Re: [PATCH v3] vdpa: solidrun: Replace deprecated PCI functions

[Stefano Garzarella]

On Fri, Dec 13, 2024 at 07:39:46PM +0100, Philipp Stanner wrote:
> On Fri, 2024-12-13 at 16:10 +0100, Stefano Garzarella wrote:
> > On Wed, Dec 11, 2024 at 11:47:05AM +0100, Philipp Stanner wrote:
> > > The PCI functions
> > >
> > > 	pcim_iomap_regions()
> > > 	pcim_iounmap_regions()
> > > 	pcim_iomap_table()
> > >
> > > have been deprecated by the PCI subsystem.
> > >
> > > Replace these functions with their successors pcim_iomap_region()
> > > and
> > > pcim_iounmap_region().
> > >
> > > Signed-off-by: Philipp Stanner <pstanner@xxxxxxxxxx>
> > > ---
> > > Changes in v3:
> > >  - Move __iomem *io declaration into the loop. (Stefano)
> > >
> > > Changes in v2:
> > >  - Fix build warning because of dead variable.
> > >  - Make "bars_found" a boolean, since only true or false are
> > > relevant.
> > > ---
> > > drivers/vdpa/solidrun/snet_main.c | 56 ++++++++++++++--------------
> > > ---
> > > 1 file changed, 26 insertions(+), 30 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/solidrun/snet_main.c
> > > b/drivers/vdpa/solidrun/snet_main.c
> > > index c8b74980dbd1..643e335f00f1 100644
> > > --- a/drivers/vdpa/solidrun/snet_main.c
> > > +++ b/drivers/vdpa/solidrun/snet_main.c
> > > @@ -556,59 +556,58 @@ static const struct vdpa_config_ops
> > > snet_config_ops = {
> > > static int psnet_open_pf_bar(struct pci_dev *pdev, struct psnet
> > > *psnet)
> > > {
> > > 	char *name;
> > > -	int ret, i, mask = 0;
> > > +	unsigned short i;
> > > +	bool bars_found = false;
> > > +
> > > +	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "psnet[%s]-
> > > bars", pci_name(pdev));
> > > +	if (!name)
> > > +		return -ENOMEM;
> > > +
> > > 	/* We don't know which BAR will be used to communicate..
> > > 	 * We will map every bar with len > 0.
> > > 	 *
> > > 	 * Later, we will discover the BAR and unmap all other
> > > BARs.
> > > 	 */
> > > 	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> > > -		if (pci_resource_len(pdev, i))
> > > -			mask |= (1 << i);
> > > +		void __iomem *io;
> > > +
> > > +		if (pci_resource_len(pdev, i) == 0)
> > > +			continue;
> > > +
> > > +		io = pcim_iomap_region(pdev, i, name);
> > > +		if (IS_ERR(io)) {
> > > +			SNET_ERR(pdev, "Failed to request and map
> > > PCI BARs\n");
> > > +			return PTR_ERR(io);
> > > +		}
> > > +
> > > +		psnet->bars[i] = io;
> > > +		bars_found = true;
> > > 	}
> > >
> > > 	/* No BAR can be used.. */
> > > -	if (!mask) {
> > > +	if (!bars_found) {
> > > 		SNET_ERR(pdev, "Failed to find a PCI BAR\n");
> > > 		return -ENODEV;
> > > 	}
> > >
> > > -	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "psnet[%s]-
> > > bars", pci_name(pdev));
> > > -	if (!name)
> > > -		return -ENOMEM;
> > > -
> > > -	ret = pcim_iomap_regions(pdev, mask, name);
> > > -	if (ret) {
> > > -		SNET_ERR(pdev, "Failed to request and map PCI
> > > BARs\n");
> > > -		return ret;
> > > -	}
> > > -
> > > -	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> > > -		if (mask & (1 << i))
> > > -			psnet->bars[i] =
> > > pcim_iomap_table(pdev)[i];
> > > -	}
> > > -
> > > 	return 0;
> > > }
> > >
> > > static int snet_open_vf_bar(struct pci_dev *pdev, struct snet
> > > *snet)
> > > {
> > > 	char *name;
> > > -	int ret;
> > >
> > > 	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "snet[%s]-
> > > bars", pci_name(pdev));
> > > 	if (!name)
> > > 		return -ENOMEM;
> > >
> > > 	/* Request and map BAR */
> > > -	ret = pcim_iomap_regions(pdev, BIT(snet->psnet-
> > > >cfg.vf_bar), name);
> > > -	if (ret) {
> > > +	snet->bar = pcim_iomap_region(pdev, snet->psnet-
> > > >cfg.vf_bar, name);
> >
> > Could we also use a temporary variable here as we did in
> > psnet_open_pf_bar()?
>
> We can. Some maintainers want it so, others so
>
> > It seems to me that no one uses `!snet->bar` for now to check whether
> > they are configured or not, but maybe better to prevent, WDYT?
>
> So it seems that this driver is a bit special as its probe() function
> can take different paths running into one of the respective request
> functions.
> Doesn't look to me as if pcim_iomap_region() could fail and the driver
> would still load?

yeah, it's not super clear to me how physical and virtual functions are
managed.

> Anyways, better safe than sorry. If you think it's safer I can modify
> it so those pointers are valid or NULL.

Just because this way we leave the behavior the same as before this 
change, but I don't have a strong opinion, actually it's the error path 
of the probe, so maybe the device is completely deallocated.

Thanks,
Stefano

> P.
>
> > Thanks,
> > Stefano
> >
> > > +	if (IS_ERR(snet->bar)) {
> > > 		SNET_ERR(pdev, "Failed to request and map PCI BAR
> > > for a VF\n");
> > > -		return ret;
> > > +		return PTR_ERR(snet->bar);
> > > 	}
> > >
> > > -	snet->bar = pcim_iomap_table(pdev)[snet->psnet-
> > > >cfg.vf_bar];
> > > -
> > > 	return 0;
> > > }
> > >
> > > @@ -656,15 +655,12 @@ static int psnet_detect_bar(struct psnet
> > > *psnet, u32 off)
> > >
> > > static void psnet_unmap_unused_bars(struct pci_dev *pdev, struct
> > > psnet *psnet)
> > > {
> > > -	int i, mask = 0;
> > > +	unsigned short i;
> > >
> > > 	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> > > 		if (psnet->bars[i] && i != psnet->barno)
> > > -			mask |= (1 << i);
> > > +			pcim_iounmap_region(pdev, i);
> > > 	}
> > > -
> > > -	if (mask)
> > > -		pcim_iounmap_regions(pdev, mask);
> > > }
> > >
> > > /* Read SNET config from PCI BAR */
> > > --
> > > 2.47.1
> > >