On Thu, Aug 8, 2013 at 2:09 PM, Alex Williamson
<alex.williamson@xxxxxxxxxx> wrote:
> If the hotplug controller provides a way to reset a slot, use that
> before a direct parent bus reset. Like the bus reset option, this is
> only available when a single pci_dev occupies the slot.
>
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> ---
> drivers/pci/pci.c | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index d468608..9407aab 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -22,6 +22,7 @@
> #include <linux/interrupt.h>
> #include <linux/device.h>
> #include <linux/pm_runtime.h>
> +#include <linux/pci_hotplug.h>
> #include <asm-generic/pci-bridge.h>
> #include <asm/setup.h>
> #include "pci.h"
> @@ -3256,6 +3257,35 @@ static int pci_parent_bus_reset(struct pci_dev *dev, int probe)
> return 0;
> }
>
> +static int pci_reset_hotplug_slot(struct hotplug_slot *hotplug, int probe)
> +{
> + int rc = -ENOTTY;
> +
> + if (!hotplug || !try_module_get(hotplug->ops->owner))
> + return rc;
> +
> + if (hotplug->ops->reset_slot)
> + rc = hotplug->ops->reset_slot(hotplug, probe);
> +
> + module_put(hotplug->ops->owner);
> +
> + return rc;
> +}
> +
> +static int pci_dev_reset_slot_function(struct pci_dev *dev, int probe)
> +{
> + struct pci_dev *pdev;
> +
> + if (dev->subordinate || !dev->slot)
> + return -ENOTTY;
> +
> + list_for_each_entry(pdev, &dev->bus->devices, bus_list)
> + if (pdev != dev && pdev->slot == dev->slot)
> + return -ENOTTY;
> +
> + return pci_reset_hotplug_slot(dev->slot->hotplug, probe);
I don't think this is hotplug-safe. It looks like pci_bus_sem might
be the right semaphore to hold while verifying that we won't reset any
unintended devices. But I think most users of the bus->devices list
are unprotected, so there's no point in trying to fix just this one.
> +}
> +
> static int __pci_dev_reset(struct pci_dev *dev, int probe)
> {
> int rc;
> @@ -3278,6 +3308,10 @@ static int __pci_dev_reset(struct pci_dev *dev, int probe)
> if (rc != -ENOTTY)
> goto done;
>
> + rc = pci_dev_reset_slot_function(dev, probe);
> + if (rc != -ENOTTY)
> + goto done;
> +
> rc = pci_parent_bus_reset(dev, probe);
> done:
> return rc;
>
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