linux-kernel - Re: [RESEND PATCH v3 1/1] PCI/ERR: don't clobber status after reset

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Date:   Thu, 15 Oct 2020 16:32:33 +0100
From:   Hedi Berriche <hedi.berriche@....com>
To:     Sinan Kaya <okaya@...nel.org>
Cc:     sathyanarayanan.kuppuswamy@...ux.intel.com,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        Russ Anderson <rja@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Joerg Roedel <jroedel@...e.com>, stable@...nel.org
Subject: Re: [RESEND PATCH v3 1/1] PCI/ERR: don't clobber status after
 reset_link()

On Sun, Oct 11, 2020 at 18:56 Sinan Kaya wrote:
>On 10/10/2020 6:16 PM, Hedi Berriche wrote:
>> Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
>> broke pcie_do_recovery(): updating status after reset_link() has the ill
>> side effect of causing recovery to fail if the error status is
>> PCI_ERS_RESULT_CAN_RECOVER or PCI_ERS_RESULT_NEED_RESET as the following
>> code will *never* run in the case of a successful reset_link()
>>
>>    177         if (status == PCI_ERS_RESULT_CAN_RECOVER) {
>>    ...
>>    181         }
>>
>>    183         if (status == PCI_ERS_RESULT_NEED_RESET) {
>>    ...
>>    192         }
>>
>> For instance in the case of PCI_ERS_RESULT_NEED_RESET we end up not
>> calling ->slot_reset() (because we skip report_slot_reset()) thus
>> breaking driver (re)initialisation.
>>
>> Don't clobber status with the return value of reset_link(); set status
>> to PCI_ERS_RESULT_RECOVERED, in case of successful link reset, if and
>> only if the initial value of error status is PCI_ERS_RESULT_DISCONNECT
>> or PCI_ERS_RESULT_NO_AER_DRIVER.
>>
>> Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
>> Signed-off-by: Hedi Berriche <hedi.berriche@....com>
>> Cc: Russ Anderson <rja@....com>
>> Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
>> Cc: Ashok Raj <ashok.raj@...el.com>
>> Cc: Joerg Roedel <jroedel@...e.com>
>>
>> Cc: stable@...nel.org # v5.7+
>> ---
>>  drivers/pci/pcie/err.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
>> index c543f419d8f9..2730826cfd8a 100644
>> --- a/drivers/pci/pcie/err.c
>> +++ b/drivers/pci/pcie/err.c
>> @@ -165,10 +165,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>  	pci_dbg(dev, "broadcast error_detected message\n");
>>  	if (state == pci_channel_io_frozen) {
>>  		pci_walk_bus(bus, report_frozen_detected, &status);
>> -		status = reset_link(dev);
>> -		if (status != PCI_ERS_RESULT_RECOVERED) {
>> +		if (reset_link(dev) != PCI_ERS_RESULT_RECOVERED) {
>>  			pci_warn(dev, "link reset failed\n");
>>  			goto failed;
>> +		} else {
>> +			if (status == PCI_ERS_RESULT_DISCONNECT ||
>> +			    status == PCI_ERS_RESULT_NO_AER_DRIVER)
>> +				status = PCI_ERS_RESULT_RECOVERED;
>>  		}
>>  	} else {
>>  		pci_walk_bus(bus, report_normal_detected, &status);
>>
>
>Reviewed-by: Sinan Kaya <okaya@...nel.org>

Thanks for the Reviewed-by, Sinan.

Folks,

Any further comments or is this ripe for acceptance?

Cheers,
Hedi.
-- 
Be careful of reading health books, you might die of a misprint.
	-- Mark Twain