On Tue, 15 Mar 2016 11:26:50 +0100 (CET)
Julia Lawall <julia.lawall@xxxxxxx> wrote:
> Hello,
>
> I was looking at the following code in the file
> drivers/vfio/pci/vfio_pci_intrs.c:
>
> ret = pci_enable_msix_range(pdev, vdev->msix, 1, nvec);
> if (ret < nvec) {
> if (ret > 0)
> pci_disable_msix(pdev);
> kfree(vdev->msix);
> kfree(vdev->ctx);
> return ret;
> }
>
> I was wondering what is the point of using a range of 1 .. nvec if there
> is going to be a failure if the number of allocated irqs is less than
> nvec?
Hi Julia,
The intention is that on failure we can indicate to the user a value
that might work. If we were to call with {nvec, nvec} we'd only get
back -ENOSPC and the user could only arbitrarily decrease the request
by some amount and try again. By using {1, nvec} we can hopefully
provide a useful next step. On the other hand, we haven't enabled the
number of vectors the user requested, so it doesn't seem to make sense
to leave any enabled. Thanks,
Alex
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