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.
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()
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;
+ return err;
+ }
+
+ 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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