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 > + > + 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> > 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 */
