ACPI / hotplug / PCI: Execute _EJ0 under the ACPI scan lock

Since acpi_device_hotplug() assumes that ACPI handles of device
objects passed to it will not become invalid while acpi_scan_lock
is being held, make acpiphp_disable_slot() acquire acpi_scan_lock,
because it generally causes _EJ0 to be executed for one of the
devices in the slot and that may cause its ACPI handle to become
invalid.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 11a6117fb358..fa8fe7441952 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -1007,9 +1007,15 @@ int acpiphp_disable_slot(struct acpiphp_slot *slot)
 {
         int ret;
 
+        /*
+         * Acquire acpi_scan_lock to ensure that the execution of _EJ0 in
+         * acpiphp_disable_and_eject_slot() will be synchronized properly.
+         */
+        acpi_scan_lock_acquire();
         pci_lock_rescan_remove();
         ret = acpiphp_disable_and_eject_slot(slot);
         pci_unlock_rescan_remove();
+        acpi_scan_lock_release();
         return ret;
 }