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. Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx> Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx> --- v2: If power resource is already on, no need to check if device needs to be resumed. v1: By Lin Ming. drivers/acpi/power.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c index 215ecd0..3582a26 100644 --- a/drivers/acpi/power.c +++ b/drivers/acpi/power.c @@ -105,6 +105,7 @@ 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; @@ -223,7 +224,6 @@ 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); @@ -236,19 +236,14 @@ 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; } static int acpi_power_on(acpi_handle handle) { - int result = 0; + int result = 0, resume_device = 0; struct acpi_power_resource *resource = NULL; + struct acpi_power_resource_device *device_list; result = acpi_power_get_context(handle, &resource); if (result) @@ -264,10 +259,26 @@ static int acpi_power_on(acpi_handle handle) result = __acpi_power_on(resource); if (result) resource->ref_count--; + else + resume_device = 1; } mutex_unlock(&resource->resource_lock); + if (!resume_device) + return result; + + 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; } @@ -353,7 +364,7 @@ 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) { @@ -370,7 +381,7 @@ 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 */ @@ -412,10 +423,10 @@ 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; } @@ -719,6 +730,7 @@ 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); -- 1.7.12.21.g871e293 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html