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Sempahores: Add logic to clean up after task_delete() or pthread_cancel() if the task happens to be waiting on a semaphore when it is cancelled

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This commit is contained in:
Gregory Nutt 2014-12-13 12:02:25 -06:00
parent c1a8d46539
commit b3a1939020
7 changed files with 305 additions and 23 deletions
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2
sched/semaphore/Make.defs
View file

@ -34,7 +34,7 @@
############################################################################
CSRCS += sem_destroy.c sem_wait.c sem_trywait.c sem_timedwait.c
CSRCS += sem_post.c
CSRCS += sem_post.c sem_recover.c
ifneq ($(CONFIG_DISABLE_SIGNALS),y)
CSRCS += sem_waitirq.c

148
sched/semaphore/sem_recover.c Normal file
View file

@ -0,0 +1,148 @@
/****************************************************************************
* sched/semaphore/sem_recover.c
*
* Copyright (C) 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/arch.h>
#include <nuttx/sched.h>
#include "semaphore/semaphore.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: sem_recover
*
* Description:
* This function is called from task_recover() when a task is deleted via
* task_delete() or via pthread_cancel(). It current only checks on the
* case where a task is waiting for semaphore at the time that is was
* killed.
*
* REVISIT: A more complete implementation would release counts on all
* semaphores held by the thread. That would, however, require some
* significant extension to the semaphore data structures because given
* only the task, there is not mechanism to traverse all of the semaphores
* with counts held by the task.
*
* Inputs:
* tcb - The TCB of the terminated task or thread
*
* Return Value:
* None.
*
* Assumptions:
* This function is called from task deletion logic in a safe context.
*
****************************************************************************/
void sem_recover(FAR struct tcb_s *tcb)
{
irqstate_t flags;
/* The task is being deleted. If it is waiting for a semphore, then
* increment the count on the semaphores. This logic is almost identical
* to what you see in sem_waitirq() except that no attempt is made to
* restart the exiting task.
*
* NOTE: In the case that the task is waiting we can assume: (1) That the
* task state is TSTATE_WAIT_SEM and (2) that the 'waitsem' in the TCB is
* non-null. If we get here via pthread_cancel() or via task_delete(),
* then the task state should be preserved; it will be altered in other
* cases but in those cases waitsem should be NULL anyway (but we do not
* enforce that here).
*/
flags = irqsave();
if (tcb->task_state == TSTATE_WAIT_SEM)
{
sem_t *sem = tcb->waitsem;
DEBUGASSERT(sem != NULL && sem->semcount < 0);
/* Restore the correct priority of all threads that hold references
* to this semaphore.
*/
sem_canceled(tcb, sem);
/* And increment the count on the semaphore. This releases the count
* that was taken by sem_post(). This count decremented the semaphore
* count to negative and caused the thread to be blocked in the first
* place.
*/
sem->semcount++;
/* Clear the semaphore to assure that it is not reused. But leave the
* state as TSTATE_WAIT_SEM. This is necessary because this is a
* necessary indication that the TCB still resides in the waiting-for-
* semaphore list.
*/
tcb->waitsem = NULL;
}
irqrestore(flags);
}

4
sched/semaphore/semaphore.h
View file

@ -85,6 +85,10 @@ void sem_initialize(void);
void sem_waitirq(FAR struct tcb_s *wtcb, int errcode);
#endif
/* Recover semaphore resources with a task or thread is destroyed */
void sem_recover(FAR struct tcb_s *tcb);
/* Special logic needed only by priority inheritance to manage collections of
* holders of semaphores.
*/

35
sched/task/task_recover.c
View file

@ -43,11 +43,13 @@
#include <nuttx/wdog.h>
#include <nuttx/sched.h>
#include "semaphore/semaphore.h"
#include "wdog/wdog.h"
#include "mqueue/mqueue.h"
#include "task/task.h"
/****************************************************************************
* Definitions
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
@ -78,9 +80,9 @@
* Name: task_recover
*
* Description:
* This function is called when a task is deleted via task_deleted or
* via pthread_cancel. I checks if the task was waiting for a message
* queue event and adjusts counts appropriately.
* This function is called when a task is deleted via task_delete() or
* via pthread_cancel. I checks checks for semaphores, message queue, and
* watchdog timer resources stranded in bad conditions.
*
* Inputs:
* tcb - The TCB of the terminated task or thread
@ -95,28 +97,19 @@
void task_recover(FAR struct tcb_s *tcb)
{
irqstate_t flags;
/* The task is being deleted. Cancel in pending timeout events. */
/* The task is being deleted. If it is waiting for any timed event, then
* tcb->waitdog will be non-NULL. Cancel the watchdog now so that no
* events occur after the watchdog expires. Obviously there are lots of
* race conditions here so this will most certainly have to be revisited in
* the future.
wd_recover(tcb);
/* If the thread holds semaphore counts or is waiting for a semaphore count,
* then release the counts.
*/
flags = irqsave();
if (tcb->waitdog)
{
(void)wd_cancel(tcb->waitdog);
(void)wd_delete(tcb->waitdog);
tcb->waitdog = NULL;
}
irqrestore(flags);
/* Handle cases where the thread was waiting for a message queue event */
sem_recover(tcb);
#ifndef CONFIG_DISABLE_MQUEUE
/* Handle cases where the thread was waiting for a message queue event */
mq_recover(tcb);
#endif
}

2
sched/wdog/Make.defs
View file

@ -34,7 +34,7 @@
############################################################################
CSRCS += wd_initialize.c wd_create.c wd_start.c wd_cancel.c wd_delete.c
CSRCS += wd_gettime.c
CSRCS += wd_gettime.c wd_recover.c
# Include wdog build support

115
sched/wdog/wd_recover.c Normal file
View file

@ -0,0 +1,115 @@
/****************************************************************************
* sched/wdog/wdog_recover.c
*
* Copyright (C) 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/arch.h>
#include <nuttx/wdog.h>
#include <nuttx/sched.h>
#include "wdog/wdog.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: wd_recover
*
* Description:
* This function is called from task_recover() when a task is deleted via
* task_delete() or via pthread_cancel(). It checks if the deleted task
* is waiting for a timed event and if so cancels the timeout
*
* Inputs:
* tcb - The TCB of the terminated task or thread
*
* Return Value:
* None.
*
* Assumptions:
* This function is called from task deletion logic in a safe context.
*
****************************************************************************/
void wd_recover(FAR struct tcb_s *tcb)
{
irqstate_t flags;
/* The task is being deleted. If it is waiting for any timed event, then
* tcb->waitdog will be non-NULL. Cancel the watchdog now so that no
* events occur after the watchdog expires. Obviously there are lots of
* race conditions here so this will most certainly have to be revisited in
* the future.
*/
flags = irqsave();
if (tcb->waitdog)
{
(void)wd_cancel(tcb->waitdog);
(void)wd_delete(tcb->waitdog);
tcb->waitdog = NULL;
}
irqrestore(flags);
}

22
sched/wdog/wdog.h
View file

@ -144,6 +144,28 @@ unsigned int wd_timer(int ticks);
void wd_timer(void);
#endif
/****************************************************************************
* Name: wd_recover
*
* Description:
* This function is called from task_recover() when a task is deleted via
* task_delete() or via pthread_cancel(). It checks if the deleted task
* is waiting for a timed event and if so cancels the timeout
*
* Inputs:
* tcb - The TCB of the terminated task or thread
*
* Return Value:
* None.
*
* Assumptions:
* This function is called from task deletion logic in a safe context.
*
****************************************************************************/
struct tcb_s;
void wd_recover(FAR struct tcb_s *tcb);
#undef EXTERN
#ifdef __cplusplus
}