Re: [PATCH] pci: make reset_subordinate hotplug safe

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Alex, Lukas]

On Wed, Jan 14, 2026 at 10:58:21AM -0800, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Use the slot reset method when resetting the bridge if the bus contains
> hotplug slots. This fixes spurious hotplug events the secondary bus
> reset triggers by utilizing slot's specific reset callback that ignores
> link events.

What do these spurious events look like in dmesg?

> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
> The new function introduced here is essentially the same as
> pci_bus_error_reset, except it uses the reset functions that save and
> restore the device. This is the same as before if not resetting a
> hotplug slot.
> 
>  drivers/pci/pci-sysfs.c |  3 +--
>  drivers/pci/pci.c       | 27 +++++++++++++++++++++++++++
>  drivers/pci/pci.h       |  2 +-
>  3 files changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 3881359440b1a..5c7c6f0c435f3 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -553,7 +553,6 @@ static ssize_t reset_subordinate_store(struct device *dev,
>  				const char *buf, size_t count)
>  {
>  	struct pci_dev *pdev = to_pci_dev(dev);
> -	struct pci_bus *bus = pdev->subordinate;
>  	unsigned long val;
>  
>  	if (!capable(CAP_SYS_ADMIN))
> @@ -563,7 +562,7 @@ static ssize_t reset_subordinate_store(struct device *dev,
>  		return -EINVAL;
>  
>  	if (val) {
> -		int ret = __pci_reset_bus(bus);
> +		int ret = pci_reset_bridge(pdev);
>  
>  		if (ret)
>  			return ret;
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b14dd064006cc..ca426ff68c820 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5747,6 +5747,33 @@ int __pci_reset_bus(struct pci_bus *bus)
>  	return rc;
>  }
>  
> +int pci_reset_bridge(struct pci_dev *bridge)
> +{
> +	struct pci_bus *bus = bridge->subordinate;
> +	struct pci_slot *slot;
> +
> +	if (!bus)
> +		return -ENOTTY;
> +
> +	mutex_lock(&pci_slot_mutex);
> +	if (list_empty(&bus->slots))
> +		goto bus_reset;
> +
> +	list_for_each_entry(slot, &bus->slots, list)
> +		if (pci_probe_reset_slot(slot))
> +			goto bus_reset;
> +
> +	list_for_each_entry(slot, &bus->slots, list)
> +		if (__pci_reset_slot(slot))
> +			goto bus_reset;
> +
> +	mutex_unlock(&pci_slot_mutex);
> +	return 0;
> +bus_reset:
> +	mutex_unlock(&pci_slot_mutex);
> +	return __pci_reset_bus(bus);
> +}
> +
>  /**
>   * pci_reset_bus - Try to reset a PCI bus
>   * @pdev: top level PCI device to reset via slot/bus
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 36f8c0985430a..f216e7a37d726 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -197,7 +197,7 @@ bool pci_reset_supported(struct pci_dev *dev);
>  void pci_init_reset_methods(struct pci_dev *dev);
>  int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
>  int pci_bus_error_reset(struct pci_dev *dev);
> -int __pci_reset_bus(struct pci_bus *bus);
> +int pci_reset_bridge(struct pci_dev *dev);
>  
>  struct pci_cap_saved_data {
>  	u16		cap_nr;
> -- 
> 2.47.3
>