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SMP: Fix some errors when removing a trask from the assigned task list

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This commit is contained in:
Gregory Nutt 2016-03-22 11:08:30 -06:00
parent 4b18b8d1e3
commit 3b2e94e1fd
1 changed files with 58 additions and 19 deletions
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77
sched/sched/sched_removereadytorun.c
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@ -89,10 +89,10 @@ bool sched_removereadytorun(FAR struct tcb_s *rtcb)
* after the TCB being removed.
*/
FAR struct tcb_s *ntcb = (FAR struct tcb_s *)rtcb->flink;
DEBUGASSERT(ntcb != NULL);
FAR struct tcb_s *nxttcb = (FAR struct tcb_s *)rtcb->flink;
DEBUGASSERT(nxttcb != NULL);
ntcb->task_state = TSTATE_TASK_RUNNING;
nxttcb->task_state = TSTATE_TASK_RUNNING;
doswitch = true;
}
@ -161,15 +161,16 @@ bool sched_removereadytorun(FAR struct tcb_s *rtcb)
if (rtcb->blink == NULL && TLIST_ISRUNNABLE(rtcb->task_state))
{
FAR struct tcb_s *ntcb;
FAR struct tcb_s *nxttcb;
FAR struct tcb_s *rtrtcb;
int me;
/* There must always be at least one task in the list (the IDLE task)
* after the TCB being removed.
*/
ntcb = (FAR struct tcb_s *)rtcb->flink;
DEBUGASSERT(ntcb != NULL);
nxttcb = (FAR struct tcb_s *)rtcb->flink;
DEBUGASSERT(nxttcb != NULL);
/* If we are modifying the head of some assigned task list other than
* our own, we will need to stop that CPU.
@ -181,11 +182,57 @@ bool sched_removereadytorun(FAR struct tcb_s *rtcb)
DEBUGVERIFY(up_cpu_pause(cpu));
}
/* The task is running but the CPU that it was running on has been
* paused. We can now safely remove its TCB from the ready-to-run
* task list. In the SMP case this may be either the g_readytorun()
* or the g_assignedtasks[cpu] list.
*/
dq_rem((FAR dq_entry_t *)rtcb, tasklist);
/* Which task will go at the head of the list? It will be either the
* next tcb in the assigned task list (nxttcb) or a TCB in the
* g_readytorun list. We can only select a task from that list if
* the affinity mask includes the current CPU.
*
* REVISIT: What should we do, if anything, if pre-emption is locked
* by the another CPU? Should just used nxttcb? Should we select
* from the pending task list instead of the g_readytorun list?
*/
for (rtrtcb = (FAR struct tcb_s *)g_readytorun.head;
rtrtcb != NULL && !CPU_ISSET(cpu, &rtrtcb->affinity);
rtrtcb = (FAR struct tcb_s *)rtrtcb->flink);
/* Did we find a task in the g_readytorun list? Which task should
* we use? We decide strictly by the priority of the two tasks.
*/
if (rtrtcb != NULL && rtrtcb->sched_priority >= nxttcb->sched_priority)
{
FAR struct tcb_s *tmptcb;
/* The TCB at the head of the ready to run list has the higher
* priority. Remove that task from the head of the g_readytorun
* list and add to the head of the g_assignedtasks[cpu] list.
*/
tmptcb = (FAR struct tcb_s *)
dq_remfirst((FAR dq_queue_t *)&g_readytorun);
DEBUGASSERT(tmptcb == rtrtcb);
dq_addfirst((FAR dq_entry_t *)tmptcb, tasklist);
tmptcb->cpu = cpu;
nxttcb = tmptcb;
}
/* Will pre-emption be disabled after the switch? If the lockcount is
* greater than zero, then this task/this CPU holds the scheduler lock.
*/
if (ntcb->lockcount > 0)
if (nxttcb->lockcount > 0)
{
/* Yes... make sure that scheduling logic knows about this */
@ -204,7 +251,7 @@ bool sched_removereadytorun(FAR struct tcb_s *rtcb)
* than zero, then this task/this CPU holds the IRQ lock
*/
if (ntcb->irqcount > 0)
if (nxttcb->irqcount > 0)
{
/* Yes... make sure that scheduling logic knows about this */
@ -213,21 +260,13 @@ bool sched_removereadytorun(FAR struct tcb_s *rtcb)
}
else
{
/* No.. we may need to perform release our hold on the lock. */
/* No.. we may need to perform release our hold on the irq state. */
spin_setbit(&g_cpu_irqset, cpu, &g_cpu_irqsetlock,
spin_clrbit(&g_cpu_irqset, cpu, &g_cpu_irqsetlock,
&g_cpu_irqlock);
}
ntcb->task_state = TSTATE_TASK_RUNNING;
/* The task is running but the CPU that it was running on has been
* paused. We can now safely remove its TCB from the ready-to-run
* task list. In the SMP case this may be either the g_readytorun()
* or the g_assignedtasks[cpu] list.
*/
dq_rem((FAR dq_entry_t *)rtcb, tasklist);
nxttcb->task_state = TSTATE_TASK_RUNNING;
/* All done, restart the other CPU (if it was paused). */