On Mon, Jun 25, 2012 at 1:09 PM, Lin Ming <ming.m.lin@xxxxxxxxx> wrote:
> Commit 0090def("ACPI: Add interface to register/unregister device
> to/from power resources") used resource_lock to protect the devices list
> that relies on power resource. It caused a mutex dead lock, as below
>
> acpi_power_on ---> lock resource_lock
> __acpi_power_on
> acpi_power_on_device
> acpi_power_get_inferred_state
> acpi_power_get_list_state ---> lock resource_lock
>
> This patch adds a new mutex "devices_lock" to protect the devices list
> and calls acpi_power_on_device in acpi_power_on, instead of
> __acpi_power_on, after the resource_lock is released.
Len,
What do you think of this fix?
Regards,
Lin Ming
>
> Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
> ---
> drivers/acpi/power.c | 29 ++++++++++++++++++-----------
> 1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
> index eb640874..068349e 100644
> --- a/drivers/acpi/power.c
> +++ b/drivers/acpi/power.c
> @@ -103,6 +103,7 @@ struct acpi_power_resource {
>
> /* List of devices relying on this power resource */
> struct acpi_power_resource_device *devices;
> + struct mutex devices_lock;
> };
>
> static struct list_head acpi_power_resource_list;
> @@ -221,7 +222,6 @@ static void acpi_power_on_device(struct acpi_power_managed_device *device)
>
> static int __acpi_power_on(struct acpi_power_resource *resource)
> {
> - struct acpi_power_resource_device *device_list = resource->devices;
> acpi_status status = AE_OK;
>
> status = acpi_evaluate_object(resource->device->handle, "_ON", NULL, NULL);
> @@ -234,12 +234,6 @@ static int __acpi_power_on(struct acpi_power_resource *resource)
> ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Power resource [%s] turned on\n",
> resource->name));
>
> - while (device_list) {
> - acpi_power_on_device(device_list->device);
> -
> - device_list = device_list->next;
> - }
> -
> return 0;
> }
>
> @@ -247,6 +241,7 @@ static int acpi_power_on(acpi_handle handle)
> {
> int result = 0;
> struct acpi_power_resource *resource = NULL;
> + struct acpi_power_resource_device *device_list;
>
> result = acpi_power_get_context(handle, &resource);
> if (result)
> @@ -266,6 +261,17 @@ static int acpi_power_on(acpi_handle handle)
>
> mutex_unlock(&resource->resource_lock);
>
> + mutex_lock(&resource->devices_lock);
> +
> + device_list = resource->devices;
> + while (device_list) {
> + acpi_power_on_device(device_list->device);
> +
> + device_list = device_list->next;
> + }
> +
> + mutex_unlock(&resource->devices_lock);
> +
> return result;
> }
>
> @@ -351,7 +357,7 @@ static void __acpi_power_resource_unregister_device(struct device *dev,
> if (acpi_power_get_context(res_handle, &resource))
> return;
>
> - mutex_lock(&resource->resource_lock);
> + mutex_lock(&resource->devices_lock);
> prev = NULL;
> curr = resource->devices;
> while (curr) {
> @@ -368,7 +374,7 @@ static void __acpi_power_resource_unregister_device(struct device *dev,
> prev = curr;
> curr = curr->next;
> }
> - mutex_unlock(&resource->resource_lock);
> + mutex_unlock(&resource->devices_lock);
> }
>
> /* Unlink dev from all power resources in _PR0 */
> @@ -410,10 +416,10 @@ static int __acpi_power_resource_register_device(
>
> power_resource_device->device = powered_device;
>
> - mutex_lock(&resource->resource_lock);
> + mutex_lock(&resource->devices_lock);
> power_resource_device->next = resource->devices;
> resource->devices = power_resource_device;
> - mutex_unlock(&resource->resource_lock);
> + mutex_unlock(&resource->devices_lock);
>
> return 0;
> }
> @@ -717,6 +723,7 @@ static int acpi_power_add(struct acpi_device *device)
>
> resource->device = device;
> mutex_init(&resource->resource_lock);
> + mutex_init(&resource->devices_lock);
> strcpy(resource->name, device->pnp.bus_id);
> strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
> strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
> --
> 1.7.10
>
>
>
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