linux-kernel - Re: [PATCH] PCI/AER: Iterate over error counters instead of error

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Message-Id: <20220603221247.5118-1-mkhalfella@purestorage.com>
Date:   Fri,  3 Jun 2022 22:12:47 +0000
From:   Mohamed Khalfella <mkhalfella@...estorage.com>
To:     mkhalfella@...estorage.com
Cc:     bhelgaas@...gle.com, ebadger@...estorage.com, helgaas@...nel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, msaggi@...estorage.com,
        oohall@...il.com, rajatja@...gle.com, ruscur@...sell.cc,
        stable@...r.kernel.org
Subject: Re: [PATCH] PCI/AER: Iterate over error counters instead of error

Is there any chance for this to land in 5.19?

On 5/10/22 14:17, Mohamed Khalfella wrote:
> > Thanks for catching this; it definitely looks like a real issue!  I
> > guess you're probably seeing junk in the sysfs files?
> 
> That is correct. The initial report was seeing junk when reading sysfs
> files. As descibed, this is happening because we reading data past the
> end of the stats counters array.
> 
> 
> > I think maybe we should populate the currently NULL entries in the
> > string[] arrays and simplify the code here, e.g.,
> > 
> > static const char *aer_correctable_error_string[] = {
> >        "RxErr",                        /* Bit Position 0       */
> >        "dev_cor_errs_bit[1]",
> >	...
> >
> >  if (stats[i])
> >    len += sysfs_emit_at(buf, len, "%s %llu\n", strings_array[i], stats[i]);
> 
> Doing it this way will change the output format. In this case we will show
> stats only if their value is greater than zero. The current code shows all the
> stats those have names (regardless of their value) plus those have non-zero
> values.
> 
> >> @@ -1342,6 +1342,11 @@ static int aer_probe(struct pcie_device *dev)
> >>  	struct device *device = &dev->device;
> >>  	struct pci_dev *port = dev->port;
> >>
> >> +	BUILD_BUG_ON(ARRAY_SIZE(aer_correctable_error_string) <
> >> +		     AER_MAX_TYPEOF_COR_ERRS);
> >> +	BUILD_BUG_ON(ARRAY_SIZE(aer_uncorrectable_error_string) <
> >> +		     AER_MAX_TYPEOF_UNCOR_ERRS);
> >
> > And make these check for "!=" instead of "<".

I am happy to remove these BUILD_BUG_ON() if you think it is a good
idea to do so.

> 
> This will require unnecessarily extending stats arrays to have 32 entries
> in order to match names arrays. If you don't feel strogly about changing
> "<" to "!=", I prefer to keep the code as it is.