On Thu, Aug 27, 2009 at 07:00:34PM +0930, Rusty Russell wrote:
> On Tue, 25 Aug 2009 09:34:34 pm Michael S. Tsirkin wrote:
> > > That's because we didn't do the request_irq's for the per_vector case,
> > > because
> > > we don't have the names. This is what prevented me from doing a nice
> > > encapsulation.
> >
> > Yes. But let's split free_vectors out into free_msix_vectors and
> > free_intx as well?
>
> Perhaps. Patch welcome :)
Could you put the end result somewhere so I can work on top of it?
> > Yes, I agree, this is good cleanup, structure field names should be
> > desriptive. Are you sure we want to make all local variables named
> > vector renamed to msix_vector though? CodingStyle says local var names
> > should be short ... A couple of ideas below.
>
> msix_vec would work.
Yes, ok.
> But vector for something which isn't always the vector
> is misleading, IMHO.
I think you mean it's isn't always used? It's always a vector ...
> > > - if (vector != VIRTIO_MSI_NO_VECTOR) {
> > > - iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
> > > - vector = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
> > > - if (vector == VIRTIO_MSI_NO_VECTOR) {
> > > + if (msix_vector != VIRTIO_MSI_NO_VECTOR) {
> > > + iowrite16(msix_vector, vp_dev->ioaddr+VIRTIO_MSI_QUEUE_VECTOR);
> > > + msix_vector = ioread16(vp_dev->ioaddr+VIRTIO_MSI_QUEUE_VECTOR);
> >
> > checkpatch will complain that space is lacking around "+".
> > We won't have a problem if we keep it named vector.
>
> Yeah, but OTOH ignoring checkpatch warnings is good for the soul.
>
> > > if (!use_msix) {
> > > /* Old style: one normal interrupt for change and all vqs. */
> > > vp_dev->msix_vectors = 0;
> > > - vp_dev->per_vq_vectors = false;
> >
> > I know it's enough to look at msix_vectors, but isn't
> > it cleaner to have per_vq_vectors consistent as well?
> > E.g. del_vqs seems to only look at per_vq_vectors.
>
> This should in fact be:
>
> if (!use_msix) {
> /* Old style: one normal interrupt for change and all vqs. */
> - vp_dev->msix_vectors = 0;
> - vp_dev->per_vq_vectors = false;
> err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
> IRQF_SHARED, dev_name(&vdev->dev), vp_dev);
> - if (!err)
> - vp_dev->intx_enabled = 1;
> - return err;
> + if (err)
> + return err;
> + vp_dev->intx_enabled = 1;
>
>
> The msix fields should all be ignored if msix_enabled is false.
Need to audit code to make sure it's so then. I actually think
per_vq_vectors is kind of not directly tied to msix.
Don't you think it's nicer like del_vqs does:
if (vp_dev->per_vq_vectors) {
}
Than
if (vp_dev->msix_enabled && vp_dev->per_vq_vectors) {
}
BTW, let's get rid of msix_enabled completely?
We can always use msix_vectors ...
> Think about
> running valgrind (or equiv) over the code: if you initialize something which
> shouldn't be accessed, valgrind won't spot it.
>
> For similar reasons, I dislike memseting structs to 0, or kzallocing them.
Yes, I agree generally.
> > > err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
> > > IRQF_SHARED, dev_name(&vdev->dev), vp_dev);
> > > - if (!err)
> > > - vp_dev->intx_enabled = 1;
> > > - return err;
> > > + if (err)
> > > + return err;
> >
> > Maybe move this part out into a separate function? This way
> > vp_try_to_find_vqs does high-level processing.
>
> Nice. Moved this to vp_request_intx().
>
> > > + } else {
> > > + if (per_vq_vectors) {
> > > + /* Best option: one for change interrupt, one per vq. */
> > > + nvectors = 1;
> > > + for (i = 0; i < nvqs; ++i)
> > > + if (callbacks[i])
> > > + ++nvectors;
> > > + } else {
> > > + /* Second best: one for change, shared for all vqs. */
> > > + nvectors = 2;
> >
> > Out of curiosity: why do you put {} here? They aren't
> > strictly necessary ...
>
> Comment made it multiline, looked a bit neater?
>
> Here's the diff result:
Looks good to me. When we are done with cleanups, need to remember to
test this with all the possible combinations: no msix, 2 vectors, 1
vector.
> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
> --- a/drivers/virtio/virtio_pci.c
> +++ b/drivers/virtio/virtio_pci.c
> @@ -346,10 +346,22 @@ error:
> return err;
> }
>
> +static int vp_request_intx(struct virtio_device *vdev)
> +{
> + int err;
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +
> + err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
> + IRQF_SHARED, dev_name(&vdev->dev), vp_dev);
> + if (!err)
> + vp_dev->intx_enabled = 1;
> + return err;
> +}
> +
> static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
> void (*callback)(struct virtqueue *vq),
> const char *name,
> - u16 msix_vector)
> + u16 msix_vec)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> struct virtio_pci_vq_info *info;
> @@ -374,7 +386,7 @@ static struct virtqueue *setup_vq(struct
>
> info->queue_index = index;
> info->num = num;
> - info->msix_vector = msix_vector;
> + info->msix_vector = msix_vec;
>
> size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
> info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
> @@ -398,10 +410,10 @@ static struct virtqueue *setup_vq(struct
> vq->priv = info;
> info->vq = vq;
>
> - if (msix_vector != VIRTIO_MSI_NO_VECTOR) {
> - iowrite16(msix_vector, vp_dev->ioaddr+VIRTIO_MSI_QUEUE_VECTOR);
> - msix_vector = ioread16(vp_dev->ioaddr+VIRTIO_MSI_QUEUE_VECTOR);
> - if (msix_vector == VIRTIO_MSI_NO_VECTOR) {
> + if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
> + iowrite16(msix_vec, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
> + msix_vec = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
> + if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
> err = -EBUSY;
> goto out_assign;
> }
> @@ -479,16 +491,14 @@ static int vp_try_to_find_vqs(struct vir
> bool per_vq_vectors)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> - u16 msix_vector;
> + u16 msix_vec;
> int i, err, nvectors, allocated_vectors;
>
> if (!use_msix) {
> /* Old style: one normal interrupt for change and all vqs. */
> - err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
> - IRQF_SHARED, dev_name(&vdev->dev), vp_dev);
> + err = vp_request_intx(vdev);
> if (err)
> - return err;
> - vp_dev->intx_enabled = 1;
> + goto error_request;
> } else {
> if (per_vq_vectors) {
> /* Best option: one for change interrupt, one per vq. */
> @@ -510,24 +520,24 @@ static int vp_try_to_find_vqs(struct vir
> allocated_vectors = vp_dev->msix_used_vectors;
> for (i = 0; i < nvqs; ++i) {
> if (!callbacks[i] || !vp_dev->msix_enabled)
> - msix_vector = VIRTIO_MSI_NO_VECTOR;
> + msix_vec = VIRTIO_MSI_NO_VECTOR;
> else if (vp_dev->per_vq_vectors)
> - msix_vector = allocated_vectors++;
> + msix_vec = allocated_vectors++;
> else
> - msix_vector = VP_MSIX_VQ_VECTOR;
> - vqs[i] = setup_vq(vdev, i, callbacks[i], names[i], msix_vector);
> + msix_vec = VP_MSIX_VQ_VECTOR;
> + vqs[i] = setup_vq(vdev, i, callbacks[i], names[i], msix_vec);
> if (IS_ERR(vqs[i])) {
> err = PTR_ERR(vqs[i]);
> goto error_find;
> }
> /* allocate per-vq irq if available and necessary */
> if (vp_dev->per_vq_vectors) {
> - snprintf(vp_dev->msix_names[msix_vector],
> + snprintf(vp_dev->msix_names[msix_vec],
> sizeof *vp_dev->msix_names,
> "%s-%s",
> dev_name(&vp_dev->vdev.dev), names[i]);
> - err = request_irq(msix_vector, vring_interrupt, 0,
> - vp_dev->msix_names[msix_vector],
> + err = request_irq(msix_vec, vring_interrupt, 0,
> + vp_dev->msix_names[msix_vec],
> vqs[i]);
> if (err) {
> vp_del_vq(vqs[i]);
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