Re: [BUGFIX] PCI/PM: Fix proc config reg access for D3cold and bridge suspending

[Bjorn Helgaas]

On Wed, Oct 24, 2012 at 7:36 PM, Huang Ying <ying.huang@xxxxxxxxx> wrote:
> In
>
>   https://bugzilla.kernel.org/show_bug.cgi?id=48981
>
> Peter reported that /proc/bus/pci/??/??.? does not works for 3.6.
> This is This is because the device configuration space registers will
> be not accessible if the corresponding parent bridge is suspended or
> the device is put into D3cold state.
>
> This is the same as /sys/bus/pci/devices/0000:??:??.?/config access
> issue.  So the function used to solve sysfs issue is used to solve
> this issue.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Peter <lekensteyn@xxxxxxxxx>

Is this bug the same as the one originally reported by Forrest Loomis
(original reporter of bug 48981)?  And
https://bugzilla.kernel.org/show_bug.cgi?id=49031, reported by Micael
Dias (Rafael marked 49031 as a duplicate of 48981)?

If so, I'll mention Forrest and Micael and bug 49031 here as well.

> Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>
> ---
>  drivers/pci/pci-sysfs.c |   34 ----------------------------------
>  drivers/pci/pci.c       |   32 ++++++++++++++++++++++++++++++++
>  drivers/pci/pci.h       |    2 ++
>  drivers/pci/proc.c      |    8 ++++++++
>  4 files changed, 42 insertions(+), 34 deletions(-)
>
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -458,40 +458,6 @@ boot_vga_show(struct device *dev, struct
>  }
>  struct device_attribute vga_attr = __ATTR_RO(boot_vga);
>
> -static void
> -pci_config_pm_runtime_get(struct pci_dev *pdev)
> -{
> -       struct device *dev = &pdev->dev;
> -       struct device *parent = dev->parent;
> -
> -       if (parent)
> -               pm_runtime_get_sync(parent);
> -       pm_runtime_get_noresume(dev);
> -       /*
> -        * pdev->current_state is set to PCI_D3cold during suspending,
> -        * so wait until suspending completes
> -        */
> -       pm_runtime_barrier(dev);
> -       /*
> -        * Only need to resume devices in D3cold, because config
> -        * registers are still accessible for devices suspended but
> -        * not in D3cold.
> -        */
> -       if (pdev->current_state == PCI_D3cold)
> -               pm_runtime_resume(dev);
> -}
> -
> -static void
> -pci_config_pm_runtime_put(struct pci_dev *pdev)
> -{
> -       struct device *dev = &pdev->dev;
> -       struct device *parent = dev->parent;
> -
> -       pm_runtime_put(dev);
> -       if (parent)
> -               pm_runtime_put_sync(parent);
> -}
> -
>  static ssize_t
>  pci_read_config(struct file *filp, struct kobject *kobj,
>                 struct bin_attribute *bin_attr,
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1858,6 +1858,38 @@ bool pci_dev_run_wake(struct pci_dev *de
>  }
>  EXPORT_SYMBOL_GPL(pci_dev_run_wake);
>
> +void pci_config_pm_runtime_get(struct pci_dev *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct device *parent = dev->parent;
> +
> +       if (parent)
> +               pm_runtime_get_sync(parent);
> +       pm_runtime_get_noresume(dev);
> +       /*
> +        * pdev->current_state is set to PCI_D3cold during suspending,
> +        * so wait until suspending completes
> +        */
> +       pm_runtime_barrier(dev);
> +       /*
> +        * Only need to resume devices in D3cold, because config
> +        * registers are still accessible for devices suspended but
> +        * not in D3cold.
> +        */
> +       if (pdev->current_state == PCI_D3cold)
> +               pm_runtime_resume(dev);
> +}
> +
> +void pci_config_pm_runtime_put(struct pci_dev *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct device *parent = dev->parent;
> +
> +       pm_runtime_put(dev);
> +       if (parent)
> +               pm_runtime_put_sync(parent);
> +}
> +
>  /**
>   * pci_pm_init - Initialize PM functions of given PCI device
>   * @dev: PCI device to handle.
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -72,6 +72,8 @@ extern void pci_disable_enabled_device(s
>  extern int pci_finish_runtime_suspend(struct pci_dev *dev);
>  extern int __pci_pme_wakeup(struct pci_dev *dev, void *ign);
>  extern void pci_wakeup_bus(struct pci_bus *bus);
> +extern void pci_config_pm_runtime_get(struct pci_dev *dev);
> +extern void pci_config_pm_runtime_put(struct pci_dev *dev);
>  extern void pci_pm_init(struct pci_dev *dev);
>  extern void platform_pci_wakeup_init(struct pci_dev *dev);
>  extern void pci_allocate_cap_save_buffers(struct pci_dev *dev);
> --- a/drivers/pci/proc.c
> +++ b/drivers/pci/proc.c
> @@ -76,6 +76,8 @@ proc_bus_pci_read(struct file *file, cha
>         if (!access_ok(VERIFY_WRITE, buf, cnt))
>                 return -EINVAL;
>
> +       pci_config_pm_runtime_get(dev);
> +
>         if ((pos & 1) && cnt) {
>                 unsigned char val;
>                 pci_user_read_config_byte(dev, pos, &val);
> @@ -121,6 +123,8 @@ proc_bus_pci_read(struct file *file, cha
>                 cnt--;
>         }
>
> +       pci_config_pm_runtime_put(dev);
> +
>         *ppos = pos;
>         return nbytes;
>  }
> @@ -146,6 +150,8 @@ proc_bus_pci_write(struct file *file, co
>         if (!access_ok(VERIFY_READ, buf, cnt))
>                 return -EINVAL;
>
> +       pci_config_pm_runtime_get(dev);
> +
>         if ((pos & 1) && cnt) {
>                 unsigned char val;
>                 __get_user(val, buf);
> @@ -191,6 +197,8 @@ proc_bus_pci_write(struct file *file, co
>                 cnt--;
>         }
>
> +       pci_config_pm_runtime_put(dev);
> +
>         *ppos = pos;
>         i_size_write(ino, dp->size);
>         return nbytes;
> --
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