Re: [RFC PATCH 00/13] Remove implicit devres from pci_intx()

[Philipp Stanner <pstanner@xxxxxxxxxx>]

On Wed, 2024-10-09 at 20:32 +0200, Heiner Kallweit wrote:
> On 09.10.2024 10:35, Philipp Stanner wrote:
> > Hi all,
> > 
> > this series removes a problematic feature from pci_intx(). That
> > function
> > sometimes implicitly uses devres for automatic cleanup. We should
> > get
> > rid of this implicit behavior.
> > 
> > To do so, a pci_intx() version that is always-managed, and one that
> > is
> > never-managed are provided. Then, all pci_intx() users are ported
> > to the
> > version they need. Afterwards, pci_intx() can be cleaned up and the
> > users of the never-managed version be ported back to pci_intx().
> > 
> > This way we'd get this PCI API consistent again.
> > 
> AFAICS pci_intx() is used only by drivers which haven't been
> converted
> to the pci_alloc_irq_vectors() API yet. Wouldn't it be better to do
> this
> instead of trying to improve pci_intx()?

This would be the créme-de-la-créme-solution, yes.

But such a portation would require more detailed knowledge of the old
drivers.

In this discussion, Alex points out that at least in some drivers, you
can't replace pci_intx() without further ado:
https://lore.kernel.org/all/20240904151020.486f599e.alex.williamson@xxxxxxxxxx/


What we could do is mark pci_intx() and pcim_intx() as deprecated and
point everyone to pci_alloc_irq_vectors(). Then someone can look into
porting the old drivers at some point in the future.


P.


> Eventually pci_intx() would have to be used in PCI core only.
> 
> > The last patch obviously reverts the previous patches that made
> > drivers
> > use pci_intx_unmanaged(). But this way it's easier to review and
> > approve. It also makes sure that each checked out commit should
> > provide
> > correct behavior, not just the entire series as a whole.
> > 
> > Merge plan for this would be to enter through the PCI tree.
> > 
> > Please say so if you've got concerns with the general idea behind
> > the
> > RFC.
> > 
> > Regards,
> > P.
> > 
> > Philipp Stanner (13):
> >   PCI: Prepare removing devres from pci_intx()
> >   ALSA: hda: hda_intel: Use always-managed version of pcim_intx()
> >   drivers/xen: Use never-managed version of pci_intx()
> >   net/ethernet: Use never-managed version of pci_intx()
> >   net/ntb: Use never-managed version of pci_intx()
> >   misc: Use never-managed version of pci_intx()
> >   vfio/pci: Use never-managed version of pci_intx()
> >   PCI: MSI: Use never-managed version of pci_intx()
> >   ata: Use always-managed version of pci_intx()
> >   staging: rts5280: Use always-managed version of pci_intx()
> >   wifi: qtnfmac: use always-managed version of pcim_intx()
> >   HID: amd_sfh: Use always-managed version of pcim_intx()
> >   Remove devres from pci_intx()
> > 
> >  drivers/ata/ahci.c                            |  2 +-
> >  drivers/ata/ata_piix.c                        |  2 +-
> >  drivers/ata/pata_rdc.c                        |  2 +-
> >  drivers/ata/sata_sil24.c                      |  2 +-
> >  drivers/ata/sata_sis.c                        |  2 +-
> >  drivers/ata/sata_uli.c                        |  2 +-
> >  drivers/ata/sata_vsc.c                        |  2 +-
> >  drivers/hid/amd-sfh-hid/amd_sfh_pcie.c        |  4 ++--
> >  drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_init.c |  2 +-
> >  .../wireless/quantenna/qtnfmac/pcie/pcie.c    |  2 +-
> >  drivers/pci/devres.c                          | 24 +++------------
> > ----
> >  drivers/pci/pci.c                             | 14 +----------
> >  drivers/staging/rts5208/rtsx.c                |  2 +-
> >  include/linux/pci.h                           |  1 +
> >  sound/pci/hda/hda_intel.c                     |  2 +-
> >  15 files changed, 18 insertions(+), 47 deletions(-)
> > 
>