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From:   Igor Mammedov <imammedo@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     terraluna977@gmail.com, bhelgaas@google.com,
        linux-pci@vger.kernel.org, imammedo@redhat.com, mst@redhat.com
Subject: [PATCH] hack to debug acpiphp crash
Date:   Mon, 24 Jul 2023 15:59:02 +0200
Message-Id: <20230724135902.2217991-1-imammedo@redhat.com>
In-Reply-To: <11fc981c-af49-ce64-6b43-3e282728bd1a@gmail.com>
References: <11fc981c-af49-ce64-6b43-3e282728bd1a@gmail.com>
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Woody thanks for testing,

can you try following patch which will try to workaround NULL bus->self if it's
a really cuplrit and print an extra debug information.
Add following to kernel command line(make sure that CONFIG_DYNAMIC_DEBUG is enabled):

dyndbg="file drivers/pci/access.c +p; file drivers/pci/hotplug/acpiphp_glue.c +p; file drivers/pci/bus.c +p; file drivers/pci/pci.c +p; file drivers/pci/setup-bus.c +p" ignore_loglevel

What I find odd in you logs is that enable_slot() is called while native PCIe
should be used. Additional info might help to understand what's going on:
  1: 'lspci' output
  2:  DSDT and all SSDT ACPI tables (you can use 'acpidump -b' to get them).

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 drivers/pci/hotplug/acpiphp_glue.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 328d1e416014..9ce3fd9d72a9 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -485,7 +485,10 @@ static void enable_slot(struct acpiphp_slot *slot, bool bridge)
 	struct pci_bus *bus = slot->bus;
 	struct acpiphp_func *func;
 
+WARN(1, "enable_slot");
+pci_info(bus, "enable_slot bus\n");
 	if (bridge && bus->self && hotplug_is_native(bus->self)) {
+pr_err("enable_slot: bridge branch\n");
 		/*
 		 * If native hotplug is used, it will take care of hotplug
 		 * slot management and resource allocation for hotplug
@@ -498,8 +501,10 @@ static void enable_slot(struct acpiphp_slot *slot, bool bridge)
 				acpiphp_native_scan_bridge(dev);
 		}
 	} else {
+		LIST_HEAD(add_list);
 		int max, pass;
 
+pr_err("enable_slot: acpiphp_rescan_slot branch\n");
 		acpiphp_rescan_slot(slot);
 		max = acpiphp_max_busnr(bus);
 		for (pass = 0; pass < 2; pass++) {
@@ -508,13 +513,23 @@ static void enable_slot(struct acpiphp_slot *slot, bool bridge)
 					continue;
 
 				max = pci_scan_bridge(bus, dev, max, pass);
+pci_info(dev, "enable_slot: pci_scan_bridge: max: %d\n", max);
 				if (pass && dev->subordinate) {
 					check_hotplug_bridge(slot, dev);
 					pcibios_resource_survey_bus(dev->subordinate);
+                                        if (bus->self)
+						__pci_bus_size_bridges(dev->subordinate,
+								       &add_list);
 				}
 			}
 		}
-		pci_assign_unassigned_bridge_resources(bus->self);
+                if (bus->self) {
+pci_info(bus->self, "enable_slot: pci_assign_unassigned_bridge_resources:\n");
+			pci_assign_unassigned_bridge_resources(bus->self);
+                } else {
+pci_info(bus, "enable_slot: __pci_bus_assign_resources:\n");
+			__pci_bus_assign_resources(bus, &add_list, NULL);
+		}
 	}
 
 	acpiphp_sanitize_bus(bus);
@@ -541,6 +556,7 @@ static void enable_slot(struct acpiphp_slot *slot, bool bridge)
 		}
 		pci_dev_put(dev);
 	}
+pr_err("enable_slot: end\n");
 }
 
 /**
-- 
2.39.3