Re: [PATCH mlx5-next v6 1/4] PCI: Add sysfs callback to allow MSI-X table size change of SR-IOV VFs

Leon Romanovsky
2021-02-24T09:54:55Z

On Tue, Feb 23, 2021 at 03:07:43PM -0600, Bjorn Helgaas wrote:
> On Sun, Feb 21, 2021 at 08:59:18AM +0200, Leon Romanovsky wrote:
> > On Sat, Feb 20, 2021 at 01:06:00PM -0600, Bjorn Helgaas wrote:
> > > On Fri, Feb 19, 2021 at 09:20:18AM +0100, Greg Kroah-Hartman wrote:
> > >
> > > > Ok, can you step back and try to explain what problem you are trying to
> > > > solve first, before getting bogged down in odd details? I find it
> > > > highly unlikely that this is something "unique", but I could be wrong as
> > > > I do not understand what you are wanting to do here at all.
> > >
> > > We want to add two new sysfs files:
> > >
> > > sriov_vf_total_msix, for PF devices
> > > sriov_vf_msix_count, for VF devices associated with the PF
> > >
> > > AFAICT it is *acceptable* if they are both present always. But it
> > > would be *ideal* if they were only present when a driver that
> > > implements the ->sriov_get_vf_total_msix() callback is bound to the
> > > PF.
> >
> > BTW, we already have all possible combinations: static, static with
> > folder, with and without "sriov_" prefix, dynamic with and without
> > folders on VFs.
> >
> > I need to know on which version I'll get Acked-by and that version I
> > will resubmit.
>
> I propose that you make static attributes for both files, so
> "sriov_vf_total_msix" is visible for *every* PF in the system and
> "sriov_vf_msix_count" is visible for *every* VF in the system.

No problem, this is close to v0/v1.

>
> The PF "sriov_vf_total_msix" show function can return zero if there's
> no PF driver or it doesn't support ->sriov_get_vf_total_msix().
> (Incidentally, I think the documentation should mention that when it
> *is* supported, the contents of this file are *constant*, i.e., it
> does not decrease as vectors are assigned to VFs.)
>
> The "sriov_vf_msix_count" set function can ignore writes if there's no
> PF driver or it doesn't support ->sriov_get_vf_total_msix(), or if a
> VF driver is bound.

Just to be clear, why don't we return EINVAL/EOPNOTSUPP instead of
silently ignore?

Thanks