Re: [PATCH v4 2/3] PCI/DPC: Run recovery on device that detected the error

[Shuai Xue <xueshuai@linux.alibaba.com>]

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@linux.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