Hi,
On 6/16/21 8:00 PM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> If acpi_add_single_object() runs concurrently with respect to
> acpi_scan_clear_dep() which deletes a dependencies list entry where
> the device being added is the consumer, the device's dep_unmet
> counter may not be updated to reflect that change.
>
> Namely, if the dependencies list entry is deleted right after
> calling acpi_scan_dep_init() and before calling acpi_device_add(),
> acpi_scan_clear_dep() will not find the device object corresponding
> to the consumer device ACPI handle and it will not update its
> dep_unmet counter to reflect the deletion of the list entry.
> Consequently, the dep_unmet counter of the device will never
> become zero going forward which may prevent it from being
> completely enumerated.
>
> To address this problem, modify acpi_add_single_object() to run
> acpi_tie_acpi_dev(), to attach the ACPI device object created by it
> to the corresponding ACPI namespace node, under acpi_dep_list_lock
> along with acpi_scan_dep_init() whenever the latter is called.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
FWIW this looks good to me now.
Regards,
Hans
> ---
>
> -> v2:
> * Fix memory leak spotted by Hans.
> * Add the R-by tag from Hans.
>
> ---
> drivers/acpi/scan.c | 50 ++++++++++++++++++++++++++++++++------------------
> 1 file changed, 32 insertions(+), 18 deletions(-)
>
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -657,16 +652,12 @@ static int acpi_tie_acpi_dev(struct acpi
> return 0;
> }
>
> -int acpi_device_add(struct acpi_device *device,
> - void (*release)(struct device *))
> +int __acpi_device_add(struct acpi_device *device,
> + void (*release)(struct device *))
> {
> struct acpi_device_bus_id *acpi_device_bus_id;
> int result;
>
> - result = acpi_tie_acpi_dev(device);
> - if (result)
> - return result;
> -
> /*
> * Linkage
> * -------
> @@ -755,6 +746,17 @@ err_unlock:
> return result;
> }
>
> +int acpi_device_add(struct acpi_device *adev, void (*release)(struct device *))
> +{
> + int ret;
> +
> + ret = acpi_tie_acpi_dev(adev);
> + if (ret)
> + return ret;
> +
> + return __acpi_device_add(adev, release);
> +}
> +
> /* --------------------------------------------------------------------------
> Device Enumeration
> -------------------------------------------------------------------------- */
> @@ -1681,14 +1683,10 @@ static void acpi_scan_dep_init(struct ac
> {
> struct acpi_dep_data *dep;
>
> - mutex_lock(&acpi_dep_list_lock);
> -
> list_for_each_entry(dep, &acpi_dep_list, node) {
> if (dep->consumer == adev->handle)
> adev->dep_unmet++;
> }
> -
> - mutex_unlock(&acpi_dep_list_lock);
> }
>
> void acpi_device_add_finalize(struct acpi_device *device)
> @@ -1707,6 +1705,7 @@ static int acpi_add_single_object(struct
> acpi_handle handle, int type, bool dep_init)
> {
> struct acpi_device *device;
> + bool release_dep_lock = false;
> int result;
>
> device = kzalloc(sizeof(struct acpi_device), GFP_KERNEL);
> @@ -1720,16 +1719,31 @@ static int acpi_add_single_object(struct
> * this must be done before the get power-/wakeup_dev-flags calls.
> */
> if (type == ACPI_BUS_TYPE_DEVICE || type == ACPI_BUS_TYPE_PROCESSOR) {
> - if (dep_init)
> + if (dep_init) {
> + mutex_lock(&acpi_dep_list_lock);
> + /*
> + * Hold the lock until the acpi_tie_acpi_dev() call
> + * below to prevent concurrent acpi_scan_clear_dep()
> + * from deleting a dependency list entry without
> + * updating dep_unmet for the device.
> + */
> + release_dep_lock = true;
> acpi_scan_dep_init(device);
> -
> + }
> acpi_scan_init_status(device);
> }
>
> acpi_bus_get_power_flags(device);
> acpi_bus_get_wakeup_device_flags(device);
>
> - result = acpi_device_add(device, acpi_device_release);
> + result = acpi_tie_acpi_dev(device);
> +
> + if (release_dep_lock)
> + mutex_unlock(&acpi_dep_list_lock);
> +
> + if (!result)
> + result = __acpi_device_add(device, acpi_device_release);
> +
> if (result) {
> acpi_device_release(&device->dev);
> return result;
>
>
>
