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Subject: Re: [RESEND PATCH v3 1/1] PCI/ERR: don't clobber status after
 reset_link()
To:     Hedi Berriche <hedi.berriche@hpe.com>,
        sathyanarayanan.kuppuswamy@linux.intel.com
Cc:     linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        Russ Anderson <rja@hpe.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Ashok Raj <ashok.raj@intel.com>,
        Joerg Roedel <jroedel@suse.com>, stable@kernel.org
References: <20201010221653.2782993-1-hedi.berriche@hpe.com>
 <20201010221653.2782993-2-hedi.berriche@hpe.com>
From:   Sinan Kaya <okaya@kernel.org>
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Message-ID: <5f5eeaf4-4638-6718-1ec9-002d6753e73f@kernel.org>
Date:   Sun, 11 Oct 2020 13:56:13 -0400
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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@hpe.com>
> Cc: Russ Anderson <rja@hpe.com>
> Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Ashok Raj <ashok.raj@intel.com>
> Cc: Joerg Roedel <jroedel@suse.com>
> 
> Cc: stable@kernel.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@kernel.org>