linux-kernel - Re: [PATCH v6] PCI: hotplug: Add a generic RAS tracepoint for hotplug event

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Message-ID: <7b482de1-fa19-45d6-bd05-f1c3ebb77192@linux.alibaba.com>
Date: Wed, 15 Jan 2025 11:59:13 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: Steven Rostedt <rostedt@...dmis.org>, Lukas Wunner <lukas@...ner.de>
Cc: 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 v6] PCI: hotplug: Add a generic RAS tracepoint for hotplug
 event



在 2025/1/15 10:41, Steven Rostedt 写道:
> On Wed, 15 Jan 2025 09:37:53 +0800
> Shuai Xue <xueshuai@...ux.alibaba.com> wrote:
> 
>> +#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);
> 
> Hmm, can't you just pass in the ctrl pointer to the tracepoint?
> 
> 			trace_pci_hp_event(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..1415ac505cb5
>> --- /dev/null
>> +++ b/drivers/pci/hotplug/trace.h
>> @@ -0,0 +1,45 @@
>> +/* 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
>> +
>> +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	)
> 
> Then the above would be:
> 
> 	TP_PROTO(struct controller *ctrl, int event),
> 
> // don't really need a const int there
> 
> 	TP_ARGS(ctrl, event),
> 
> 	TP_STRUCT__entry(
> 		__string(	port_name,	pci_name(ctrl->pcie->port)	)
> 		__string(	slot,		slot_name(ctrl)			)
> 		__field(	int,		event				)
> 
> and everything else could be the same.

Maybe it's not a good idea.

I think pci_hp_event is a generic event for pciehp, shpchp, octep_hp, etc. But
each hotplug driver has different `struct controller` and slot_name(). For
example:

// drivers/pci/hotplug/pciehp.h
static inline const char *slot_name(struct controller *ctrl)
{
	return hotplug_slot_name(&ctrl->hotplug_slot);
}

// drivers/pci/hotplug/shpchp.h
static inline const char *slot_name(struct slot *slot)
{
	return hotplug_slot_name(&slot->hotplug_slot);
}

So, IMHO, pass port_name and slot_name from each driver is more simple.

+ @Lukas for hotplug part.

> 
> -- Steve
> 
> 

Thanks.

Best Regards,
Shuai