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Subject[ 060/218] ACPI / PM: Fix resource_lock dead lock in acpi_power_on_device
Date
3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lin Ming <ming.m.lin@intel.com>

commit 40bf66ec9791f1452b90b82aadc3b6e6aee201f5 upstream.

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 <ming.m.lin@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/acpi/power.c | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)

--- 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

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);
@@ -234,19 +234,15 @@ static int __acpi_power_on(struct acpi_p
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)
@@ -262,10 +258,25 @@ static int acpi_power_on(acpi_handle han
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;
}

@@ -351,7 +362,7 @@ static void __acpi_power_resource_unregi
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 +379,7 @@ static void __acpi_power_resource_unregi
prev = curr;
curr = curr->next;
}
- mutex_unlock(&resource->resource_lock);
+ mutex_unlock(&resource->devices_lock);
}

/* Unlink dev from all power resources in _PR0 */
@@ -409,10 +420,10 @@ static int __acpi_power_resource_registe

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;
}
@@ -715,6 +726,7 @@ static int acpi_power_add(struct acpi_de

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);



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