Re: [PATCH RESEND] PCI/AER: Use a common function to print AER error bits

[Alex G.]

On 04/27/2018 05:43 PM, Bjorn Helgaas wrote:
> On Tue, Apr 17, 2018 at 12:09:43PM -0500, Alexandru Gagniuc wrote:
> > On errors reported from CPER, cper_print_bits() was used to log the
> > AER bits. This resulted in hard-to-understand messages, without a
> > prefix. Instead use __aer_print_error() for both native AER and CPER
> > to provide a more consistent log format.
> >
> > Signed-off-by: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
> > ---
> >   drivers/pci/pcie/aer/aerdrv_errprint.c | 16 +++++++++-------
> >   1 file changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/aer/aerdrv_errprint.c b/drivers/pci/pcie/aer/aerdrv_errprint.c
> > index cfc89dd57831..cfae4d52f848 100644
> > --- a/drivers/pci/pcie/aer/aerdrv_errprint.c
> > +++ b/drivers/pci/pcie/aer/aerdrv_errprint.c
> > @@ -216,28 +216,30 @@ EXPORT_SYMBOL_GPL(cper_severity_to_aer);
> >   void cper_print_aer(struct pci_dev *dev, int aer_severity,
> >   		    struct aer_capability_regs *aer)
> >   {
> > -	int layer, agent, status_strs_size, tlp_header_valid = 0;
> > +	int layer, agent, tlp_header_valid = 0;
> >   	u32 status, mask;
> > -	const char **status_strs;
> > +	struct aer_err_info info;
> >   
> >   	if (aer_severity == AER_CORRECTABLE) {
> >   		status = aer->cor_status;
> >   		mask = aer->cor_mask;
> > -		status_strs = aer_correctable_error_string;
> > -		status_strs_size = ARRAY_SIZE(aer_correctable_error_string);
> >   	} else {
> >   		status = aer->uncor_status;
> >   		mask = aer->uncor_mask;
> > -		status_strs = aer_uncorrectable_error_string;
> > -		status_strs_size = ARRAY_SIZE(aer_uncorrectable_error_string);
> >   		tlp_header_valid = status & AER_LOG_TLP_MASKS;
> >   	}
> >   
> >   	layer = AER_GET_LAYER_ERROR(aer_severity, status);
> >   	agent = AER_GET_AGENT(aer_severity, status);
> >   
> > +	memset(&info, 0, sizeof(info));
> > +	info.severity = aer_severity;
> > +	info.status = status;
> > +	info.mask = mask;
> > +	info.first_error = 0x1f;
>
> I like this patch a lot, but where does this "first_error = 0x1f" come
> from?

aer_(un)correctable_error_string don't go to [0x1f], so this guarantees 
us we don't print "(First)".

> I assume this is supposed to be the "First Error Pointer" in the
> Advanced Error Capabilities and Control register (PCIe r4.0, sec
> 7.8.4.7).  There is a "cap_control" field in struct
> aer_capability_regs; should we be using that here?

There is a way to extract it from the PCI regs, and it's quite simple. 
IIRC, it should be all f's when the capability is not implemented. I 
wanted to avoid any further parsing of PCI regs in this patch.

I can see a way to use even more common printk code, but that requires 
validating the PCI regs we get from firmware. That means we need to make 
a guarantee about CPER that is beyond the scope of this patch.

Alex

> > +
> >   	pci_err(dev, "aer_status: 0x%08x, aer_mask: 0x%08x\n", status, mask);
> > -	cper_print_bits("", status, status_strs, status_strs_size);
> > +	__aer_print_error(dev, &info);
> >   	pci_err(dev, "aer_layer=%s, aer_agent=%s\n",
> >   		aer_error_layer[layer], aer_agent_string[agent]);
> >   
> > --
> > 2.14.3