Re: [PATCH 01/10] vfio: ccw: Moving state change out of IRQ context

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On 24/04/2018 08:54, Dong Jia Shi wrote:
* Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx> [2018-04-19 16:48:04 +0200]:

[...]

@@ -94,9 +83,15 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
  static void vfio_ccw_sch_irq(struct subchannel *sch)
  {
  	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct irb *irb = this_cpu_ptr(&cio_irb);

  	inc_irq_stat(IRQIO_CIO);
-	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);
+	memcpy(&private->irb, irb, sizeof(*irb));
+
+	WARN_ON(work_pending(&private->io_work));
Hmm, why do we need this?

The current design insure that we have not two concurrent SSCH requests.
How ever I want here to track spurious interrupt.
If we implement cancel, halt or clear requests, we also may trigger (AFAIU)
a second interrupts depending on races between instructions, controller and device.

We do not need it strongly.


+	queue_work(vfio_ccw_work_q, &private->io_work);
+	if (private->completion)
+		complete(private->completion);
  }

  static int vfio_ccw_sch_probe(struct subchannel *sch)
[...]


--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany




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