linux-kernel - Re: [PATCH] PCI/AER: correctable error message as KERN

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Message-ID: <20230314193836.GA1667748@bhelgaas>
Date:   Tue, 14 Mar 2023 14:38:36 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Grant Grundler <grundler@...omium.org>
Cc:     Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Oliver O 'Halloran <oohall@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, Rajat Jain <rajatja@...omium.org>
Subject: Re: [PATCH] PCI/AER: correctable error message as KERN_INFO

On Tue, Feb 28, 2023 at 10:04:53PM -0800, Grant Grundler wrote:
> Since correctable errors have been corrected (and counted), the dmesg output
> should not be reported as a warning, but rather as "informational".
> 
> Otherwise, using a certain well known vendor's PCIe parts in a USB4 docking
> station, the dmesg buffer can be spammed with correctable errors, 717 bytes
> per instance, potentially many MB per day.
> 
> Given the "WARN" priority, these messages have already confused the typical
> user that stumbles across them, support staff (triaging feedback reports),
> and more than a few linux kernel devs. Changing to INFO will hide these
> messages from most audiences.
> 
> Signed-off-by: Grant Grundler <grundler@...omium.org>
> ---
> This patch will likely conflict with:
>   https://lore.kernel.org/all/20230103165548.570377-1-rajat.khandelwal@linux.intel.com/
> 
> which I'd also like to see upstream. Please let me know to resubmit
> mine if Rajat's patch lands first. Or feel free to fix up this one.

Yes.  I think it makes sense to separate this into two patches:

  1) Log correctable errors as KERN_INFO instead of KERN_WARNING, and

  2) Rate-limit correctable error logging.

>  drivers/pci/pcie/aer.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index f6c24ded134c..e4cf3ec40d66 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -692,7 +692,7 @@ static void __aer_print_error(struct pci_dev *dev,
>  
>  	if (info->severity == AER_CORRECTABLE) {
>  		strings = aer_correctable_error_string;
> -		level = KERN_WARNING;
> +		level = KERN_INFO;
>  	} else {
>  		strings = aer_uncorrectable_error_string;
>  		level = KERN_ERR;
> @@ -724,7 +724,7 @@ void aer_print_error(struct pci_dev *dev, struct aer_err_info *info)
>  	layer = AER_GET_LAYER_ERROR(info->severity, info->status);
>  	agent = AER_GET_AGENT(info->severity, info->status);
>  
> -	level = (info->severity == AER_CORRECTABLE) ? KERN_WARNING : KERN_ERR;
> +	level = (info->severity == AER_CORRECTABLE) ? KERN_INFO : KERN_ERR;
>  
>  	pci_printk(level, dev, "PCIe Bus Error: severity=%s, type=%s, (%s)\n",
>  		   aer_error_severity_string[info->severity],

Shouldn't we do the same in the cper_print_aer() path?  That path
currently uses pci_err() and then calls __aer_print_error(), so the
initial message will always be KERN_ERR, and the decoding done by
__aer_print_error() will be KERN_INFO (for correctable) or KERN_ERR.

Seems like a shame to do the same test in three places, but would
require a little more refactoring to avoid that.

Bjorn