[PATCH v7] PCI: hotplug: Add a generic RAS tracepoint for hotplug event
From: Shuai Xue <xueshuai@linux.alibaba.com>
Date: 2025-05-07 01:16:10
Also in:
linux-edac, linux-pci, lkml
Subsystem:
pci subsystem, the rest · Maintainers:
Bjorn Helgaas, Linus Torvalds
Hotplug events are critical indicators for analyzing hardware health,
particularly in AI supercomputers where surprise link downs can
significantly impact system performance and reliability.
To this end, define a new TRACING_SYSTEM named pci, add a generic RAS
tracepoint for hotplug event to help healthy check, and generate
tracepoints for pcie hotplug event. Add enum pci_hotplug_event in
include/uapi/linux/pci.h so applications like rasdaemon can register
tracepoint event handlers for it.
The output like below:
$ echo 1 > /sys/kernel/debug/tracing/events/pci/pci_hp_event/enable
$ cat /sys/kernel/debug/tracing/trace_pipe
<...>-206 [001] ..... 40.373870: pci_hp_event: 0000:00:02.0 slot:10, event:Link Down
<...>-206 [001] ..... 40.374871: pci_hp_event: 0000:00:02.0 slot:10, event:Card not present
Suggested-by: Lukas Wunner <lukas@wunner.de>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
---
changes since v6:
- move defination of tracepoint enum back to trace.h. Otherwise, it will
cause a build error when CONFIG_UAPI_HEADER_TEST=y. The problem is that
the PCI_HOTPLUG_EVENT macro needs to include "linux/tracepoint.h" but it
is not allowed in userspace.
- No code changes compared to v5.
change since v5:
- move define of enum to include/uapi/linux/pci.h
- link: https://lore.kernel.org/lkml/202501190108.tRReJA1Z-lkp@intel.com/ (local)
v5:
- link: https://patchwork.kernel.org/project/linux-pci/patch/20250109025543.56830-1-xueshuai@linux.alibaba.com/
---
drivers/pci/hotplug/pciehp_ctrl.c | 33 ++++++++++++---
drivers/pci/hotplug/trace.h | 68 +++++++++++++++++++++++++++++++
include/uapi/linux/pci.h | 7 ++++
3 files changed, 102 insertions(+), 6 deletions(-)
create mode 100644 drivers/pci/hotplug/trace.h
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index d603a7aa7483..f9beb4d3a9b8 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c@@ -23,6 +23,9 @@ #include "../pci.h" #include "pciehp.h" +#define CREATE_TRACE_POINTS +#include "trace.h" + /* The following routines constitute the bulk of the hotplug controller logic */
@@ -244,12 +247,20 @@ 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 +280,9 @@ 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 +295,19 @@ 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/hotplug/trace.h b/drivers/pci/hotplug/trace.h
new file mode 100644
index 000000000000..5b60cd7bcffb
--- /dev/null
+++ b/drivers/pci/hotplug/trace.h@@ -0,0 +1,68 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#if !defined(_TRACE_HW_EVENT_PCI_HP_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_HW_EVENT_PCI_HP_H + +#include <linux/tracepoint.h> + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM pci + +#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_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_HP_H */ + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH ../../drivers/pci/hotplug +#undef TRACE_INCLUDE_FILE +#define TRACE_INCLUDE_FILE trace + +/* This part must be outside protection */ +#include <trace/define_trace.h>
diff --git a/include/uapi/linux/pci.h b/include/uapi/linux/pci.h
index a769eefc5139..4f150028965d 100644
--- a/include/uapi/linux/pci.h
+++ b/include/uapi/linux/pci.h@@ -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 */
--
2.39.3