Re: [PATCH 7/9] ethernet: stmicro: Simplify PCI devres usage

Philipp Stanner
2024-08-20T07:52:47Z

On Mon, 2024-08-19 at 21:28 +0300, Andy Shevchenko wrote:
> On Mon, Aug 19, 2024 at 06:51:47PM +0200, Philipp Stanner wrote:
> > stmicro uses PCI devres in the wrong way. Resources requested
> > through pcim_* functions don't need to be cleaned up manually in
> > the
> > remove() callback or in the error unwind path of a probe()
> > function.
> >
> > Moreover, there is an unnecessary loop which only requests and
> > ioremaps
> > BAR 0, but iterates over all BARs nevertheless.
> >
> > Furthermore, pcim_iomap_regions() and pcim_iomap_table() have been
> > deprecated by the PCI subsystem in commit e354bb84a4c1 ("PCI:
> > Deprecate
> > pcim_iomap_table(), pcim_iomap_regions_request_all()").
> >
> > Replace these functions with pcim_iomap_region().
> >
> > Remove the unnecessary manual pcim_* cleanup calls.
> >
> > Remove the unnecessary loop over all BARs.
>
> ...
>
> loongson_dwmac_probe()
>
> > + memset(&res, 0, sizeof(res));
> > + res.addr = pcim_iomap_region(pdev, 0, pci_name(pdev));
> > + if (IS_ERR(res.addr)) {
> > + ret = PTR_ERR(res.addr);
> > + goto err_disable_device;
>
> It seems your series reveals issues in the error paths of .probe():s
> in many drivers...
>
> If we use pcim variant to enable device, why do we need to explicitly
> disable it?

No.

>
> >   }
>
> ...
>
> loongson_dwmac_remove()
>
> >   pci_disable_msi(pdev);
> >   pci_disable_device(pdev);
>
> Not sure why we need these either...

It's complicated.

The code uses pciM_enable_device(), but here in remove
pci_disable_device().

pcim_enable_device() sets up a disable callback which only calls
pci_disable_device() if pcim_pin_device() has not been called.

This code doesn't seem to call pcim_pin_device(), so I think
pci_disable_device() could be removed.

I definitely would not feel confident touching pci_disable_msi(),
though. The AFAIK biggest problem remaining in PCI devres is that the
MSI code base implicitly calls into devres, see here [1]

P.

[1] https://lore.kernel.org/all/ee44ea7ac760e73edad3f20b30b4d2fff66c1a85.camel@redhat.com/