Re: [PATCH v5 6/8] PCI/AER: Introduce ratelimit for error logs

[Karolina Stolarek <karolina.stolarek@oracle.com>]

On 21/03/2025 02:58, Jon Pan-Doh wrote:
 >
>   
>   void aer_print_error(struct pci_dev *dev, struct aer_err_info *info,
> -		     const char *level)
> +		     const char *level, bool ratelimited)

Ideally, we would like to be able to extract the "ratelimited" flag from 
the aer_err_info struct, with no need for extra parameters in this function.

>   static void aer_print_rp_info(struct pci_dev *rp, struct aer_err_info *info)
>   {
>   	u8 bus = info->id >> 8;
>   	u8 devfn = info->id & 0xff;
> +	struct pci_dev *dev;
> +	bool ratelimited = false;
> +	int i;
>   
> -	pci_info(rp, "%s%s error message received from %04x:%02x:%02x.%d\n",
> -		 info->multi_error_valid ? "Multiple " : "",
> -		 aer_error_severity_string[info->severity],
> -		 pci_domain_nr(rp->bus), bus, PCI_SLOT(devfn),
> -		 PCI_FUNC(devfn));
> +	/* extract endpoint device ratelimit */
> +	for (i = 0; i < info->error_dev_num; i++) {
> +		dev = info->dev[i];
> +		if (info->id == pci_dev_id(dev)) {
> +			ratelimited = info->ratelimited[i];
> +			break;
> +		}
> +	}

(please correct me if I'm misreading the patch)

It looks like we ratelimit the Root Port logs based on the source device 
that generated the message, and the actual errors in 
aer_process_err_devices() use their own ratelimits. As you noted in one 
of your emails, there might be the case where we report errors but 
there's no information about the Root Port that issued the interrupt 
we're handling.

The way I understood the suggestion in 20250320202913.GA1097165@bhelgaas 
is that we evaluate the ratelimit of the Root Port or Downstream Port, 
save it in aer_err_info, and use it in aer_print_rp_info() and 
aer_print_error(). I'm worried that one noisy device under a Root Port 
could hit a ratelimit and hide everything else

A fair (and complicated) solution would be to check the ratelimits of 
all devices in the Error Message to see if there is at least one that 
can be reported. If so, use that ratelimit when printing both the Root 
Port info and the error details from that device.

This is to say that if we keep aer_print_rp_info() (which was decided a 
couple emails ago), we should print it before any error coming from that 
Root Port is reported.

All the best,
Karolina