Re: [PATCH v8] PCI: hotplug: Add a generic RAS tracepoint for hotplug event

[Shuai Xue <xueshuai@linux.alibaba.com>]

在 2025/6/2 14:30, Ilpo Järvinen 写道:
> On Mon, 12 May 2025, Shuai Xue wrote:
> 
>> 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>
>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>> Reviewed-by: Lukas Wunner <lukas@wunner.de>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> ---
>> changes since v7:
>> - replace the TRACE_INCLUDE_PATH to avoid macro conflict per Steven
>> - pick up Reviewed-by from Lukas Wunner
>> ---
>>   drivers/pci/hotplug/Makefile      |  3 ++
>>   drivers/pci/hotplug/pciehp_ctrl.c | 33 ++++++++++++---
>>   drivers/pci/hotplug/trace.h       | 68 +++++++++++++++++++++++++++++++
>>   include/uapi/linux/pci.h          |  7 ++++
>>   4 files changed, 105 insertions(+), 6 deletions(-)
>>   create mode 100644 drivers/pci/hotplug/trace.h
>>
>> diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
>> index 40aaf31fe338..a1a9d1e98962 100644
>> --- a/drivers/pci/hotplug/Makefile
>> +++ b/drivers/pci/hotplug/Makefile
>> @@ -3,6 +3,9 @@
>>   # Makefile for the Linux kernel pci hotplug controller drivers.
>>   #
>>   
>> +# define_trace.h needs to know how to find our header
>> +CFLAGS_pciehp_ctrl.o				:= -I$(src)
>> +
>>   obj-$(CONFIG_HOTPLUG_PCI)		+= pci_hotplug.o
>>   obj-$(CONFIG_HOTPLUG_PCI_COMPAQ)	+= cpqphp.o
>>   obj-$(CONFIG_HOTPLUG_PCI_IBM)		+= ibmphp.o
>> 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"
> 
> Hi,
> 
> Instead of spreading tracepoint creating into subdriver code like this,
> should we place it into one place, e.g., drivers/pci/pci-trace.c (which is
> what I seem to have used in my yet to be submitted patch that adds
> tracepoints into bwctrl link speed events)?
> 
>> diff --git a/drivers/pci/hotplug/trace.h b/drivers/pci/hotplug/trace.h
>> new file mode 100644
>> index 000000000000..21329c198019
>> --- /dev/null
>> +++ b/drivers/pci/hotplug/trace.h
> 
> Perhaps in include/trace/events/pci.h (or
> include/trace/events/pci-hotplug.h)?
> 
> I don't know what is the general rule having them inside drivers/ vs
> include/trace/events, Documentation/trace/tracepoints.rst only mentions
> the latter, but there seems to be plenty under drivers/ too.
> 

Hi, Ilpo,

I don't know either.

I think it is tracepoint stuff and it is up to @Steve.
@Steve, which way do you prefer?

Thanks for help.

Best Regards,
Shuai