Re: [PATCH v7 2/5] PCI/DPC: Run recovery on device that detected the error

Jonathan Cameron
2026-01-27T10:24:14Z

On Sat, 24 Jan 2026 15:45:54 +0800
Shuai Xue <xueshuai@linux.alibaba.com> wrote:

> The current implementation of pcie_do_recovery() assumes that the
> recovery process is executed for the device that detected the error.
> However, the DPC driver currently passes the error port that experienced
> the DPC event to pcie_do_recovery().
>
> Use the SOURCE ID register to correctly identify the device that
> detected the error. When passing the error device, the
> pcie_do_recovery() will find the upstream bridge and walk bridges
> potentially AER affected. And subsequent commits will be able to
> accurately access AER status of the error device.
>
> Should not observe any functional changes.
>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
> ---
> drivers/pci/pci.h | 2 +-
> drivers/pci/pcie/dpc.c | 25 +++++++++++++++++++++----
> drivers/pci/pcie/edr.c | 7 ++++---
> 3 files changed, 26 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 0e67014aa001..58640e656897 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -771,7 +771,7 @@ struct rcec_ea {
> void pci_save_dpc_state(struct pci_dev *dev);
> void pci_restore_dpc_state(struct pci_dev *dev);
> void pci_dpc_init(struct pci_dev *pdev);
> -void dpc_process_error(struct pci_dev *pdev);
> +struct pci_dev *dpc_process_error(struct pci_dev *pdev);
> pci_ers_result_t dpc_reset_link(struct pci_dev *pdev);
> bool pci_dpc_recovered(struct pci_dev *pdev);
> unsigned int dpc_tlp_log_len(struct pci_dev *dev);
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index bff29726c6a5..f6069f621683 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -260,10 +260,20 @@ static int dpc_get_aer_uncorrect_severity(struct pci_dev *dev,
> return 1;
> }
>
> -void dpc_process_error(struct pci_dev *pdev)
> +/**
> + * dpc_process_error - handle the DPC error status
> + * @pdev: the port that experienced the containment event
> + *
> + * Return: the device that detected the error.
> + *
> + * NOTE: The device reference count is increased, the caller must decrement
> + * the reference count by calling pci_dev_put().
> + */
> +struct pci_dev *dpc_process_error(struct pci_dev *pdev)

Maybe it makes sense to carry the err_port naming for the pci_dev
in here as well? Seems stronger than just relying on people
reading the documentation you've added.

> {
> u16 cap = pdev->dpc_cap, status, source, reason, ext_reason;
> struct aer_err_info info = {};
> + struct pci_dev *err_dev;
>
> pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
>
> @@ -279,6 +289,7 @@ void dpc_process_error(struct pci_dev *pdev)
> pci_aer_clear_nonfatal_status(pdev);
> pci_aer_clear_fatal_status(pdev);
> }
> + err_dev = pci_dev_get(pdev);
> break;
> case PCI_EXP_DPC_STATUS_TRIGGER_RSN_NFE:
> case PCI_EXP_DPC_STATUS_TRIGGER_RSN_FE:
> @@ -290,6 +301,8 @@ void dpc_process_error(struct pci_dev *pdev)
> "ERR_FATAL" : "ERR_NONFATAL",
> pci_domain_nr(pdev->bus), PCI_BUS_NUM(source),
> PCI_SLOT(source), PCI_FUNC(source));
> + err_dev = pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
> + PCI_BUS_NUM(source), source & 0xff);

Bunch of replication in her with the pci_warn(). Maybe some local variables?
Maybe even rebuild the final parameter from PCI_DEVFN(slot, func) just to make the
association with the print really obvious?

Is there any chance that this might return NULL? Feels like maybe that's
only a possibility on a broken setup, but I'm not sure of all the wonderful
races around hotplug and DPC occurring before the OS has caught up.

> break;
> case PCI_EXP_DPC_STATUS_TRIGGER_RSN_IN_EXT:
> ext_reason = status & PCI_EXP_DPC_STATUS_TRIGGER_RSN_EXT;
> @@ -304,8 +317,11 @@ void dpc_process_error(struct pci_dev *pdev)
> if (ext_reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_RP_PIO &&
> pdev->dpc_rp_extensions)
> dpc_process_rp_pio_error(pdev);
> + err_dev = pci_dev_get(pdev);
> break;
> }
> +
> + return err_dev;
> }

> diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
> index 521fca2f40cb..b6e9d652297e 100644
> --- a/drivers/pci/pcie/edr.c
> +++ b/drivers/pci/pcie/edr.c
> @@ -150,7 +150,7 @@ static int acpi_send_edr_status(struct pci_dev *pdev, struct pci_dev *edev,
>
> static void edr_handle_event(acpi_handle handle, u32 event, void *data)
> {
> - struct pci_dev *pdev = data, *err_port;
> + struct pci_dev *pdev = data, *err_port, *err_dev;
> pci_ers_result_t estate = PCI_ERS_RESULT_DISCONNECT;
> u16 status;
>
> @@ -190,7 +190,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
> goto send_ost;
> }
>
> - dpc_process_error(err_port);
> + err_dev = dpc_process_error(err_port);
> pci_aer_raw_clear_status(err_port);
>
> /*
> @@ -198,7 +198,8 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
> * or ERR_NONFATAL, since the link is already down, use the FATAL
> * error recovery path for both cases.
> */
> - estate = pcie_do_recovery(err_port, pci_channel_io_frozen, dpc_reset_link);
> + estate = pcie_do_recovery(err_dev, pci_channel_io_frozen, dpc_reset_link);
> + pci_dev_put(err_dev);
>
> send_ost:
>