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Diffstat (limited to 'nuttx/sched/sched_addreadytorun.c')
-rw-r--r-- | nuttx/sched/sched_addreadytorun.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/nuttx/sched/sched_addreadytorun.c b/nuttx/sched/sched_addreadytorun.c new file mode 100644 index 000000000..f6117b6ff --- /dev/null +++ b/nuttx/sched/sched_addreadytorun.c @@ -0,0 +1,149 @@ +/**************************************************************************** + * sched/sched_addreadytorun.c + * + * Copyright (C) 2007-2009 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 <stdbool.h> +#include <queue.h> +#include <assert.h> + +#include "os_internal.h" + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Type Declarations + ****************************************************************************/ + +/**************************************************************************** + * Global Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: sched_addreadytorun + * + * Description: + * This function adds a TCB to the ready to run + * list. If the currently active task has preemption disabled + * and the new TCB would cause this task to be preempted, the + * new task is added to the g_pendingtasks list instead. The + * pending tasks will be made ready-to-run when preemption + * is unlocked. + * + * Inputs: + * btcb - Points to the blocked TCB that is ready-to-run + * + * Return Value: + * true if the currently active task (the head of the + * g_readytorun list) has changed. + * + * Assumptions: + * - The caller has established a critical section before + * calling this function (calling sched_lock() first is NOT + * a good idea -- use irqsave()). + * - The caller has already removed the input rtcb from + * whatever list it was in. + * - The caller handles the condition that occurs if the + * the head of the g_readytorun list is changed. + * + ****************************************************************************/ + +bool sched_addreadytorun(FAR _TCB *btcb) +{ + FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head; + bool ret; + + /* Check if pre-emption is disabled for the current running task and if + * the new ready-to-run task would cause the current running task to be + * preempted. + */ + + if (rtcb->lockcount && rtcb->sched_priority < btcb->sched_priority) + { + /* Yes. Preemption would occur! Add the new ready-to-run task to the + * g_pendingtasks task list for now. + */ + + sched_addprioritized(btcb, (FAR dq_queue_t*)&g_pendingtasks); + btcb->task_state = TSTATE_TASK_PENDING; + ret = false; + } + + /* Otherwise, add the new task to the g_readytorun task list */ + + else if (sched_addprioritized(btcb, (FAR dq_queue_t*)&g_readytorun)) + { + /* Information the instrumentation logic that we are switching tasks */ + + sched_note_switch(rtcb, btcb); + + /* The new btcb was added at the head of the g_readytorun list. It + * is now to new active task! + */ + + ASSERT(!rtcb->lockcount && btcb->flink != NULL); + + btcb->task_state = TSTATE_TASK_RUNNING; + btcb->flink->task_state = TSTATE_TASK_READYTORUN; + ret = true; + } + else + { + /* The new btcb was added in the middle of the g_readytorun list */ + + btcb->task_state = TSTATE_TASK_READYTORUN; + ret = false; + } + + return ret; +} |