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 <achiang@hp.com>
Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 648596d..91156f8 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -700,9 +700,10 @@
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 @@
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)