Re: [PATCH] Octeontx2-af: Fix pci_alloc_irq_vectors() return value check

[Simon Horman <horms@kernel.org>]

On Tue, Oct 14, 2025 at 03:50:47PM +0530, Harshit Mogalapalli wrote:
> Hi,
> 
> On 14/10/25 15:44, Harshit Mogalapalli wrote:
> > In cgx_probe() when pci_alloc_irq_vectors() fails the error value will
> > be negative and that check is sufficient.
> > 
> > 	err = pci_alloc_irq_vectors(pdev, nvec, nvec, PCI_IRQ_MSIX);
> >          if (err < 0 || err != nvec) {
> >          	...
> > 	}
> > 
> > Remove the check which compares err with nvec.
> > 
> > Fixes: 1463f382f58d ("octeontx2-af: Add support for CGX link management")
> > Suggested-by: Paolo Abeni <pabeni@redhat.com>
> > Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
> > ---
> > Only compile tested.
> > ---
> >   drivers/net/ethernet/marvell/octeontx2/af/cgx.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/marvell/octeontx2/af/cgx.c b/drivers/net/ethernet/marvell/octeontx2/af/cgx.c
> > index d374a4454836..f4d5a3c05fa4 100644
> > --- a/drivers/net/ethernet/marvell/octeontx2/af/cgx.c
> > +++ b/drivers/net/ethernet/marvell/octeontx2/af/cgx.c
> > @@ -1993,7 +1993,7 @@ static int cgx_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> >   	nvec = pci_msix_vec_count(cgx->pdev);
> >   	err = pci_alloc_irq_vectors(pdev, nvec, nvec, PCI_IRQ_MSIX);
> > -	if (err < 0 || err != nvec) {
> > +	if (err < 0) {
> >   		dev_err(dev, "Request for %d msix vectors failed, err %d\n",
> >   			nvec, err);
> 
> 
> Now that I think about it more, maybe we want to error out when err != nvec
> as well ? In that case maybe the right thing to do is leave the check as is
> and set err = -EXYZ before goto ?
> 
> Thanks,
> Harshit>   		goto err_release_regions;

Hi Harshit,

My reading of the documentation of pci_alloc_irq_vectors() is that
Because nvec is passed as both the min and max desired vectors,
either nvecs will be allocated, or -ENOSPC will be returned.

Maybe it is worth adding a comment about that to patch description
or the code. But I think the code in this patch is correct.