PCI/AER: Iterate over error counters instead of error strings

Previously we iterated over AER stat *names*, e.g.,
aer_correctable_error_string[32], but the actual stat *counters* may not be
that large, e.g., pdev->aer_stats->dev_cor_errs[16], which means that we
printed junk in the sysfs stats files.

Iterate over the stat counter arrays instead of the names to avoid this
junk.

Also, added a build time check to make sure all
counters have entries in strings array.

Fixes: 0678e310 ("PCI/AER: Simplify __aer_print_error()")
Link: https://lore.kernel.org/r/20220509181441.31884-1-mkhalfella@purestorage.comReported-by: Meeta Saggi <msaggi@purestorage.com>
Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Meeta Saggi <msaggi@purestorage.com>
Reviewed-by: Eric Badger <ebadger@purestorage.com>
Cc: stable@vger.kernel.org

drivers/pci/pcie/aer.c

@@ -543,7 +543,7 @@ static const char *aer_agent_string[] = {
 	u64 *stats = pdev->aer_stats->stats_array;			\
 	size_t len = 0;							\
 									\
-	for (i = 0; i < ARRAY_SIZE(strings_array); i++) {		\
+	for (i = 0; i < ARRAY_SIZE(pdev->aer_stats->stats_array); i++) {\
 		if (strings_array[i])					\
 			len += sysfs_emit_at(buf, len, "%s %llu\n",	\
 					     strings_array[i],		\
@@ -1349,6 +1349,11 @@ 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);
+
 	/* Limit to Root Ports or Root Complex Event Collectors */
 	if ((pci_pcie_type(port) != PCI_EXP_TYPE_RC_EC) &&
 	    (pci_pcie_type(port) != PCI_EXP_TYPE_ROOT_PORT))