Re: [PATCH V2 3/6] vDPA: implement IRQ offloading helpers in vDPA core

On 2020/7/21 上午10:02, Zhu, Lingshan wrote:

On 7/20/2020 5:40 PM, Jason Wang wrote:

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On 2020/7/20 下午5:07, Zhu, Lingshan wrote:

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+}
+
+static void vdpa_unsetup_irq(struct vdpa_device *vdev, int qid)
+{
+    struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);
+
+    if (drv->unsetup_vq_irq)
+        drv->unsetup_vq_irq(vdev, qid);

Do you need to check the existence of drv before calling 
unset_vq_irq()?

Yes, we should check this when we take the releasing path into account.

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And how can this synchronize with driver releasing and binding?

Will add an vdpa_unsetup_irq() call in vhsot_vdpa_release().
For binding, I think it is a new dev bound to the the driver,
it should go through the vdpa_setup_irq() routine. or if it is
a device re-bind to vhost_vdpa, I think we have cleaned up
irq_bypass_producer for it as we would call vhdpa_unsetup_irq()
in the release function.

I meant can the following things happen?

1) some vDPA device driver probe the hardware and call 
vdpa_request_irq() in its PCI probe function.
2) vDPA device is probed by vhost-vDPA

Then irq bypass can't work since we when vdpa_unsetup_irq() is 
called, there's no driver bound. Or is there a requirement that 
vdap_request/free_irq() must be called somewhere (e.g in the 
set_status bus operations)? If yes, we need document those requirements.

vdpa_unseup_irq is only called when we want to unregister the producer,

Typo, I meant vdpa_setup_irq().

Thanks

  now we have two code path using it: free_irq and relaase(). I agree we can document this requirements for the helpers, these functions can only be called through status changes(DRIVER_OK and !DRIVER_OK).

Thanks,
BR
Zhu Lingshan

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Thanks