Re: [PATCH v7 07/13] PCI: Move dev-enabled status bit to struct pci_dev

[Philipp Stanner <pstanner@redhat.com>]

On Wed, 2024-06-05 at 16:11 -0500, Bjorn Helgaas wrote:
> On Wed, Jun 05, 2024 at 10:15:59AM +0200, Philipp Stanner wrote:
> > The bit describing whether the PCI device is currently enabled is
> > stored
> > in struct pci_devres. Besides this struct being subject of a
> > cleanup
> > process, struct pci_device is in general the right place to store
> > this
> > information, since it is not devres-specific.
> > 
> > Move the 'enabled' boolean bit to struct pci_dev.
> 
> I think this (and the similar 'pinned' patch) appeared in v6.

Yes. This patch and its brothers serve to remove members from
struct pci_devres step by step, so it can ultimately be removed, so
that we won't have a generic devres struct anymore, but actual
resource-specific structs.

> 
> It sounds plausible to have this in struct pci_dev, but it's
> confusing
> to have both:
> 
>   pci_dev.enabled
>   pci_dev.enable_cnt, used by pci_is_enabled()
> 
> I haven't looked hard enough to see whether both are required.  If
> they are, I think we should rename "enabled" to something descriptive
> enough to make it obviously different from "enable_cnt".

I took a look at it and I think we can actually drop "enabled" and use
"enable_cnt" for everything. That would even simplify things more, I'd
say.

Let me provide that in v8.


P.

> 
> > Signed-off-by: Philipp Stanner <pstanner@redhat.com>
> > ---
> >  drivers/pci/devres.c | 11 ++++-------
> >  drivers/pci/pci.c    | 17 ++++++++++-------
> >  drivers/pci/pci.h    |  1 -
> >  include/linux/pci.h  |  1 +
> >  4 files changed, 15 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
> > index 572a4e193879..ea590caf8995 100644
> > --- a/drivers/pci/devres.c
> > +++ b/drivers/pci/devres.c
> > @@ -398,7 +398,7 @@ static void pcim_release(struct device *gendev,
> > void *res)
> >         if (this->restore_intx)
> >                 pci_intx(dev, this->orig_intx);
> >  
> > -       if (this->enabled && !this->pinned)
> > +       if (!this->pinned)
> >                 pci_disable_device(dev);
> >  }
> >  
> > @@ -441,14 +441,11 @@ int pcim_enable_device(struct pci_dev *pdev)
> >         dr = get_pci_dr(pdev);
> >         if (unlikely(!dr))
> >                 return -ENOMEM;
> > -       if (dr->enabled)
> > -               return 0;
> >  
> >         rc = pci_enable_device(pdev);
> > -       if (!rc) {
> > +       if (!rc)
> >                 pdev->is_managed = 1;
> > -               dr->enabled = 1;
> > -       }
> > +
> >         return rc;
> >  }
> >  EXPORT_SYMBOL(pcim_enable_device);
> > @@ -466,7 +463,7 @@ void pcim_pin_device(struct pci_dev *pdev)
> >         struct pci_devres *dr;
> >  
> >         dr = find_pci_dr(pdev);
> > -       WARN_ON(!dr || !dr->enabled);
> > +       WARN_ON(!dr || !pdev->enabled);
> >         if (dr)
> >                 dr->pinned = 1;
> >  }
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 8dd711b9a291..04accdfab7ce 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -2011,6 +2011,9 @@ static int do_pci_enable_device(struct
> > pci_dev *dev, int bars)
> >         u16 cmd;
> >         u8 pin;
> >  
> > +       if (dev->enabled)
> > +               return 0;
> > +
> >         err = pci_set_power_state(dev, PCI_D0);
> >         if (err < 0 && err != -EIO)
> >                 return err;
> > @@ -2025,7 +2028,7 @@ static int do_pci_enable_device(struct
> > pci_dev *dev, int bars)
> >         pci_fixup_device(pci_fixup_enable, dev);
> >  
> >         if (dev->msi_enabled || dev->msix_enabled)
> > -               return 0;
> > +               goto success_out;
> >  
> >         pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
> >         if (pin) {
> > @@ -2035,6 +2038,8 @@ static int do_pci_enable_device(struct
> > pci_dev *dev, int bars)
> >                                               cmd &
> > ~PCI_COMMAND_INTX_DISABLE);
> >         }
> >  
> > +success_out:
> > +       dev->enabled = true;
> >         return 0;
> >  }
> >  
> > @@ -2193,6 +2198,9 @@ static void do_pci_disable_device(struct
> > pci_dev *dev)
> >  {
> >         u16 pci_command;
> >  
> > +       if (!dev->enabled)
> > +               return;
> > +
> >         pci_read_config_word(dev, PCI_COMMAND, &pci_command);
> >         if (pci_command & PCI_COMMAND_MASTER) {
> >                 pci_command &= ~PCI_COMMAND_MASTER;
> > @@ -2200,6 +2208,7 @@ static void do_pci_disable_device(struct
> > pci_dev *dev)
> >         }
> >  
> >         pcibios_disable_device(dev);
> > +       dev->enabled = false;
> >  }
> >  
> >  /**
> > @@ -2227,12 +2236,6 @@ void pci_disable_enabled_device(struct
> > pci_dev *dev)
> >   */
> >  void pci_disable_device(struct pci_dev *dev)
> >  {
> > -       struct pci_devres *dr;
> > -
> > -       dr = find_pci_dr(dev);
> > -       if (dr)
> > -               dr->enabled = 0;
> > -
> >         dev_WARN_ONCE(&dev->dev, atomic_read(&dev->enable_cnt) <=
> > 0,
> >                       "disabling already-disabled device");
> >  
> > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > index 9fd50bc99e6b..e223e0f7dada 100644
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -823,7 +823,6 @@ static inline pci_power_t
> > mid_pci_get_power_state(struct pci_dev *pdev)
> >   * then remove them from here.
> >   */
> >  struct pci_devres {
> > -       unsigned int enabled:1;
> >         unsigned int pinned:1;
> >         unsigned int orig_intx:1;
> >         unsigned int restore_intx:1;
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 16493426a04f..110548f00b3b 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -367,6 +367,7 @@ struct pci_dev {
> >                                            this is D0-D3, D0 being
> > fully
> >                                            functional, and D3 being
> > off. */
> >         u8              pm_cap;         /* PM capability offset */
> > +       unsigned int    enabled:1;      /* Whether this dev is
> > enabled */
> >         unsigned int    imm_ready:1;    /* Supports Immediate
> > Readiness */
> >         unsigned int    pme_support:5;  /* Bitmask of states from
> > which PME#
> >                                            can be generated */
> > -- 
> > 2.45.0
> > 
>