From a13307cef8bf51990ef1d525b1cbdcc2cfe07e2a Mon Sep 17 00:00:00 2001 From: Alex Chiang Date: Tue, 1 Jul 2008 20:02:23 -0600 Subject: [PATCH] PCI: acpiphp: cleanup notify handler on all root bridges During the development of the physical PCI slot patch series, Gary Hade kept on reporting strange oopses due to interactions between pci_slot and acpiphp. http://lkml.org/lkml/2007/11/28/319 find_root_bridges() unconditionally installs handle_hotplug_event_bridge() as an ACPI_SYSTEM_NOTIFY handler for all root bridges. However, during module cleanup, remove_bridge() will only remove the notify handler iff the root bridge had a hot-pluggable slot directly underneath. That is: root bridge -> hotplug slot But, if the topology looks like either of the following: root bridge -> non-hotplug slot root bridge -> p2p bridge -> hotplug slot Then we currently do not remove the notify handler from that root bridge. This can cause a kernel oops if we modprobe acpiphp later and it gets loaded somewhere else in memory. If the root bridge then receives a hotplug event, it will then attempt to call a stale, non-existent notify handler and we blow up. Much thanks goes to Gary Hade for his persistent debugging efforts. Signed-off-by: Alex Chiang Signed-off-by: Gary Hade Signed-off-by: Jesse Barnes --- drivers/pci/hotplug/acpiphp_glue.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 648596d469f6..91156f85a926 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -700,9 +700,10 @@ cleanup_p2p_bridge(acpi_handle handle, u32 lvl, void *context, void **rv) acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1, cleanup_p2p_bridge, NULL, NULL); - if (!(bridge = acpiphp_handle_to_bridge(handle))) - return AE_OK; - cleanup_bridge(bridge); + bridge = acpiphp_handle_to_bridge(handle); + if (bridge) + cleanup_bridge(bridge); + return AE_OK; } @@ -715,9 +716,19 @@ static void remove_bridge(acpi_handle handle) acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1, cleanup_p2p_bridge, NULL, NULL); + /* + * On root bridges with hotplug slots directly underneath (ie, + * no p2p bridge inbetween), we call cleanup_bridge(). + * + * The else clause cleans up root bridges that either had no + * hotplug slots at all, or had a p2p bridge underneath. + */ bridge = acpiphp_handle_to_bridge(handle); if (bridge) cleanup_bridge(bridge); + else + acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY, + handle_hotplug_event_bridge); } static struct pci_dev * get_apic_pci_info(acpi_handle handle) -- 2.20.1