From 40bf66ec9791f1452b90b82aadc3b6e6aee201f5 Mon Sep 17 00:00:00 2001 From: Lin Ming Date: Fri, 14 Sep 2012 00:26:33 +0200 Subject: [PATCH] ACPI / PM: Fix resource_lock dead lock in acpi_power_on_device 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. [rjw: Changed data type of a boolean variable to bool.] Signed-off-by: Lin Ming Signed-off-by: Aaron Lu Cc: stable@vger.kernel.org Signed-off-by: Rafael J. Wysocki --- drivers/acpi/power.c | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c index fc1803414629..cc2a2dcff336 100644 --- a/drivers/acpi/power.c +++ b/drivers/acpi/power.c @@ -107,6 +107,7 @@ 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; @@ -225,7 +226,6 @@ 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); @@ -238,19 +238,15 @@ 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; + bool resume_device = false; struct acpi_power_resource *resource = NULL; + struct acpi_power_resource_device *device_list; result = acpi_power_get_context(handle, &resource); if (result) @@ -266,10 +262,25 @@ static int acpi_power_on(acpi_handle handle) result = __acpi_power_on(resource); if (result) resource->ref_count--; + else + resume_device = true; } 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; } @@ -355,7 +366,7 @@ 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) { @@ -372,7 +383,7 @@ 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 */ @@ -414,10 +425,10 @@ 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; } @@ -721,6 +732,7 @@ 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); -- 2.20.1