linux-kernel - [PATCH] HID: Replace semaphore driver

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Date:   Thu,  8 Jun 2017 15:31:56 +0530
From:   Binoy Jayan <binoy.jayan@...aro.org>
To:     Binoy Jayan <binoy.jayan@...aro.org>
Cc:     linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Rajendra <rnayak@...eaurora.org>,
        Mark Brown <broonie@...nel.org>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: [PATCH] HID: Replace semaphore driver_lock with mutex

The semaphore 'driver_lock' is used as a simple mutex, so
it should be written as one. Semaphores are going away in the future.

Signed-off-by: Binoy Jayan <binoy.jayan@...aro.org>
---

This patch is part of a bigger effort to eliminate unwanted
semaphores from the linux kernel.

 drivers/hid/hid-core.c | 10 +++++-----
 include/linux/hid.h    |  2 +-
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 37084b6..bf21dac 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2222,7 +2222,7 @@ static int hid_device_probe(struct device *dev)
 	const struct hid_device_id *id;
 	int ret = 0;
 
-	if (down_interruptible(&hdev->driver_lock))
+	if (mutex_lock_interruptible(&hdev->driver_lock))
 		return -EINTR;
 	if (down_interruptible(&hdev->driver_input_lock)) {
 		ret = -EINTR;
@@ -2254,7 +2254,7 @@ static int hid_device_probe(struct device *dev)
 	if (!hdev->io_started)
 		up(&hdev->driver_input_lock);
 unlock_driver_lock:
-	up(&hdev->driver_lock);
+	mutex_unlock(&hdev->driver_lock);
 	return ret;
 }
 
@@ -2264,7 +2264,7 @@ static int hid_device_remove(struct device *dev)
 	struct hid_driver *hdrv;
 	int ret = 0;
 
-	if (down_interruptible(&hdev->driver_lock))
+	if (mutex_lock_interruptible(&hdev->driver_lock))
 		return -EINTR;
 	if (down_interruptible(&hdev->driver_input_lock)) {
 		ret = -EINTR;
@@ -2285,7 +2285,7 @@ static int hid_device_remove(struct device *dev)
 	if (!hdev->io_started)
 		up(&hdev->driver_input_lock);
 unlock_driver_lock:
-	up(&hdev->driver_lock);
+	mutex_unlock(&hdev->driver_lock);
 	return ret;
 }
 
@@ -2742,7 +2742,7 @@ 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);
+	mutex_init(&hdev->driver_lock);
 	sema_init(&hdev->driver_input_lock, 1);
 
 	return hdev;
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 5be325d..1add2b3 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -516,7 +516,7 @@ 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 mutex 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;
-- 
Binoy Jayan