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

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- Arnd pointed out that driver_lock semaphore is superfluous, as
  driver core already provides all the necessary concurency protection.
  Removal patch from Binoy Jayan
This commit is contained in:
Jiri Kosina 2017-09-05 11:08:52 +02:00
commit 2682b89236
2 changed files with 5 additions and 13 deletions
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15
drivers/hid/hid-core.c
View file

@ -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);

3
include/linux/hid.h
View file

@ -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 */