[PATCH v1] HID: hid-sensor-hub: Fix debug lock warning

[PATCH v1] HID: hid-sensor-hub: Fix debug lock warning

[Srinivas Pandruvada]

v1
Allocate mutex memory dynamically

v0
base version

Srinivas Pandruvada (1):
  HID: hid-sensor-hub: Fix debug lock warning

 drivers/hid/hid-sensor-hub.c   | 13 ++++++++++---
 include/linux/hid-sensor-hub.h |  4 ++--
 2 files changed, 12 insertions(+), 5 deletions(-)

-- 
2.1.0

[PATCH v1] HID: hid-sensor-hub: Fix debug lock warning

[Srinivas Pandruvada]

When CONFIG_DEBUG_LOCK_ALLOC is defined, mutex magic is compared and
warned for (l->magic != l), here l is the address of mutex pointer.
In hid-sensor-hub as part of hsdev creation, a per hsdev mutex is
initialized during MFD cell creation. This hsdev, which contains, mutex
is part of platform data for the a cell. But platform_data is copied
in platform_device_add_data() in platform.c. This copy will copy the
whole hsdev structure including mutex. But once copied the magic
will no longer match. So when client driver call
sensor_hub_input_attr_get_raw_value, this will trigger mutex warning.
So to avoid this allocate mutex dynamically. This will be same even
after copy.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 drivers/hid/hid-sensor-hub.c   | 13 ++++++++++---
 include/linux/hid-sensor-hub.h |  4 ++--
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/hid-sensor-hub.c b/drivers/hid/hid-sensor-hub.c
index 5eb338d..e3990f6 100644
--- a/drivers/hid/hid-sensor-hub.c
+++ b/drivers/hid/hid-sensor-hub.c
@@ -294,7 +294,7 @@ int sensor_hub_input_attr_get_raw_value(struct hid_sensor_hub_device *hsdev,
 	if (!report)
 		return -EINVAL;
 
-	mutex_lock(&hsdev->mutex);
+	mutex_lock(hsdev->mutex_ptr);
 	if (flag == SENSOR_HUB_SYNC) {
 		memset(&hsdev->pending, 0, sizeof(hsdev->pending));
 		init_completion(&hsdev->pending.ready);
@@ -328,7 +328,7 @@ int sensor_hub_input_attr_get_raw_value(struct hid_sensor_hub_device *hsdev,
 		kfree(hsdev->pending.raw_data);
 		hsdev->pending.status = false;
 	}
-	mutex_unlock(&hsdev->mutex);
+	mutex_unlock(hsdev->mutex_ptr);
 
 	return ret_val;
 }
@@ -667,7 +667,14 @@ static int sensor_hub_probe(struct hid_device *hdev,
 			hsdev->vendor_id = hdev->vendor;
 			hsdev->product_id = hdev->product;
 			hsdev->usage = collection->usage;
-			mutex_init(&hsdev->mutex);
+			hsdev->mutex_ptr = devm_kzalloc(&hdev->dev,
+							sizeof(struct mutex),
+							GFP_KERNEL);
+			if (!hsdev->mutex_ptr) {
+				ret = -ENOMEM;
+				goto err_stop_hw;
+			}
+			mutex_init(hsdev->mutex_ptr);
 			hsdev->start_collection_index = i;
 			if (last_hsdev)
 				last_hsdev->end_collection_index = i;
diff --git a/include/linux/hid-sensor-hub.h b/include/linux/hid-sensor-hub.h
index d48e91f..607b665 100644
--- a/include/linux/hid-sensor-hub.h
+++ b/include/linux/hid-sensor-hub.h
@@ -74,7 +74,7 @@ struct sensor_hub_pending {
  * @usage:		Usage id for this hub device instance.
  * @start_collection_index: Starting index for a phy type collection
  * @end_collection_index: Last index for a phy type collection
- * @mutex:		synchronizing mutex.
+ * @mutex_ptr:		synchronizing mutex pointer.
  * @pending:		Holds information of pending sync read request.
  */
 struct hid_sensor_hub_device {
@@ -84,7 +84,7 @@ struct hid_sensor_hub_device {
 	u32 usage;
 	int start_collection_index;
 	int end_collection_index;
-	struct mutex mutex;
+	struct mutex *mutex_ptr;
 	struct sensor_hub_pending pending;
 };
 
-- 
2.1.0

Re: [PATCH v1] HID: hid-sensor-hub: Fix debug lock warning

[Jiri Kosina]

On Thu, 7 May 2015, Srinivas Pandruvada wrote:

> When CONFIG_DEBUG_LOCK_ALLOC is defined, mutex magic is compared and
> warned for (l->magic != l), here l is the address of mutex pointer.
> In hid-sensor-hub as part of hsdev creation, a per hsdev mutex is
> initialized during MFD cell creation. This hsdev, which contains, mutex
> is part of platform data for the a cell. But platform_data is copied
> in platform_device_add_data() in platform.c. This copy will copy the
> whole hsdev structure including mutex. But once copied the magic
> will no longer match. So when client driver call
> sensor_hub_input_attr_get_raw_value, this will trigger mutex warning.
> So to avoid this allocate mutex dynamically. This will be same even
> after copy.
> 
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

Applied to for-4.1/upstream-fixes.

-- 
Jiri Kosina
SUSE Labs