Commit 2682b892 authored by Jiri Kosina's avatar Jiri Kosina
Browse files

Merge branch 'for-4.14/driver-lock-removal' into for-linus 

- Arnd pointed out that driver_lock semaphore is superfluous, as
  driver core already provides all the necessary concurency protection.
  Removal patch from Binoy Jayan
parents aaf4f13c 6f68f0ac

drivers/hid/hid-core.c

+4 −11
Original line number Diff line number Diff line
@@ -2488,11 +2488,9 @@ static int hid_device_probe(struct device *dev) 
	const struct hid_device_id *id;

	int ret = 0;



	if (down_interruptible(&hdev->driver_lock))

		return -EINTR;

	if (down_interruptible(&hdev->driver_input_lock)) {

		ret = -EINTR;

		goto unlock_driver_lock;

		goto end;

	}

	hdev->io_started = false;
@@ -2519,8 +2517,7 @@ static int hid_device_probe(struct device *dev) 
unlock:

	if (!hdev->io_started)

		up(&hdev->driver_input_lock);

unlock_driver_lock:

	up(&hdev->driver_lock);

end:

	return ret;

}
@@ -2530,11 +2527,9 @@ static int hid_device_remove(struct device *dev) 
	struct hid_driver *hdrv;

	int ret = 0;



	if (down_interruptible(&hdev->driver_lock))

		return -EINTR;

	if (down_interruptible(&hdev->driver_input_lock)) {

		ret = -EINTR;

		goto unlock_driver_lock;

		goto end;

	}

	hdev->io_started = false;
@@ -2550,8 +2545,7 @@ static int hid_device_remove(struct device *dev) 


	if (!hdev->io_started)

		up(&hdev->driver_input_lock);

unlock_driver_lock:

	up(&hdev->driver_lock);

end:

	return ret;

}
@@ -3009,7 +3003,6 @@ struct hid_device *hid_allocate_device(void) 
	init_waitqueue_head(&hdev->debug_wait);

	INIT_LIST_HEAD(&hdev->debug_list);

	spin_lock_init(&hdev->debug_list_lock);

	sema_init(&hdev->driver_lock, 1);

	sema_init(&hdev->driver_input_lock, 1);

	mutex_init(&hdev->ll_open_lock);

include/linux/hid.h

+1 −2
Original line number Diff line number Diff line
@@ -526,7 +526,6 @@ struct hid_device { /* device report descriptor */ 
	struct hid_report_enum report_enum[HID_REPORT_TYPES];

	struct work_struct led_work;					/* delayed LED worker */



	struct semaphore driver_lock;					/* protects the current driver, except during input */

	struct semaphore driver_input_lock;				/* protects the current driver */

	struct device dev;						/* device */

	struct hid_driver *driver;
@@ -553,7 +552,7 @@ struct hid_device { /* device report descriptor */ 
	unsigned int status;						/* see STAT flags above */

	unsigned claimed;						/* Claimed by hidinput, hiddev? */

	unsigned quirks;						/* Various quirks the device can pull on us */

	bool io_started;						/* Protected by driver_lock. If IO has started */

	bool io_started;						/* If IO has started */



	struct list_head inputs;					/* The list of inputs */

	void *hiddev;							/* The hiddev structure */