[PATCH 2/3] ACPI: Get acpi_device's parent from the parent field

Sakari Ailus
2021-11-03T13:33:52Z

Printk modifier %pfw is used to print the full path of the device name.
This is obtained device by device until a device no longer has a parent.

On ACPI getting the parent fwnode is done by calling acpi_get_parent()
which tries to down() a semaphore. But local IRQs are now disabled in
vprintk_store() before the mutex is acquired. This is obviously a problem.

Luckily struct acpi_device has a parent field already. Use that field to
get the parent instead of relying on acpi_get_parent().

Fixes: 002eb6ad0751 ("printk: track/limit recursion")
Cc: stable@vger.kernel.org # v5.15 and up
Depends-on: ("ACPI: Make acpi_fwnode_handle safer")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
drivers/acpi/property.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index e312ebaed8db4..7403ee2816eb8 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -1089,16 +1089,12 @@ struct fwnode_handle *acpi_node_get_parent(const struct fwnode_handle *fwnode)
if (is_acpi_data_node(fwnode)) {
/* All data nodes have parent pointer so just return that */
return to_acpi_data_node(fwnode)->parent;
- } else if (is_acpi_device_node(fwnode)) {
- acpi_handle handle, parent_handle;
+ }

- handle = to_acpi_device_node(fwnode)->handle;
- if (ACPI_SUCCESS(acpi_get_parent(handle, &parent_handle))) {
- struct acpi_device *adev;
+ if (is_acpi_device_node(fwnode)) {
+ struct acpi_device *device = to_acpi_device_node(fwnode);

- if (!acpi_bus_get_device(parent_handle, &adev))
- return acpi_fwnode_handle(adev);
- }
+ return acpi_fwnode_handle(device->parent);
}

return NULL;
--
2.30.2