341 lines
11 KiB
C
341 lines
11 KiB
C
/****************************************************************************
|
|
* sched/work/work_inherit.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 <sched.h>
|
|
|
|
#include <nuttx/wqueue.h>
|
|
|
|
#include "sched/sched.h"
|
|
#include "wqueue/wqueue.h"
|
|
|
|
#if defined(CONFIG_SCHED_WORKQUEUE) && defined(CONFIG_SCHED_LPWORK) && \
|
|
defined(CONFIG_PRIORITY_INHERITANCE)
|
|
|
|
/****************************************************************************
|
|
* Private Data
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: lpwork_boostpriority
|
|
*
|
|
* Description:
|
|
* Called by the work queue client to assure that the priority of the low-
|
|
* priority worker thread is at least at the requested level, reqprio. This
|
|
* function would normally be called just before calling work_queue().
|
|
*
|
|
* Parameters:
|
|
* reqprio - Requested minimum worker thread priority
|
|
*
|
|
* Return Value:
|
|
* None
|
|
*
|
|
****************************************************************************/
|
|
|
|
void lpwork_boostpriority(uint8_t reqprio)
|
|
{
|
|
FAR struct tcb_s *wtcb;
|
|
irqstate_t flags;
|
|
pid_t wpid;
|
|
|
|
/* Clip to the configured maximum priority */
|
|
|
|
if (reqprio > CONFIG_SCHED_LPWORKPRIOMAX)
|
|
{
|
|
reqprio = CONFIG_SCHED_LPWORKPRIOMAX;
|
|
}
|
|
|
|
/* Get the process ID of the low priority worker thread from the low
|
|
* priority work queue. Then get the TCB of the low priority worker
|
|
* thread from the process ID.
|
|
*/
|
|
|
|
wpid = g_lpwork.pid;
|
|
wtcb = sched_gettcb(wpid);
|
|
|
|
/* Prevent context switches until we get the priorities right */
|
|
|
|
flags = irqsave();
|
|
sched_lock();
|
|
|
|
#if CONFIG_SEM_NNESTPRIO > 0
|
|
/* If the priority of the client thread that is greater than the base
|
|
* priority of the worker thread, then we may need to adjust the worker
|
|
* thread's priority now or later to that priority.
|
|
*/
|
|
|
|
if (reqprio > wtcb->base_priority)
|
|
{
|
|
/* If the new priority is greater than the current, possibly already
|
|
* boosted priority of the worker thread, then we will have to raise
|
|
* the worker thread's priority now.
|
|
*/
|
|
|
|
if (reqprio > wtcb->sched_priority)
|
|
{
|
|
/* If the current priority of worker thread has already been
|
|
* boosted, then add the boost priority to the list of restoration
|
|
* priorities. When the higher priority waiter thread gets its
|
|
* count, then we need to revert the worker thread to this saved
|
|
* priority (not to its base priority).
|
|
*/
|
|
|
|
if (wtcb->sched_priority > wtcb->base_priority)
|
|
{
|
|
/* Save the current, boosted priority of the worker thread. */
|
|
|
|
if (wtcb->npend_reprio < CONFIG_SEM_NNESTPRIO)
|
|
{
|
|
wtcb->pend_reprios[wtcb->npend_reprio] = wtcb->sched_priority;
|
|
wtcb->npend_reprio++;
|
|
}
|
|
}
|
|
|
|
/* Raise the priority of the worker. This cannot cause a context
|
|
* switch because we have preemption disabled. The worker thread
|
|
* may be marked "pending" and the switch may occur during
|
|
* sched_unblock() processing.
|
|
*/
|
|
|
|
(void)sched_setpriority(wtcb, reqprio);
|
|
}
|
|
else
|
|
{
|
|
/* The new priority is above the base priority of the worker,
|
|
* but not as high as its current working priority. Just put it
|
|
* in the list of pending restoration priorities so that when the
|
|
* higher priority thread gets its count, we can revert to this
|
|
* saved priority and not to the base priority.
|
|
*/
|
|
|
|
wtcb->pend_reprios[wtcb->npend_reprio] = reqprio;
|
|
wtcb->npend_reprio++;
|
|
}
|
|
}
|
|
#else
|
|
/* If the priority of the client thread that is less than of equal to the
|
|
* priority of the worker thread, then do nothing because the thread is
|
|
* already running at a sufficient priority.
|
|
*/
|
|
|
|
if (reqprio > wtcb->sched_priority)
|
|
{
|
|
/* Raise the priority of the worker thread. This cannot cause
|
|
* context switch because we have preemption disabled. The task
|
|
* will be marked "pending" and the switch will occur during
|
|
* sched_unlock() processing.
|
|
*/
|
|
|
|
(void)sched_setpriority(wtcb, reqprio);
|
|
}
|
|
#endif
|
|
|
|
sched_unlock();
|
|
irqrestore(flags);
|
|
}
|
|
|
|
/****************************************************************************
|
|
* Name: lpwork_restorepriority
|
|
*
|
|
* Description:
|
|
* This function is called to restore the priority after it was previously
|
|
* boosted. This is often done by client logic on the worker thread when
|
|
* the scheduled work completes. It will check if we need to drop the
|
|
* priority of the worker thread.
|
|
*
|
|
* Parameters:
|
|
* reqprio - Previously requested minimum worker thread priority to be
|
|
* "unboosted"
|
|
*
|
|
* Return Value:
|
|
* None
|
|
*
|
|
****************************************************************************/
|
|
|
|
void lpwork_restorepriority(uint8_t reqprio)
|
|
{
|
|
FAR struct tcb_s *wtcb;
|
|
irqstate_t flags;
|
|
pid_t wpid;
|
|
uint8_t wpriority;
|
|
int index;
|
|
int selected;
|
|
|
|
/* Clip to the configured maximum priority */
|
|
|
|
if (reqprio > CONFIG_SCHED_LPWORKPRIOMAX)
|
|
{
|
|
reqprio = CONFIG_SCHED_LPWORKPRIOMAX;
|
|
}
|
|
|
|
/* Get the process ID of the low priority worker thread from the low
|
|
* priority work queue. Then get the TCB of the low priority worker
|
|
* thread from the process ID.
|
|
*/
|
|
|
|
wpid = g_lpwork.pid;
|
|
wtcb = sched_gettcb(wpid);
|
|
|
|
/* Prevent context switches until we get the priorities right */
|
|
|
|
flags = irqsave();
|
|
sched_lock();
|
|
|
|
/* Was the priority of the worker thread boosted? If so, then drop its
|
|
* priority back to the correct level. What is the correct level?
|
|
*/
|
|
|
|
if (wtcb->sched_priority != wtcb->base_priority)
|
|
{
|
|
#if CONFIG_SEM_NNESTPRIO > 0
|
|
/* Are there other, pending priority levels to revert to? */
|
|
|
|
if (wtcb->npend_reprio < 1)
|
|
{
|
|
/* No... the worker thread has only been boosted once.
|
|
* npend_reprio should be 0 and the boosted priority should be the
|
|
* priority of the client task (reqprio)
|
|
*
|
|
* That latter assumption may not be true if the client's priority
|
|
* was also boosted so that it no longer matches the wtcb's
|
|
* sched_priority. Or if CONFIG_SEM_NNESTPRIO is too small (so
|
|
* that we do not have a proper record of the reprioritizations).
|
|
*/
|
|
|
|
DEBUGASSERT(/* wtcb->sched_priority == reqprio && */
|
|
wtcb->npend_reprio == 0);
|
|
|
|
/* Reset the worker's priority back to the base priority. */
|
|
|
|
sched_reprioritize(wtcb, wtcb->base_priority);
|
|
}
|
|
|
|
/* There are multiple pending priority levels. The worker thread's
|
|
* "boosted" priority could greater than or equal to "reqprio" (it could
|
|
* be greater if its priority we boosted because it also holds some
|
|
* semaphore).
|
|
*/
|
|
|
|
else if (wtcb->sched_priority <= reqprio)
|
|
{
|
|
/* The worker thread has been boosted to the same priority as the
|
|
* waiter thread that just received the count. We will simply
|
|
* reprioritize to the next highest pending priority.
|
|
*/
|
|
|
|
/* Find the highest pending priority and remove it from the list */
|
|
|
|
for (index = 1, selected = 0; index < wtcb->npend_reprio; index++)
|
|
{
|
|
if (wtcb->pend_reprios[index] > wtcb->pend_reprios[selected])
|
|
{
|
|
selected = index;
|
|
}
|
|
}
|
|
|
|
/* Remove the highest priority pending priority from the list */
|
|
|
|
wpriority = wtcb->pend_reprios[selected];
|
|
index = wtcb->npend_reprio - 1;
|
|
if (index > 0)
|
|
{
|
|
wtcb->pend_reprios[selected] = wtcb->pend_reprios[index];
|
|
}
|
|
|
|
wtcb->npend_reprio = index;
|
|
|
|
/* And apply that priority to the thread (while retaining the
|
|
* base_priority)
|
|
*/
|
|
|
|
sched_setpriority(wtcb, wpriority);
|
|
}
|
|
else
|
|
{
|
|
/* The worker thread has been boosted to a higher priority than the
|
|
* waiter task. The pending priority should be in the list (unless
|
|
* it was lost because of of list overflow or because the worker
|
|
* was reprioritized again unbeknownst to the priority inheritance
|
|
* logic).
|
|
*
|
|
* Search the list for the matching priority.
|
|
*/
|
|
|
|
for (index = 0; index < wtcb->npend_reprio; index++)
|
|
{
|
|
/* Does this pending priority match the priority of the thread
|
|
* that just received the count?
|
|
*/
|
|
|
|
if (wtcb->pend_reprios[index] == reqprio)
|
|
{
|
|
/* Yes, remove it from the list */
|
|
|
|
selected = wtcb->npend_reprio - 1;
|
|
if (selected > 0)
|
|
{
|
|
wtcb->pend_reprios[index] = wtcb->pend_reprios[selected];
|
|
}
|
|
|
|
wtcb->npend_reprio = selected;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
#else
|
|
/* There is no alternative restore priorities, drop the priority
|
|
* of the worker thread all the way back to the threads "base"
|
|
* priority.
|
|
*/
|
|
|
|
sched_reprioritize(wtcb, wtcb->base_priority);
|
|
#endif
|
|
}
|
|
|
|
sched_unlock();
|
|
irqrestore(flags);
|
|
}
|
|
|
|
#endif /* CONFIG_SCHED_WORKQUEUE && CONFIG_SCHED_LPWORK && CONFIG_PRIORITY_INHERITANCE */
|