Re: [PATCH] ntb: Use pci_enable_msix_range() instead of pci_enable_msix()

From: Alexander Gordeev
Date: Wed Feb 19 2014 - 14:21:07 EST


On Wed, Feb 19, 2014 at 11:09:27AM -0700, Jon Mason wrote:
> > diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c
> > index 170e8e6..fda37eb 100644
> > --- a/drivers/ntb/ntb_hw.c
> > +++ b/drivers/ntb/ntb_hw.c
> > @@ -1085,21 +1085,15 @@ static int ntb_setup_msix(struct ntb_device *ndev)
> > struct msix_entry *msix;
> > int msix_entries;
> > int rc, i;
> > - u16 val;
> >
> > - if (!pdev->msix_cap) {
> > - rc = -EIO;
> > - goto err;
> > - }
> > -
> > - rc = pci_read_config_word(pdev, pdev->msix_cap + PCI_MSIX_FLAGS, &val);
> > - if (rc)
> > + rc = pci_msix_vec_count(pdev);
>
> Nit, you should probably use msix_entries instead of rc in this case.

This way it resembles the code few lines below, so the style looks more
consistent. Whichever you wish, though ;)

> > + if (rc < 0) {
> > goto err;
> > -
> > - msix_entries = msix_table_size(val);
> > - if (msix_entries > ndev->limits.msix_cnt) {
> > + } else if (rc > ndev->limits.msix_cnt) {
> > rc = -EINVAL;
> > goto err;
> > + } else {
> > + msix_entries = rc;
> > }
>
> Style Nit. Braces with only one line. If you make the change above,
> then it is moot.

Not on the top of my head, but do we mix bracing this way?

> >
> > ndev->msix_entries = kmalloc(sizeof(struct msix_entry) * msix_entries,
> > @@ -1112,26 +1106,21 @@ static int ntb_setup_msix(struct ntb_device *ndev)
> > for (i = 0; i < msix_entries; i++)
> > ndev->msix_entries[i].entry = i;
> >
> > - rc = pci_enable_msix(pdev, ndev->msix_entries, msix_entries);
> > - if (rc < 0)
> > - goto err1;
> > - if (rc > 0) {
> > + if (ndev->hw_type != BWD_HW)
> > /* On SNB, the link interrupt is always tied to 4th vector. If
> > * we can't get all 4, then we can't use MSI-X.
> > */
> > - if (ndev->hw_type != BWD_HW) {
> > - rc = -EIO;
> > - goto err1;
> > - }
> > -
> > - dev_warn(&pdev->dev,
> > - "Only %d MSI-X vectors. Limiting the number of queues to that number.\n",
> > - rc);
> > + rc = pci_enable_msix_range(pdev, ndev->msix_entries,
> > + msix_entries, msix_entries);
> > + else
> > + rc = pci_enable_msix_range(pdev, ndev->msix_entries,
> > + 1, msix_entries);
>
> Actually, this must be 2 for the min. One for the Data and one for
> the Link. If you look a few lines after this in the original code,
> there is a grabbing of the last vector for the link. I realize there
> is currently no check for this in the driver and a potential error
> case occurs. I can make a separate patch to correct this issue if
> this patch is not going through my tree.

Well, I can re-post with a separate fix with this condition updated...

} else if (rc < 2 || rc > ndev->limits.msix_cnt) {
rc = -EINVAL;
goto err;
}

...and the original patch with call to pci_enable_msix_range( ...,
2, ndev->limits.msix_cnt)

Will it work with both BWD_HW and non-BWD_HW hardware?

> Thanks,
> Jon
>
>
> > + if (rc < 0)
> > + goto err1;
> > + else if (rc < msix_entries) {
> > + dev_warn(&pdev->dev, "Only %d MSI-X vectors. "
> > + "Limiting the number of queues to that number.\n", rc);
> > msix_entries = rc;
> > -
> > - rc = pci_enable_msix(pdev, ndev->msix_entries, msix_entries);
> > - if (rc)
> > - goto err1;
> > }
> >
> > for (i = 0; i < msix_entries; i++) {
> > diff --git a/drivers/ntb/ntb_hw.h b/drivers/ntb/ntb_hw.h
> > index bbdb7ed..d307107 100644
> > --- a/drivers/ntb/ntb_hw.h
> > +++ b/drivers/ntb/ntb_hw.h
> > @@ -60,8 +60,6 @@
> > #define PCI_DEVICE_ID_INTEL_NTB_SS_HSX 0x2F0F
> > #define PCI_DEVICE_ID_INTEL_NTB_B2B_BWD 0x0C4E
> >
> > -#define msix_table_size(control) ((control & PCI_MSIX_FLAGS_QSIZE)+1)
> > -
> > #ifndef readq
> > static inline u64 readq(void __iomem *addr)
> > {
> > --
> > 1.7.7.6
> >

--
Regards,
Alexander Gordeev
agordeev@xxxxxxxxxx
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