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

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Message-ID: <20250114214103.6b45d30d@gandalf.local.home>
Date: Tue, 14 Jan 2025 21:41:03 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Shuai Xue <xueshuai@...ux.alibaba.com>
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 v6] PCI: hotplug: Add a generic RAS tracepoint for
 hotplug event

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.

-- 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)
> +	)
> +);