On Tue, Jul 28, 2009 at 12:44:31PM +0930, Rusty Russell wrote:
> On Mon, 27 Jul 2009 01:17:09 am Michael S. Tsirkin wrote:
> > This refactors find_vqs, making it more readable and robust, and fixing
> > two regressions from 2.6.30:
> > - double free_irq causing BUG_ON on device removal
> > - probe failure when vq can't be assigned to msi-x vector
> > (reported on old host kernels)
> >
> > An older version of this patch was tested by Amit Shah.
>
> OK, I've applied both of these; I'd like to see a new test by Amit to
> make sure tho.
>
> I really like this cleanup! I looked harder at this code, and my best
> attempts to untangle it further came to very little. This is what I
> ended up with, but it's all cosmetic and can wait until next merge window.
> See what you think.
>
> Thanks!
> Rusty.
>
> virtio_pci: minor MSI-X cleanups
>
> 1) Rename vp_request_vectors to vp_request_msix_vectors, and take
> non-MSI-X case out to caller.
I'm not sure this change was for the best: we still have a separate code
path under if !use_msix, only in another place now. See below.
And this seems to break the symmetry between request_ and free_vectors.
> 2) Comment weird pci_enable_msix API
> 3) Rename vp_find_vq to setup_vq.
> 4) Fix spaces to tabs
> 5) Make nvectors calc internal to vp_try_to_find_vqs()
The other changes look good to me.
>
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_pci.c | 84 +++++++++++++++++++++++---------------------
> 1 file changed, 45 insertions(+), 39 deletions(-)
>
> 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
> @@ -280,25 +280,14 @@ static void vp_free_vectors(struct virti
> vp_dev->msix_entries = NULL;
> }
>
> -static int vp_request_vectors(struct virtio_device *vdev, int nvectors,
> - bool per_vq_vectors)
> +static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
> + bool per_vq_vectors)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> const char *name = dev_name(&vp_dev->vdev.dev);
> unsigned i, v;
> int err = -ENOMEM;
>
> - if (!nvectors) {
> - /* Can't allocate MSI-X vectors, use regular interrupt */
> - vp_dev->msix_vectors = 0;
> - err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
> - IRQF_SHARED, name, vp_dev);
> - if (err)
> - return err;
> - vp_dev->intx_enabled = 1;
> - return 0;
> - }
> -
> vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries,
> GFP_KERNEL);
> if (!vp_dev->msix_entries)
> @@ -311,6 +300,7 @@ static int vp_request_vectors(struct vir
> for (i = 0; i < nvectors; ++i)
> vp_dev->msix_entries[i].entry = i;
>
> + /* pci_enable_msix returns positive if we can't get this many. */
> err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, nvectors);
> if (err > 0)
> err = -ENOSPC;
> @@ -356,10 +346,10 @@ error:
> return err;
> }
>
> -static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
> - void (*callback)(struct virtqueue *vq),
> - const char *name,
> - u16 vector)
> +static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
> + void (*callback)(struct virtqueue *vq),
> + const char *name,
> + u16 vector)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> struct virtio_pci_vq_info *info;
> @@ -408,7 +398,7 @@ static struct virtqueue *vp_find_vq(stru
> vq->priv = info;
> info->vq = vq;
>
> - if (vector != VIRTIO_MSI_NO_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) {
> @@ -484,14 +474,36 @@ static int vp_try_to_find_vqs(struct vir
> struct virtqueue *vqs[],
> vq_callback_t *callbacks[],
> const char *names[],
> - int nvectors,
> + bool use_msix,
> bool per_vq_vectors)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> u16 vector;
> - int i, err, allocated_vectors;
> + int i, err, nvectors, allocated_vectors;
>
> - err = vp_request_vectors(vdev, nvectors, per_vq_vectors);
> + 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;
shorter as vp_dev->intx_enabled = !err
> + return err;
Is that all? Don't we need to create the vqs?
> + }
> +
> + 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 one for all vqs. */
> + nvectors = 2;
> + }
> +
> + err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors);
> if (err)
> goto error_request;
>
> @@ -504,15 +516,17 @@ static int vp_try_to_find_vqs(struct vir
> vector = allocated_vectors++;
> else
> vector = VP_MSIX_VQ_VECTOR;
> - vqs[i] = vp_find_vq(vdev, i, callbacks[i], names[i], vector);
> + vqs[i] = setup_vq(vdev, i, callbacks[i], names[i], vector);
> 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 && vector != VIRTIO_MSI_NO_VECTOR) {
> - snprintf(vp_dev->msix_names[vector], sizeof *vp_dev->msix_names,
> - "%s-%s", dev_name(&vp_dev->vdev.dev), names[i]);
> + snprintf(vp_dev->msix_names[vector],
> + sizeof *vp_dev->msix_names,
> + "%s-%s",
> + dev_name(&vp_dev->vdev.dev), names[i]);
> err = request_irq(vp_dev->msix_entries[vector].vector,
> vring_interrupt, 0,
> vp_dev->msix_names[vector], vqs[i]);
> @@ -537,28 +551,20 @@ static int vp_find_vqs(struct virtio_dev
> vq_callback_t *callbacks[],
> const char *names[])
> {
> - int vectors = 0;
> - int i, uninitialized_var(err);
> + int err;
>
> - /* How many vectors would we like? */
> - for (i = 0; i < nvqs; ++i)
> - if (callbacks[i])
> - ++vectors;
> -
> - /* We want at most one vector per queue and one for config changes. */
> - err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
> - vectors + 1, true);
> + /* Try MSI-X with one vector per queue. */
> + err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, true, true);
> if (!err)
> return 0;
> - /* Fallback to separate vectors for config and a shared for queues. */
> + /* Fallback: MSI-X with one vector for config, one shared for queues. */
> err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
> - 2, false);
> + true, false);
> if (!err)
> return 0;
> /* Finally fall back to regular interrupts. */
> - err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
> - 0, false);
> - return err;
> + return vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
> + false, false);
> }
>
> static struct virtio_config_ops virtio_pci_config_ops = {
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