[PATCH 1/5] iio: core: move to cleanup.h magic

[Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@xxxxxxxxxx>]

From: Nuno Sa <nuno.sa@xxxxxxxxxx>

Use the new cleanup magic for handling mutexes in IIO. This allows us to
greatly simplify some code paths.

Note that we keep the plain mutex calls in the
iio_device_release|acquire() APIs since in there the macros would likely
not help much (as we want to keep the lock acquired when he leave the
APIs).

Signed-off-by: Nuno Sa <nuno.sa@xxxxxxxxxx>
---
 drivers/iio/industrialio-core.c | 52 +++++++++++++++--------------------------
 1 file changed, 19 insertions(+), 33 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 9b2877fe8689..7e6497828364 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -11,6 +11,7 @@
 
 #include <linux/anon_inodes.h>
 #include <linux/cdev.h>
+#include <linux/cleanup.h>
 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/err.h>
@@ -268,20 +269,16 @@ EXPORT_SYMBOL(iio_read_const_attr);
  */
 int iio_device_set_clock(struct iio_dev *indio_dev, clockid_t clock_id)
 {
-	int ret;
 	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	const struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 
-	ret = mutex_lock_interruptible(&iio_dev_opaque->mlock);
-	if (ret)
-		return ret;
-	if ((ev_int && iio_event_enabled(ev_int)) ||
-	    iio_buffer_enabled(indio_dev)) {
-		mutex_unlock(&iio_dev_opaque->mlock);
-		return -EBUSY;
+	scoped_cond_guard(mutex_intr, return -EINTR, &iio_dev_opaque->mlock) {
+		if ((ev_int && iio_event_enabled(ev_int)) ||
+		    iio_buffer_enabled(indio_dev))
+			return -EBUSY;
+
+		iio_dev_opaque->clock_id = clock_id;
 	}
-	iio_dev_opaque->clock_id = clock_id;
-	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return 0;
 }
@@ -1806,31 +1803,22 @@ static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	struct iio_dev *indio_dev = ib->indio_dev;
 	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	struct iio_ioctl_handler *h;
-	int ret = -ENODEV;
-
-	mutex_lock(&iio_dev_opaque->info_exist_lock);
 
+	guard(mutex)(&iio_dev_opaque->info_exist_lock);
 	/*
 	 * The NULL check here is required to prevent crashing when a device
 	 * is being removed while userspace would still have open file handles
 	 * to try to access this device.
 	 */
 	if (!indio_dev->info)
-		goto out_unlock;
+		return -ENODEV;
 
 	list_for_each_entry(h, &iio_dev_opaque->ioctl_handlers, entry) {
-		ret = h->ioctl(indio_dev, filp, cmd, arg);
-		if (ret != IIO_IOCTL_UNHANDLED)
-			break;
+		if (h->ioctl(indio_dev, filp, cmd, arg) != IIO_IOCTL_UNHANDLED)
+			return 0;
 	}
 
-	if (ret == IIO_IOCTL_UNHANDLED)
-		ret = -ENODEV;
-
-out_unlock:
-	mutex_unlock(&iio_dev_opaque->info_exist_lock);
-
-	return ret;
+	return -ENODEV;
 }
 
 static const struct file_operations iio_buffer_fileops = {
@@ -2058,18 +2046,16 @@ void iio_device_unregister(struct iio_dev *indio_dev)
 
 	cdev_device_del(&iio_dev_opaque->chrdev, &indio_dev->dev);
 
-	mutex_lock(&iio_dev_opaque->info_exist_lock);
+	scoped_guard(mutex, &iio_dev_opaque->info_exist_lock) {
+		iio_device_unregister_debugfs(indio_dev);
 
-	iio_device_unregister_debugfs(indio_dev);
+		iio_disable_all_buffers(indio_dev);
 
-	iio_disable_all_buffers(indio_dev);
+		indio_dev->info = NULL;
 
-	indio_dev->info = NULL;
-
-	iio_device_wakeup_eventset(indio_dev);
-	iio_buffer_wakeup_poll(indio_dev);
-
-	mutex_unlock(&iio_dev_opaque->info_exist_lock);
+		iio_device_wakeup_eventset(indio_dev);
+		iio_buffer_wakeup_poll(indio_dev);
+	}
 
 	iio_buffers_free_sysfs_and_mask(indio_dev);
 }

-- 
2.43.0