8935ac4cc3
Gregory Nutt has submitted the SGA and we can mograte the licenses to Apache. Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
111 lines
4.0 KiB
C
111 lines
4.0 KiB
C
/****************************************************************************
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* sched/semaphore/sem_recover.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 <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/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_recover
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*
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* Description:
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* This function is called from nxtask_recover() when a task is deleted via
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* task_delete() or via pthread_cancel(). It current only checks on the
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* case where a task is waiting for semaphore at the time that is was
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* killed.
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*
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* REVISIT: A more complete implementation would release counts on all
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* semaphores held by the thread. That would, however, require some
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* significant extension to the semaphore data structures because given
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* only the task, there is not mechanism to traverse all of the semaphores
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* with counts held by the task.
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*
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* Input Parameters:
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* tcb - The TCB of the terminated task or thread
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*
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* Returned Value:
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* None.
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*
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* Assumptions:
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* This function is called from task deletion logic in a safe context.
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*
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****************************************************************************/
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void nxsem_recover(FAR struct tcb_s *tcb)
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{
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irqstate_t flags;
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/* The task is being deleted. If it is waiting for a semaphore, then
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* increment the count on the semaphores. This logic is almost identical
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* to what you see in nxsem_wait_irq() except that no attempt is made to
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* restart the exiting task.
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*
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* NOTE: In the case that the task is waiting we can assume: (1) That the
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* task state is TSTATE_WAIT_SEM and (2) that the 'waitsem' in the TCB is
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* non-null. If we get here via pthread_cancel() or via task_delete(),
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* then the task state should be preserved; it will be altered in other
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* cases but in those cases waitsem should be NULL anyway (but we do not
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* enforce that here).
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*/
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flags = enter_critical_section();
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if (tcb->task_state == TSTATE_WAIT_SEM)
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{
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sem_t *sem = tcb->waitsem;
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DEBUGASSERT(sem != NULL && sem->semcount < 0);
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/* Restore the correct priority of all threads that hold references
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* to this semaphore.
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*/
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nxsem_canceled(tcb, sem);
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/* And increment the count on the semaphore. This releases the count
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* that was taken by sem_wait(). This count decremented the semaphore
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* count to negative and caused the thread to be blocked in the first
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* place.
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*/
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sem->semcount++;
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/* Clear the semaphore to assure that it is not reused. But leave the
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* state as TSTATE_WAIT_SEM. This is necessary because this is a
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* necessary indication that the TCB still resides in the waiting-for-
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* semaphore list.
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*/
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tcb->waitsem = NULL;
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}
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leave_critical_section(flags);
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}
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