[PATCH v2 5/8] PCI/AER: Introduce ratelimit for error logs

[Jon Pan-Doh <pandoh@google.com>]

Spammy devices can flood kernel logs with AER errors and slow/stall
execution. Add per-device ratelimits for AER errors (correctable and
uncorrectable). Set the default rate to the default kernel ratelimit
(10 per 5s).

Tested using aer-inject[1]. Sent 11 AER errors. Observed 10 errors logged
while AER stats (cat /sys/bus/pci/devices/<dev>/aer_dev_correctable) show
true count of 11.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/gong.chen/aer-inject.git

Signed-off-by: Jon Pan-Doh <pandoh@google.com>
---
 drivers/pci/pcie/aer.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index b4f902fd5ef6..c5b5381e2930 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -28,6 +28,7 @@
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/kfifo.h>
+#include <linux/ratelimit.h>
 #include <linux/slab.h>
 #include <acpi/apei.h>
 #include <acpi/ghes.h>
@@ -88,6 +89,10 @@ struct aer_report {
 	u64 rootport_total_cor_errs;
 	u64 rootport_total_fatal_errs;
 	u64 rootport_total_nonfatal_errs;
+
+	/* Ratelimits for errors */
+	struct ratelimit_state cor_log_ratelimit;
+	struct ratelimit_state uncor_log_ratelimit;
 };
 
 #define AER_LOG_TLP_MASKS		(PCI_ERR_UNC_POISON_TLP|	\
@@ -378,6 +383,10 @@ void pci_aer_init(struct pci_dev *dev)
 		return;
 
 	dev->aer_report = kzalloc(sizeof(struct aer_report), GFP_KERNEL);
+	ratelimit_state_init(&dev->aer_report->cor_log_ratelimit,
+			     DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
+	ratelimit_state_init(&dev->aer_report->uncor_log_ratelimit,
+			     DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
 
 	/*
 	 * We save/restore PCI_ERR_UNCOR_MASK, PCI_ERR_UNCOR_SEVER,
@@ -697,6 +706,7 @@ void aer_print_error(struct pci_dev *dev, struct aer_err_info *info,
 {
 	int layer, agent;
 	int id = pci_dev_id(dev);
+	struct ratelimit_state *ratelimit;
 
 	if (!info->status) {
 		pci_err(dev, "PCIe Bus Error: severity=%s, type=Inaccessible, (Unregistered Agent ID)\n",
@@ -704,6 +714,14 @@ void aer_print_error(struct pci_dev *dev, struct aer_err_info *info,
 		goto out;
 	}
 
+	if (info->severity == AER_CORRECTABLE)
+		ratelimit = &dev->aer_report->cor_log_ratelimit;
+	else
+		ratelimit = &dev->aer_report->uncor_log_ratelimit;
+
+	if (!__ratelimit(ratelimit))
+		return;
+
 	layer = AER_GET_LAYER_ERROR(info->severity, info->status);
 	agent = AER_GET_AGENT(info->severity, info->status);
 
@@ -749,12 +767,15 @@ void pci_print_aer(struct pci_dev *dev, int aer_severity,
 	u32 status, mask;
 	const char *level;
 	struct aer_err_info info;
+	struct ratelimit_state *ratelimit;
 
 	if (aer_severity == AER_CORRECTABLE) {
+		ratelimit = &dev->aer_report->cor_log_ratelimit;
 		status = aer->cor_status;
 		mask = aer->cor_mask;
 		level = KERN_WARNING;
 	} else {
+		ratelimit = &dev->aer_report->uncor_log_ratelimit;
 		status = aer->uncor_status;
 		mask = aer->uncor_mask;
 		tlp_header_valid = status & AER_LOG_TLP_MASKS;
@@ -772,6 +793,9 @@ void pci_print_aer(struct pci_dev *dev, int aer_severity,
 
 	pci_dev_aer_stats_incr(dev, &info);
 
+	if (!__ratelimit(ratelimit))
+		return;
+
 	aer_printk(level, dev, "aer_status: 0x%08x, aer_mask: 0x%08x\n", status, mask);
 	__aer_print_error(dev, &info, level);
 	aer_printk(level, dev, "aer_layer=%s, aer_agent=%s\n",
-- 
2.48.1.601.g30ceb7b040-goog