Re: [PATCH] ifcvf: move IRQ request/free to status change handlers

[Jason Wang <jasowang@xxxxxxxxxx>]

On 2020/5/11 下午6:18, Francesco Lavra wrote:
> On 5/11/20 11:26 AM, Jason Wang wrote:
> > On 2020/5/11 下午3:19, Zhu Lingshan wrote:
> > > This commit move IRQ request and free operations from probe()
> > > to VIRTIO status change handler to comply with VIRTIO spec.
> > >
> > > VIRTIO spec 1.1, section 2.1.2 Device Requirements: Device Status Field
> > > The device MUST NOT consume buffers or send any used buffer
> > > notifications to the driver before DRIVER_OK.
> >
> >
> > My previous explanation might be wrong here. It depends on how you 
> > implement your hardware, if you hardware guarantee that no interrupt 
> > will be triggered before DRIVER_OK, then it's fine.
> >
> > And the main goal for this patch is to allocate the interrupt on demand.
> >
> >
> > > Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> > > ---
> > >   drivers/vdpa/ifcvf/ifcvf_main.c | 119 
> > > ++++++++++++++++++++++++----------------
> > >   1 file changed, 73 insertions(+), 46 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
> > > b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > index abf6a061..4d58bf2 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > @@ -28,6 +28,60 @@ static irqreturn_t ifcvf_intr_handler(int irq, 
> > > void *arg)
> > >       return IRQ_HANDLED;
> > >   }
> > > +static void ifcvf_free_irq_vectors(void *data)
> > > +{
> > > +    pci_free_irq_vectors(data);
> > > +}
> > > +
> > > +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > +{
> > > +    struct pci_dev *pdev = adapter->pdev;
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +    int i;
> > > +
> > > +
> > > +    for (i = 0; i < queues; i++)
> > > +        devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > +
> > > +    ifcvf_free_irq_vectors(pdev);
> > > +}
> > > +
> > > +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +    struct pci_dev *pdev = adapter->pdev;
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +    int vector, i, ret, irq;
> > > +
> > > +    ret = pci_alloc_irq_vectors(pdev, IFCVF_MAX_INTR,
> > > +                    IFCVF_MAX_INTR, PCI_IRQ_MSIX);
> > > +    if (ret < 0) {
> > > +        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> > > +        return ret;
> > > +    }
> > > +
> > > +    for (i = 0; i < IFCVF_MAX_QUEUE_PAIRS * 2; i++) {
> > > +        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> > > +             pci_name(pdev), i);
> > > +        vector = i + IFCVF_MSI_QUEUE_OFF;
> > > +        irq = pci_irq_vector(pdev, vector);
> > > +        ret = devm_request_irq(&pdev->dev, irq,
> > > +                       ifcvf_intr_handler, 0,
> > > +                       vf->vring[i].msix_name,
> > > +                       &vf->vring[i]);
> > > +        if (ret) {
> > > +            IFCVF_ERR(pdev,
> > > +                  "Failed to request irq for vq %d\n", i);
> > > +            ifcvf_free_irq(adapter, i);
> >
> >
> > I'm not sure this unwind is correct. It looks like we should loop and 
> > call devm_free_irq() for virtqueue [0, i);
>
> That's exactly what the code does: ifcvf_free_irq() contains a (i = 0; 
> i < queues; i++) loop, and here the function is called with the 
> `queues` argument set to `i`.

Oh right.

Thanks