[PATCHv4 2/2] virtio: refactor find_vqs
Rusty Russell
rusty at rustcorp.com.au
Sun Aug 9 16:37:52 PDT 2009
On Tue, 28 Jul 2009 06:03:08 pm Michael S. Tsirkin wrote:
> 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.
Yes, but unfortunately request_vectors was never really symmetrical :(
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.
> > - 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?
Oh, yeah :)
This patch applies on top. Basically reverts that part, and
renames vector to msix_vector, which I think makes the code more
readable.
virtio: more PCI minor cleanups
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
---
drivers/virtio/virtio_pci.c | 73 +++++++++++++++++++++-----------------------
1 file changed, 36 insertions(+), 37 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
@@ -84,7 +84,7 @@ struct virtio_pci_vq_info
struct list_head node;
/* MSI-X vector (or none) */
- unsigned vector;
+ unsigned msix_vector;
};
/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
@@ -349,7 +349,7 @@ error:
static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
void (*callback)(struct virtqueue *vq),
const char *name,
- u16 vector)
+ u16 msix_vector)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
struct virtio_pci_vq_info *info;
@@ -374,7 +374,7 @@ static struct virtqueue *setup_vq(struct
info->queue_index = index;
info->num = num;
- info->vector = vector;
+ info->msix_vector = msix_vector;
size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
@@ -398,10 +398,10 @@ static struct virtqueue *setup_vq(struct
vq->priv = info;
info->vq = vq;
- 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);
+ if (msix_vector == VIRTIO_MSI_NO_VECTOR) {
err = -EBUSY;
goto out_assign;
}
@@ -462,7 +462,8 @@ static void vp_del_vqs(struct virtio_dev
list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
info = vq->priv;
if (vp_dev->per_vq_vectors)
- free_irq(vp_dev->msix_entries[info->vector].vector, vq);
+ free_irq(vp_dev->msix_entries[info->msix_vector].vector,
+ vq);
vp_del_vq(vq);
}
vp_dev->per_vq_vectors = false;
@@ -478,58 +479,56 @@ static int vp_try_to_find_vqs(struct vir
bool per_vq_vectors)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
- u16 vector;
+ u16 msix_vector;
int i, err, nvectors, allocated_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;
- return err;
+ if (err)
+ return err;
+ } 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;
+ }
+
+ err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors);
+ if (err)
+ goto error_request;
}
- 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;
-
vp_dev->per_vq_vectors = per_vq_vectors;
allocated_vectors = vp_dev->msix_used_vectors;
for (i = 0; i < nvqs; ++i) {
if (!callbacks[i] || !vp_dev->msix_enabled)
- vector = VIRTIO_MSI_NO_VECTOR;
+ msix_vector = VIRTIO_MSI_NO_VECTOR;
else if (vp_dev->per_vq_vectors)
- vector = allocated_vectors++;
+ msix_vector = allocated_vectors++;
else
- vector = VP_MSIX_VQ_VECTOR;
- vqs[i] = setup_vq(vdev, i, callbacks[i], names[i], vector);
+ msix_vector = VP_MSIX_VQ_VECTOR;
+ vqs[i] = setup_vq(vdev, i, callbacks[i], names[i], msix_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],
+ if (vp_dev->per_vq_vectors) {
+ snprintf(vp_dev->msix_names[msix_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]);
+ err = request_irq(msix_vector, vring_interrupt, 0,
+ vp_dev->msix_names[msix_vector],
+ vqs[i]);
if (err) {
vp_del_vq(vqs[i]);
goto error_find;
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