Re: [PATCH v5] PCI: hotplug: Add a generic RAS tracepoint for hotplug event

Steven Rostedt
2025-01-13T20:55:06Z

On Thu, 9 Jan 2025 10:55:43 +0800
Shuai Xue <xueshuai@linux.alibaba.com> wrote:

> 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")

Since you are creating these enums in this patch, you can also do a
shortcut here too. Instead of doing the define here, move it to
include/uapi/linux/pci.h:

> +
> +/* 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,
> +};

Instead of defining the enum as you did above, if you have the define of
the enums here, you could do:

#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")

#undef EM
#undef EMe
#define EM(a, b) a,
#define EMe(a, b) a,

enum pci_hotplug_event {
PCI_HOTPLUG_EVENT
};

Then you only have one place to worry about adding new enums ;-)

-- Steve

> +
> #endif /* _UAPILINUX_PCI_H */