linux-kernel - Re: [PATCH v15 1/5] PCI/ERR: Update error status after reset

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Message-ID: <20200226134150.GA107992@google.com>
Date:   Wed, 26 Feb 2020 07:41:50 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     sathyanarayanan.kuppuswamy@...ux.intel.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        ashok.raj@...el.com, Keith Busch <keith.busch@...el.com>
Subject: Re: [PATCH v15 1/5] PCI/ERR: Update error status after reset_link()

On Thu, Feb 13, 2020 at 10:20:13AM -0800, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 
> Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") uses
> reset_link() to recover from fatal errors. But during fatal error
> recovery, if the initial value of error status is
> PCI_ERS_RESULT_DISCONNECT or PCI_ERS_RESULT_NO_AER_DRIVER then
> even after successful recovery (using reset_link()) pcie_do_recovery()
> will report the recovery result as failure. So update the status of
> error after reset_link().
> 
> Fixes: bdb5ac85777d ("PCI/ERR: Handle fatal error recovery")
> Cc: Ashok Raj <ashok.raj@...el.com>
> Cc: Keith Busch <keith.busch@...el.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> Acked-by: Keith Busch <keith.busch@...el.com>

I raised the possibility of a stable tag for this.  If you'd like
that, please add the tag and some justification per
Documentation/process/stable-kernel-rules.rst.

A kernel.org bugzilla pointer to show the user-visible effect of this,
e.g., "lspci -vv" and a dmesg log showing an error that should be
recoverable but isn't, would be a good start.  That would actually be
useful even if you don't want a stable tag.

> ---
>  drivers/pci/pcie/err.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index 01dfc8bb7ca0..eefefe03857a 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -208,9 +208,11 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state,
>  	else
>  		pci_walk_bus(bus, report_normal_detected, &status);
>  
> -	if (state == pci_channel_io_frozen &&
> -	    reset_link(dev, service) != PCI_ERS_RESULT_RECOVERED)
> -		goto failed;
> +	if (state == pci_channel_io_frozen) {
> +		status = reset_link(dev, service);
> +		if (status != PCI_ERS_RESULT_RECOVERED)
> +			goto failed;
> +	}
>  
>  	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
>  		status = PCI_ERS_RESULT_RECOVERED;
> -- 
> 2.21.0
>