Re: [PATCH] PCI: acpiphp: Log more slot and notification details

[Igor Mammedov <imammedo@redhat.com>]

On Tue,  8 Aug 2023 14:27:13 -0500
Bjorn Helgaas <helgaas@kernel.org> wrote:

> From: Bjorn Helgaas <bhelgaas@google.com>
> 
> When registering an acpiphp slot, log the slot name in the same style as
> pciehp and include the PCI bus/device and whether a device is present or
> the slot is empty.
> 
> When handling an ACPI notification, log the PCI bus/device and notification
> type.
> 
> Sample dmesg log diff:
> 
>     ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
>   - acpiphp: Slot [3] registered
>   - acpiphp: Slot [4] registered
>     PCI host bridge to bus 0000:00
>     pci 0000:00:03.0: [8086:100e] type 00 class 0x020000
>     <ACPI Device Check notification>

Having ACPI node name/path here that received notification would be helpfull  

>     pci 0000:00:04.0: [8086:100e] type 00 class 0x020000
> 
>     ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
>   + acpiphp: pci 0000:00:03 Slot(3) registered (enabled)
>   + acpiphp: pci 0000:00:04 Slot(4) registered (empty)
>     PCI host bridge to bus 0000:00
>     pci 0000:00:03.0: [8086:100e] type 00 class 0x020000
>     <ACPI Device Check notification>
>   + acpiphp: pci 0000:00:04 Slot(4) Device Check
>     pci 0000:00:04.0: [8086:100e] type 00 class 0x020000
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/hotplug/acpiphp_core.c |  4 ----
>  drivers/pci/hotplug/acpiphp_glue.c | 23 +++++++++++++++++++++--
>  2 files changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/acpiphp_core.c b/drivers/pci/hotplug/acpiphp_core.c
> index c02257f4b61c..19d47607d009 100644
> --- a/drivers/pci/hotplug/acpiphp_core.c
> +++ b/drivers/pci/hotplug/acpiphp_core.c
> @@ -282,8 +282,6 @@ int acpiphp_register_hotplug_slot(struct acpiphp_slot *acpiphp_slot,
>  		goto error_slot;
>  	}
>  
> -	pr_info("Slot [%s] registered\n", slot_name(slot));
> -
>  	return 0;
>  error_slot:
>  	kfree(slot);
> @@ -296,8 +294,6 @@ void acpiphp_unregister_hotplug_slot(struct acpiphp_slot *acpiphp_slot)
>  {
>  	struct slot *slot = acpiphp_slot->slot;
>  
> -	pr_info("Slot [%s] unregistered\n", slot_name(slot));
> -
>  	pci_hp_deregister(&slot->hotplug_slot);
>  	kfree(slot);
>  }
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index 328d1e416014..eeca2753a5c7 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -25,7 +25,7 @@
>   *    bus. It loses the refcount when the driver unloads.
>   */
>  
> -#define pr_fmt(fmt) "acpiphp_glue: " fmt
> +#define pr_fmt(fmt) "acpiphp: " fmt
>  
>  #include <linux/module.h>
>  
> @@ -333,6 +333,12 @@ static acpi_status acpiphp_add_context(acpi_handle handle, u32 lvl, void *data,
>  				       &val, 60*1000))
>  		slot->flags |= SLOT_ENABLED;
>  
> +	if (slot->slot)
> +		pr_info("pci %04x:%02x:%02x Slot(%s) registered (%s)\n",
> +			pci_domain_nr(slot->bus), slot->bus->number,
> +			slot->device, slot_name(slot->slot),
> +			slot->flags & SLOT_ENABLED ? "enabled" : "empty");
> +
>  	return AE_OK;
>  }
>  
> @@ -351,8 +357,13 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
>  			acpi_unlock_hp_context();
>  		}
>  		slot->flags |= SLOT_IS_GOING_AWAY;
> -		if (slot->slot)
> +		if (slot->slot) {
> +			pr_info("pci %04x:%02x:%02x Slot(%s) unregistered\n",
> +				pci_domain_nr(slot->bus), slot->bus->number,
> +				slot->device, slot_name(slot->slot));
> +
>  			acpiphp_unregister_hotplug_slot(slot);
> +		}
>  	}
>  
>  	mutex_lock(&bridge_mutex);
> @@ -793,6 +804,14 @@ static void hotplug_event(u32 type, struct acpiphp_context *context)
>  
>  	pci_lock_rescan_remove();
>  
> +	pr_info("pci %04x:%02x:%02x Slot(%s) %s\n",
> +		pci_domain_nr(slot->bus), slot->bus->number,
> +		slot->device, slot_name(slot->slot),
I had similar issue with logging patches that I've asked Woody to run.

it crashes here with buscheck on non existing device

Call Trace:
 <TASK>
 ? __die_body+0x19/0x60
 ? page_fault_oops+0x158/0x430
 ? fixup_exception+0x21/0x330
 ? exc_page_fault+0x6b/0x150
 ? asm_exc_page_fault+0x26/0x30
 ? acpiphp_hotplug_notify+0x13d/0x2f0
 ? __pfx_acpiphp_hotplug_notify+0x10/0x10
 acpi_device_hotplug+0xc2/0x4f0
 acpi_hotplug_work_fn+0x19/0x30
 process_one_work+0x1f8/0x3e0
 worker_thread+0x29/0x3b0
 ? __pfx_worker_thread+0x10/0x10
 kthread+0xf2/0x120
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x2f/0x40
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0

(gdb) p *slot
$2 = {node = {next = 0xffff8881003287c0, prev = 0xffff888100887730}, bus = 0xffff8881003de800,
 funcs = {next = 0xffff8881008877b0, prev = 0xffff888100887a50}, slot = 0x0 <fixed_percpu_data>,
                                                                 ^^^ likely culprit
 device = 0x0, flags = 0x1}


reproducer hack: https://gitlab.com/imammedo/qemu/-/tree/acpiphp_buscheck_on_missing_device?ref_type=heads

 ./qemu-system-x86_64 -M q35 -cpu host -smp 4 -enable-kvm  -m 6G  -kernel ~/builds/linux-2.6/arch/x86/boot/bzImage -append 'nokaslr root=/dev/sda1 console=ttyS0' -snapshot rhel9.img  -device pcie-root-port,id=rp1,bus=pcie.0,chassis=0,addr=8 -monitor stdio -serial file:/tmp/s -s

then once booted to trigger buscheck issue at monitor prompt:
(qemu) device_add e1000e,bus=rp1

> +		type == ACPI_NOTIFY_BUS_CHECK ? "Bus Check" :
> +		type == ACPI_NOTIFY_DEVICE_CHECK ? "Device Check" :
> +		type == ACPI_NOTIFY_EJECT_REQUEST ? "Eject Request" :
> +		"Notification");
> +
>  	switch (type) {
>  	case ACPI_NOTIFY_BUS_CHECK:
>  		/* bus re-enumerate */