Re: [PATCH 5/7] vfio: Use new interfaces for MSI/MSI-X enablement

Alexander Gordeev
2014-01-08T07:40:21Z

On Tue, Jan 07, 2014 at 11:34:13AM -0700, Alex Williamson wrote:
> On Tue, 2014-01-07 at 19:05 +0100, Alexander Gordeev wrote:
> > This update also fixes a bug when deprecated pci_enable_msix()
> > and pci_enable_msi_block() functions return a positive return
> > value which indicats the number of interrupts that could have
> > been allocated rather than a successful allocation. The driver
> > misinterpreted this value and assumed MSI-X/MSIs are enabled,
> > although in fact it were not.
>
> No, the driver interpreted it correctly, which is why anything other
> than zero is handled as an error. This patch looks incorrect if the new
> interfaces follow the same return convention. Thanks,

The new interfaces differ wrt the return value - it is eigher a negative
error code or a positive number of successfuly allocated vectors.

If the user level makes use of a number of vectors that could have been
allocated then it should cease doing it, since only 0 or a negative error
code is returned after this update.

The changelog is incorrect as the driver indeed bailes out on positive
return values. I will send a updated version.

> Alex

--
Regards,
Alexander Gordeev
agordeev@redhat.com