore in this case. This occurs, for example,
* when a driver is unlink'ed and the driver instance must be destroyed.
*
* Therefore, we cannot make any assumptions about the state of the
* semaphore or the state of any of the holder threads. So just recover
* any stranded holders and hope the task knows what it is doing.
*/
#if CONFIG_SEM_PREALLOCHOLDERS > 0
if (sem->hhead != NULL)
{
serr("ERROR: Semaphore destroyed with holders\n");
DEBUGPANIC();
/* There may be an issue if there are multiple holders of
* the semaphore.
*/
DEBUGASSERT(sem->hhead->flink == NULL);
(void)nxsem_foreachholder(sem, nxsem_recoverholders, NULL);
}
#else
if (sem->holder[0].htcb != NULL || sem->holder[1].htcb != NULL)
{
serr("ERROR: Semaphore destroyed with holder\n");
DEBUGPANIC();
}
/* There may be an issue if there are multiple holders of the semaphore. */
DEBUGASSERT(sem->holder[0].htcb == NULL || sem->holder[1].htcb == NULL);
sem->holder[0].htcb = NULL;
sem->holder[1].htcb = NULL;