HID: Remove the semaphore driver_lock

The semaphore 'driver_lock' is used as a simple mutex, and also unnecessary as
suggested by Arnd. Hence removing it, as the concurrency between the probe and
remove is already handled in the driver core.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Binoy Jayan <binoy.jayan@linaro.org>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 9017dcc..96e5457 100644 (file)
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2487,11 +2487,9 @@ 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;
 
@@ -2518,8 +2516,7 @@ 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;
 }
 
@@ -2529,11 +2526,9 @@ 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;
 
@@ -2549,8 +2544,7 @@ 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;
 }
 
@@ -3008,7 +3002,6 @@ 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);
 

diff --git a/include/linux/hid.h b/include/linux/hid.h
index 5006f9b..142409f 100644 (file)
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -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;
@@ -551,7 +550,7 @@ 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 */