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Message-ID: <7d8bd8d5-63bc-4a52-afa1-b6e3738a188e@linux.alibaba.com>
Date: Thu, 19 Jun 2025 14:28:47 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, bhelgaas@...gle.com, kbusch@...nel.org,
sathyanarayanan.kuppuswamy@...ux.intel.com, mahesh@...ux.ibm.com,
oohall@...il.com, Jonathan.Cameron@...wei.com, terry.bowman@....com,
tianruidong@...ux.alibaba.com
Subject: Re: [PATCH v4 2/3] PCI/DPC: Run recovery on device that detected the
error
在 2025/6/12 18:31, Manivannan Sadhasivam 写道:
> On Mon, Feb 17, 2025 at 10:42:17AM +0800, Shuai Xue wrote:
>> The current implementation of pcie_do_recovery() assumes that the
>> recovery process is executed on the device that detected the error.
>
> s/on/for
>
>> 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 patches will be able to
>
> s/patches/commits
Will fix the typos.
>
>> accurately access AER status of the error device.
>>
>> Should not observe any functional changes.
>>
>> Signed-off-by: Shuai Xue <xueshuai@...ux.alibaba.com>
>> ---
>> drivers/pci/pci.h | 2 +-
>> drivers/pci/pcie/dpc.c | 28 ++++++++++++++++++++++++----
>> drivers/pci/pcie/edr.c | 7 ++++---
>> 3 files changed, 29 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>> index 01e51db8d285..870d2fbd6ff2 100644
>> --- a/drivers/pci/pci.h
>> +++ b/drivers/pci/pci.h
>> @@ -572,7 +572,7 @@ 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 1a54a0b657ae..ea3ea989afa7 100644
>> --- a/drivers/pci/pcie/dpc.c
>> +++ b/drivers/pci/pcie/dpc.c
>> @@ -253,10 +253,20 @@ 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.
>
> s/Return/Return:
>
>> + *
>> + * 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)
>> {
>> 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);
>> pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &source);
>> @@ -279,6 +289,13 @@ void dpc_process_error(struct pci_dev *pdev)
>> "software trigger" :
>> "reserved error");
>>
>> + if (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_NFE ||
>> + reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_FE)
>> + err_dev = pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
>> + PCI_BUS_NUM(source), source & 0xff);
>> + else
>> + err_dev = pci_dev_get(pdev);
>> +
>> /* show RP PIO error detail information */
>> if (pdev->dpc_rp_extensions &&
>> reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_IN_EXT &&
>> @@ -291,6 +308,8 @@ void dpc_process_error(struct pci_dev *pdev)
>> pci_aer_clear_nonfatal_status(pdev);
>> pci_aer_clear_fatal_status(pdev);
>> }
>> +
>> + return err_dev;
>> }
>>
>> static void pci_clear_surpdn_errors(struct pci_dev *pdev)
>> @@ -346,7 +365,7 @@ static bool dpc_is_surprise_removal(struct pci_dev *pdev)
>>
>> static irqreturn_t dpc_handler(int irq, void *context)
>> {
>> - struct pci_dev *err_port = context;
>> + struct pci_dev *err_port = context, *err_dev;
>>
>> /*
>> * According to PCIe r6.0 sec 6.7.6, errors are an expected side effect
>> @@ -357,10 +376,11 @@ static irqreturn_t dpc_handler(int irq, void *context)
>> return IRQ_HANDLED;
>> }
>>
>> - dpc_process_error(err_port);
>> + err_dev = dpc_process_error(err_port);
>>
>> /* We configure DPC so it only triggers on ERR_FATAL */
>> - pcie_do_recovery(err_port, pci_channel_io_frozen, dpc_reset_link);
>> + pcie_do_recovery(err_dev, pci_channel_io_frozen, dpc_reset_link);
>> + pci_dev_put(err_dev);
>>
>> return IRQ_HANDLED;
>> }
>> diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
>> index 521fca2f40cb..088f3e188f54 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 +198,7 @@ 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);
>>
>> send_ost:
>>
>> @@ -216,6 +216,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
>> }
>>
>> pci_dev_put(err_port);
>> + pci_dev_put(err_dev);
>
> err_dev is not a valid pointer before calling dpc_process_error(). So either
> initialize it with NULL or only call it in error paths after
> dpc_process_error().
>
> And btw, pci_dev_put(err_dev) should come before pci_dev_put(err_port).
>
> - Mani
>
You are right.
Will send a new patch to fix it.
Thanks.
Shuai
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