[PATCH 1/1] ACPI: scan: Fix Battery devices sometimes never binding

[Hans de Goede <hdegoede@redhat.com>]

With the new 2 step scanning process, which defers instantiating some
ACPI-devices based on their _DEP to the second step, the following may
happen:

1. During the first acpi_walk_namespace(acpi_bus_check_add) call
   acpi_scan_check_dep() gets called on the Battery ACPI dev handle and
   adds one or more deps for this handle to the acpi_dep_list

2. During the first acpi_bus_attach() call one or more of the suppliers of
   these deps get their driver attached and
   acpi_walk_dep_device_list(supplier_handle) gets called.

   At this point acpi_bus_get_device(dep->consumer) get called,
   but since the battery has DEPs it has not been instantiated during the
   first acpi_walk_namespace(acpi_bus_check_add), so the
   acpi_bus_get_device(dep->consumer) call fails.

   Before this commit, acpi_walk_dep_device_list() would now continue
   *without* removing the acpi_dep_data entry for this supplier,consumer
   pair from the acpi_dep_list.

3. During the second acpi_walk_namespace(acpi_bus_check_add) call
   an acpi_device gets instantiated for the battery and
   acpi_scan_dep_init() gets called to initialize its dep_unmet val.

   Before this commit, the dep_unmet count would include DEPs for
   suppliers for which acpi_walk_dep_device_list(supplier_handle)
   has already been called, so it will never become 0 and the
   ACPI battery driver will never get attached / bind.

Fix the ACPI battery driver never binding in this scenario by making
acpi_walk_dep_device_list() always remove matching acpi_dep_data
entries independent of the acpi_bus_get_device(dep->consumer) call
succeeding or not.

Fixes: 71da201f38df ("ACPI: scan: Defer enumeration of devices with _DEP lists")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/acpi/scan.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 5d7b2fcecf06..4ce54115e981 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2123,12 +2123,12 @@ void acpi_walk_dep_device_list(acpi_handle handle)
 	list_for_each_entry_safe(dep, tmp, &acpi_dep_list, node) {
 		if (dep->supplier == handle) {
 			acpi_bus_get_device(dep->consumer, &adev);
-			if (!adev)
-				continue;
 
-			adev->dep_unmet--;
-			if (!adev->dep_unmet)
-				acpi_bus_attach(adev, true);
+			if (adev) {
+				adev->dep_unmet--;
+				if (!adev->dep_unmet)
+					acpi_bus_attach(adev, true);
+			}
 
 			list_del(&dep->node);
 			kfree(dep);
-- 
2.29.2