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PCI: trace: Add generic RAS tracepoint for hotplug event

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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 <lukas@wunner.de>
Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> # for trace event
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://patch.msgid.link/20251210132907.58799-2-xueshuai@linux.alibaba.com
This commit is contained in:
Shuai Xue 2025-12-10 21:29:05 +08:00 committed by Bjorn Helgaas
parent 8f0b4cce44
commit 9e541b3cee
5 changed files with 118 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/pci/Makefile
View File

@ -47,3 +47,6 @@ obj-y += controller/
obj-y += switch/
subdir-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG
CFLAGS_trace.o := -I$(src)
obj-$(CONFIG_TRACING) += trace.o

31
drivers/pci/hotplug/pciehp_ctrl.c
View File

@ -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);
}
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:

11
drivers/pci/trace.c Normal file
View File

@ -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>

72
include/trace/events/pci.h Normal file
View File

@ -0,0 +1,72 @@
/* 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}
/*
* Note: For generic PCI hotplug events, we pass already-resolved strings
* (port_name, slot) instead of driver-specific structures like 'struct
* controller'. This is because different PCI hotplug drivers (pciehp, cpqphp,
* ibmphp, shpchp) define their own versions of 'struct controller' with
* different fields and helper functions. Using driver-specific structures would
* make the tracepoint interface non-generic and cause compatibility issues
* across different drivers.
*/
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_fast_assign(
__assign_str(port_name);
__assign_str(slot);
__entry->event = event;
),
TP_printk("%s slot:%s, event:%s\n",
__get_str(port_name),
__get_str(slot),
__print_symbolic(__entry->event, PCI_HOTPLUG_EVENT)
)
);
#endif /* _TRACE_HW_EVENT_PCI_H */
/* This part must be outside protection */
#include <trace/define_trace.h>

7
include/uapi/linux/pci.h
View File

@ -39,4 +39,11 @@
#define PCIIOC_MMAP_IS_MEM (PCIIOC_BASE | 0x02) /* Set mmap state to MEM space. */
#define PCIIOC_WRITE_COMBINE (PCIIOC_BASE | 0x03) /* Enable/disable write-combining. */
enum pci_hotplug_event {
PCI_HOTPLUG_LINK_UP,
PCI_HOTPLUG_LINK_DOWN,
PCI_HOTPLUG_CARD_PRESENT,
PCI_HOTPLUG_CARD_NOT_PRESENT,
};
#endif /* _UAPILINUX_PCI_H */