Re: [PATCH] PCI/AER: Block runtime suspend when handling errors

[Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 2/9/24 6:08 AM, Stanislaw Gruszka wrote:
> PM runtime can be done simultaneously with AER error handling.
> Avoid that by using pm_runtime_get_sync() before and pm_runtime_put()
> after reset in pcie_do_recovery() for all recovering devices.
>
> pm_runtime_get_sync() will increase dev->power.usage_count counter
> to prevent any possible future request to runtime suspend a device,
> as well as resume device is was in D3hot state.
runtime suspend a device or resume a device that was in D3hot state.
>
> I tested with igc device by doing simultaneous aer_inject and
> rpm suspend/resume via /sys/bus/pci/devices/PCI_ID/power/control
> and can reproduce:
>
> igc 0000:02:00.0: not ready 65535ms after bus reset; giving up
> pcieport 0000:00:1c.2: AER: Root Port link has been reset (-25)
> pcieport 0000:00:1c.2: AER: subordinate device reset failed
> pcieport 0000:00:1c.2: AER: device recovery failed
> igc 0000:02:00.0: Unable to change power state from D3hot to D0, device inaccessible
>
> The problem disappears when applied this patch.
>
> Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
> ---

since it is a bug fix, may be Cc: stable@vger.kernel.org

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> RFC -> v1:
>  add runtime callbacks to pcie_do_recovery(), this covers DPC case
>  as well as case of recovering multiple devices under same port.
>  
>  drivers/pci/pcie/err.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index 59c90d04a609..705893b5f7b0 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -13,6 +13,7 @@
>  #define dev_fmt(fmt) "AER: " fmt
>  
>  #include <linux/pci.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/module.h>
>  #include <linux/kernel.h>
>  #include <linux/errno.h>
> @@ -85,6 +86,18 @@ static int report_error_detected(struct pci_dev *dev,
>  	return 0;
>  }
>  
> +static int pci_pm_runtime_get_sync(struct pci_dev *pdev, void *data)
> +{
> +	pm_runtime_get_sync(&pdev->dev);
> +	return 0;
> +}
> +
> +static int pci_pm_runtime_put(struct pci_dev *pdev, void *data)
> +{
> +	pm_runtime_put(&pdev->dev);
> +	return 0;
> +}
> +
>  static int report_frozen_detected(struct pci_dev *dev, void *data)
>  {
>  	return report_error_detected(dev, pci_channel_io_frozen, data);
> @@ -207,6 +220,8 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>  	else
>  		bridge = pci_upstream_bridge(dev);
>  
> +	pci_walk_bridge(bridge, pci_pm_runtime_get_sync, NULL);
> +
>  	pci_dbg(bridge, "broadcast error_detected message\n");
>  	if (state == pci_channel_io_frozen) {
>  		pci_walk_bridge(bridge, report_frozen_detected, &status);
> @@ -251,10 +266,15 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>  		pcie_clear_device_status(dev);
>  		pci_aer_clear_nonfatal_status(dev);
>  	}
> +
> +	pci_walk_bridge(bridge, pci_pm_runtime_put, NULL);
> +
>  	pci_info(bridge, "device recovery successful\n");
>  	return status;
>  
>  failed:
> +	pci_walk_bridge(bridge, pci_pm_runtime_put, NULL);
> +
>  	pci_uevent_ers(bridge, PCI_ERS_RESULT_DISCONNECT);
>  
>  	/* TODO: Should kernel panic here? */

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer