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

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Message-ID: <deb6f0c4-77b8-431e-9b81-555a8344c750@linux.alibaba.com>
Date: Mon, 10 Mar 2025 11:59:55 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: lukas@...ner.de, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-edac@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 helgaas@...nel.org, bhelgaas@...gle.com, tony.luck@...el.com, bp@...en8.de,
 mhiramat@...nel.org, mathieu.desnoyers@...icios.com, oleg@...hat.com,
 naveen@...nel.org, davem@...emloft.net, anil.s.keshavamurthy@...el.com,
 mark.rutland@....com, peterz@...radead.org, tianruidong@...ux.alibaba.com
Subject: Re: [PATCH v5] PCI: hotplug: Add a generic RAS tracepoint for hotplug
 event



在 2025/1/14 04:55, Steven Rostedt 写道:
> On Thu,  9 Jan 2025 10:55:43 +0800
> Shuai Xue <xueshuai@...ux.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 ;-)

Hi, Steve,

If I move PCI_HOTPLUG_EVENT into one place, `include/upai/linux/pci.h`,
I need to include:

     #include <linux/tracepoint.h>

Then, kernel build fails with CONFIG_UAPI_HEADER_TEST=y:

$ make -j128
   DESCEND objtool
   CALL    scripts/checksyscalls.sh
   INSTALL libsubcmd_headers
   HDRTEST usr/include/linux/pci.h
In file included from <command-line>:32:
./usr/include/linux/pci.h:22:10: fatal error: linux/tracepoint.h: No such file or directory
    22 | #include <linux/tracepoint.h>
       |          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[4]: *** [usr/include/Makefile:85: usr/include/linux/pci.hdrtest] Error 1
make[3]: *** [scripts/Makefile.build:465: usr/include] Error 2
make[2]: *** [scripts/Makefile.build:465: usr] Error 2
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [/media/nvme/shawn.xs/kernels/linux/Makefile:1994: .] Error 2
make: *** [Makefile:251: __sub-make] Error 2

Do you have any objections that I reverted to this version v5?

Thanks.
Shuai