[PATCH v2 2/13] ACPI / hotplug / PCI: Move PCI rescan-remove locking to hotplug_event()

From: Rafael J. Wysocki
Date: Sat Feb 01 2014 - 19:18:36 EST

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Commit 9217a984671e (ACPI / hotplug / PCI: Use global PCI rescan-remove
locking) modified ACPIPHP to protect its PCI device removal and addition
code paths from races against sysfs-driven rescan and remove operations
with the help of PCI rescan-remove locking. However, it overlooked the
fact that hotplug_event_work() is not the only caller of hotplug_event()
which may also be called by dock_hotplug_event() and that code path
is missing the PCI rescan-remove locking. This means that, although
the PCI rescan-remove lock is held as appropriate during the handling
of events originating from handle_hotplug_event(), the ACPIPHP's
operations resulting from dock events may still suffer the race
conditions that commit 9217a984671e was supposed to eliminate.

To address that problem, move the PCI rescan-remove locking from
hotplug_event_work() to hotplug_event() so that it is used regardless
of the way that function is invoked.

Revamps: 9217a984671e (ACPI / hotplug / PCI: Use global PCI rescan-remove locking)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
drivers/pci/hotplug/acpiphp_glue.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c
--- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c
+++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c
@@ -852,6 +852,7 @@ static void hotplug_event(acpi_handle ha


+ pci_lock_rescan_remove();
acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);

switch (type) {
@@ -905,6 +906,7 @@ static void hotplug_event(acpi_handle ha

+ pci_unlock_rescan_remove();
if (bridge)
@@ -915,11 +917,9 @@ static void hotplug_event_work(void *dat
acpi_handle handle = context->handle;

- pci_lock_rescan_remove();

hotplug_event(handle, type, context);

- pci_unlock_rescan_remove();
acpi_evaluate_hotplug_ost(handle, type, ACPI_OST_SC_SUCCESS, NULL);

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