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 <[email protected]>
Signed-off-by: Binoy Jayan <[email protected]>
Acked-by: Benjamin Tissoires <[email protected]>
Reviewed-by: David Herrmann <[email protected]>
---
v2 --> v3:
Removed reference to driver_lock in comments
v1 --> v2:
Removed driver_lock
drivers/hid/hid-core.c | 15 ++++-----------
include/linux/hid.h | 3 +--
2 files changed, 5 insertions(+), 13 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 04cee65..559533b 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2225,11 +2225,9 @@ 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;
@@ -2256,8 +2254,7 @@ 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;
}
@@ -2267,11 +2264,9 @@ 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;
@@ -2287,8 +2282,7 @@ 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;
}
@@ -2745,7 +2739,6 @@ 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);
return hdev;
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 5be325d..a49203f 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -516,7 +516,6 @@ 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;
@@ -538,7 +537,7 @@ 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 */
--
Binoy Jayan
Hi Binoy,
Looks good to me. However (and maybe Jiri can amend this while applying
the patch), the title still says "HID: Replace semaphore driver_lock
with mutex" while you killed it altogether...
Cheers,
Benjamin
On Jun 14 2017 or thereabouts, Binoy Jayan wrote:
> 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 <[email protected]>
> Signed-off-by: Binoy Jayan <[email protected]>
> Acked-by: Benjamin Tissoires <[email protected]>
> Reviewed-by: David Herrmann <[email protected]>
> ---
>
> v2 --> v3:
> Removed reference to driver_lock in comments
>
> v1 --> v2:
> Removed driver_lock
>
> drivers/hid/hid-core.c | 15 ++++-----------
> include/linux/hid.h | 3 +--
> 2 files changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 04cee65..559533b 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2225,11 +2225,9 @@ 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;
>
> @@ -2256,8 +2254,7 @@ 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;
> }
>
> @@ -2267,11 +2264,9 @@ 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;
>
> @@ -2287,8 +2282,7 @@ 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;
> }
>
> @@ -2745,7 +2739,6 @@ 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);
>
> return hdev;
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index 5be325d..a49203f 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -516,7 +516,6 @@ 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;
> @@ -538,7 +537,7 @@ 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 */
> --
> Binoy Jayan
>