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

[Shuai Xue]

在 2025/1/15 10:41, Steven Rostedt 写道:
> On Wed, 15 Jan 2025 09:37:53 +0800
> Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx> 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