[PATCH v3 1/4] iio: core: move to cleanup.h magic

[Nuno Sa <nuno.sa@analog.com>]

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@analog.com>
---
 drivers/iio/industrialio-core.c | 34 +++++++++++++---------------------
 1 file changed, 13 insertions(+), 21 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 9b2877fe8689..e80a8065b7b9 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>
@@ -1806,31 +1807,24 @@ 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);
+	int ret;
 
+	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;
+			return ret;
 	}
 
-	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 +2052,16 @@ 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);
 }

-- 
2.44.0