On Tue, 14 Oct 2025 20:31:57 +0800
Shuai Xue <[email protected]> wrote:
Hotplug events are critical indicators for analyzing hardware health,
and surprise link downs can significantly impact system performance and
reliability.
Define a new TRACING_SYSTEM named "pci", add a generic RAS tracepoint
for hotplug event to help health checks. Add enum pci_hotplug_event in
include/uapi/linux/pci.h so applications like rasdaemon can register
tracepoint event handlers for it.
The following output is generated when a device is hotplugged:
$ echo 1 > /sys/kernel/debug/tracing/events/pci/pci_hp_event/enable
$ cat /sys/kernel/debug/tracing/trace_pipe
irq/51-pciehp-88 [001] ..... 1311.177459: pci_hp_event: 0000:00:02.0
slot:10, event:CARD_PRESENT
irq/51-pciehp-88 [001] ..... 1311.177566: pci_hp_event: 0000:00:02.0
slot:10, event:LINK_UP
Suggested-by: Lukas Wunner <[email protected]>
Suggested-by: Steven Rostedt <[email protected]>
Signed-off-by: Shuai Xue <[email protected]>
Reviewed-by: Lukas Wunner <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
---
drivers/pci/Makefile | 3 ++
drivers/pci/hotplug/pciehp_ctrl.c | 31 ++++++++++++---
drivers/pci/trace.c | 11 ++++++
include/trace/events/pci.h | 63 +++++++++++++++++++++++++++++++
include/uapi/linux/pci.h | 7 ++++
5 files changed, 109 insertions(+), 6 deletions(-)
create mode 100644 drivers/pci/trace.c
create mode 100644 include/trace/events/pci.h
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index 67647f1880fb..58a4e4ea76b0 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -45,3 +45,6 @@ obj-y += controller/
obj-y += switch/
subdir-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG
+
+CFLAGS_trace.o := -I$(src)
+obj-$(CONFIG_TRACING) += trace.o
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c
b/drivers/pci/hotplug/pciehp_ctrl.c
index bcc938d4420f..7805f697a02c 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -19,6 +19,7 @@
#include <linux/types.h>
#include <linux/pm_runtime.h>
#include <linux/pci.h>
+#include <trace/events/pci.h>
#include "../pci.h"
#include "pciehp.h"
@@ -244,12 +245,20 @@ void pciehp_handle_presence_or_link_change(struct
controller *ctrl, u32 events)
case ON_STATE:
ctrl->state = POWEROFF_STATE;
mutex_unlock(&ctrl->state_lock);
- if (events & PCI_EXP_SLTSTA_DLLSC)
+ if (events & PCI_EXP_SLTSTA_DLLSC) {
ctrl_info(ctrl, "Slot(%s): Link Down\n",
slot_name(ctrl));
- if (events & PCI_EXP_SLTSTA_PDC)
+ trace_pci_hp_event(pci_name(ctrl->pcie->port),
+ slot_name(ctrl),
+ PCI_HOTPLUG_LINK_DOWN);
I know this is v12 and I don't remember if I suggested this before and you
gave me a reason already, but why not simply pass in "ctrl" and have the
TRACE_EVENT() denote the names?
+ }
+ if (events & PCI_EXP_SLTSTA_PDC) {
ctrl_info(ctrl, "Slot(%s): Card not present\n",
slot_name(ctrl));
+ trace_pci_hp_event(pci_name(ctrl->pcie->port),
+ slot_name(ctrl),
+ PCI_HOTPLUG_CARD_NOT_PRESENT);
+ }
pciehp_disable_slot(ctrl, SURPRISE_REMOVAL);
break;
default:
@@ -269,6 +278,9 @@ void pciehp_handle_presence_or_link_change(struct
controller *ctrl, u32 events)
INDICATOR_NOOP);
ctrl_info(ctrl, "Slot(%s): Card not present\n",
slot_name(ctrl));
+ trace_pci_hp_event(pci_name(ctrl->pcie->port),
+ slot_name(ctrl),
+ PCI_HOTPLUG_CARD_NOT_PRESENT);
}
mutex_unlock(&ctrl->state_lock);
return;
@@ -281,12 +293,19 @@ void pciehp_handle_presence_or_link_change(struct
controller *ctrl, u32 events)
case OFF_STATE:
ctrl->state = POWERON_STATE;
mutex_unlock(&ctrl->state_lock);
- if (present)
+ if (present) {
ctrl_info(ctrl, "Slot(%s): Card present\n",
slot_name(ctrl));
- if (link_active)
- ctrl_info(ctrl, "Slot(%s): Link Up\n",
- slot_name(ctrl));
+ trace_pci_hp_event(pci_name(ctrl->pcie->port),
+ slot_name(ctrl),
+ PCI_HOTPLUG_CARD_PRESENT);
+ }
+ if (link_active) {
+ ctrl_info(ctrl, "Slot(%s): Link Up\n", slot_name(ctrl));
+ trace_pci_hp_event(pci_name(ctrl->pcie->port),
+ slot_name(ctrl),
+ PCI_HOTPLUG_LINK_UP);
+ }
ctrl->request_result = pciehp_enable_slot(ctrl);
break;
default:
diff --git a/drivers/pci/trace.c b/drivers/pci/trace.c
new file mode 100644
index 000000000000..cf11abca8602
--- /dev/null
+++ b/drivers/pci/trace.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Tracepoints for PCI system
+ *
+ * Copyright (C) 2025 Alibaba Corporation
+ */
+
+#include <linux/pci.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/pci.h>
diff --git a/include/trace/events/pci.h b/include/trace/events/pci.h
new file mode 100644
index 000000000000..208609492c06
--- /dev/null
+++ b/include/trace/events/pci.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM pci
+
+#if !defined(_TRACE_HW_EVENT_PCI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_HW_EVENT_PCI_H
+
+#include <linux/tracepoint.h>
+
+#define PCI_HOTPLUG_EVENT \
+ EM(PCI_HOTPLUG_LINK_UP, "LINK_UP") \
+ EM(PCI_HOTPLUG_LINK_DOWN, "LINK_DOWN") \
+ EM(PCI_HOTPLUG_CARD_PRESENT, "CARD_PRESENT") \
+ EMe(PCI_HOTPLUG_CARD_NOT_PRESENT, "CARD_NOT_PRESENT")
+
+/* Enums require being exported to userspace, for user tool parsing */
+#undef EM
+#undef EMe
+#define EM(a, b) TRACE_DEFINE_ENUM(a);
+#define EMe(a, b) TRACE_DEFINE_ENUM(a);
+
+PCI_HOTPLUG_EVENT
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings
+ * that will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a, b) {a, b},
+#define EMe(a, b) {a, b}
+
+TRACE_EVENT(pci_hp_event,
+
+ TP_PROTO(const char *port_name,
+ const char *slot,
+ const int event),
+
+ TP_ARGS(port_name, slot, event),
+
+ TP_STRUCT__entry(
+ __string( port_name, port_name )
+ __string( slot, slot )
+ __field( int, event )
+ ),
TP_PROTO(struct controller *ctrl, int event),
TP_ARGS(ctrl, event),
TP_STRUCT__entry(
__string( port_name, pci_name(ctrl->pcie->port)
)
__string( slot, slot_name(ctrl)
)
__field( int, event
)
),
It would move the work out of the calling path.
-- Steve
