int up_cpu_pause(int cpu)
{
int ret;
#ifdef CONFIG_SCHED_INSTRUMENTATION
/* Notify of the pause event */
sched_note_cpu_pause(this_task(), cpu);
#endif
DEBUGASSERT(cpu >= 0 && cpu < CONFIG_SMP_NCPUS && cpu != this_cpu());
/* Take the both spinlocks. The g_cpu_wait spinlock will prevent the SGI2
* handler from returning until up_cpu_resume() is called; g_cpu_paused
* is a handshake that will prefent this function from returning until
* the CPU is actually paused.
*/
DEBUGASSERT(!spin_islocked(&g_cpu_wait[cpu]) &&
!spin_islocked(&g_cpu_paused[cpu]));
spin_lock(&g_cpu_wait[cpu]);
spin_lock(&g_cpu_paused[cpu]);
/* Execute SGI2 */
ret = xtensa_intercpu_interrupt(cpu, CPU_INTCODE_PAUSE);
if (ret < 0)
{
/* What happened? Unlock the g_cpu_wait spinlock */
spin_unlock(&g_cpu_wait[cpu]);
}
else
{
/* Wait for the other CPU to unlock g_cpu_paused meaning that
* it is fully paused and ready for up_cpu_resume();
*/
spin_lock(&g_cpu_paused[cpu]);
}
spin_unlock(&g_cpu_paused[cpu]);
/* On successful return g_cpu_wait will be locked, the other CPU will be
* spinninf on g_cpu_wait and will not continue until g_cpu_resume() is
* called. g_cpu_paused will be unlocked in any case.
*/
return ret;
}
int up_cpu_resume(int cpu)
{
#ifdef CONFIG_SCHED_INSTRUMENTATION
/* Notify of the resume event */
sched_note_cpu_resume(this_task(), cpu);
#endif
DEBUGASSERT(cpu >= 0 && cpu < CONFIG_SMP_NCPUS && cpu != this_cpu());
/* Release the spinlock. Releasing the spinlock will cause the SGI2
* handler on 'cpu' to continue and return from interrupt to the newly
* established thread.
*/
DEBUGASSERT(spin_islocked(&g_cpu_wait[cpu]) &&
!spin_islocked(&g_cpu_paused[cpu]));
spin_unlock(&g_cpu_wait[cpu]);
return OK;
}
void leave_critical_section(irqstate_t flags)
{
/* Do nothing if called from an interrupt handler */
if (!up_interrupt_context())
{
FAR struct tcb_s *rtcb = this_task();
DEBUGASSERT(rtcb != 0 && rtcb->irqcount > 0);
/* Will we still have interrupts disabled after decrementing the
* count?
*/
if (rtcb->irqcount > 1)
{
/* Yes... make sure that the spinlock is set */
DEBUGASSERT(g_cpu_irqlock == SP_LOCKED);
rtcb->irqcount--;
}
else
{
#ifdef CONFIG_SCHED_INSTRUMENTATION_CSECTION
/* No.. Note that we have entered the critical section */
sched_note_csection(rtcb, false);
#endif
/* Decrement our count on the lock. If all CPUs have released,
* then unlock the spinlock.
*/
rtcb->irqcount = 0;
spin_clrbit(&g_cpu_irqset, this_cpu(), &g_cpu_irqsetlock,
&g_cpu_irqlock);
/* Have all CPUs release the lock? */
if (!spin_islocked(&g_cpu_irqlock))
{
/* Check if there are pending tasks and that pre-emption is
* also enabled.
*/
if (g_pendingtasks.head != NULL && !spin_islocked(&g_cpu_schedlock))
{
/* Release any ready-to-run tasks that have collected in
* g_pendingtasks if the scheduler is not locked.
*
* NOTE: This operation has a very high likelihood of causing
* this task to be switched out!
*/
up_release_pending();
}
}
}
/* Restore the previous interrupt state which may still be interrupts
* disabled (but we don't have a mechanism to verify that now)
*/
up_irq_restore(flags);
}
}
bool up_cpu_pausereq(int cpu)
{
return spin_islocked(&g_cpu_paused[cpu]);
}
