[PATCH 01/10] vfio: Move vfio_device driver open/close code to a function

[Jason Gunthorpe]

This error unwind is getting complicated. Move all the code into two
pair'd function. The functions should be called when the open_count == 1
after incrementing/before decrementing.

Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
---
 drivers/vfio/vfio_main.c | 95 ++++++++++++++++++++++------------------
 1 file changed, 53 insertions(+), 42 deletions(-)

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 2d168793d4e1ce..d043383fc3ba2b 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -734,6 +734,51 @@ bool vfio_assert_device_open(struct vfio_device *device)
 	return !WARN_ON_ONCE(!READ_ONCE(device->open_count));
 }
 
+static int vfio_device_first_open(struct vfio_device *device)
+{
+	int ret;
+
+	lockdep_assert_held(&device->dev_set->lock);
+
+	if (!try_module_get(device->dev->driver->owner))
+		return -ENODEV;
+
+	/*
+	 * Here we pass the KVM pointer with the group under the read lock.  If
+	 * the device driver will use it, it must obtain a reference and release
+	 * it during close_device.
+	 */
+	mutex_lock(&device->group->group_lock);
+	device->kvm = device->group->kvm;
+	if (device->ops->open_device) {
+		ret = device->ops->open_device(device);
+		if (ret)
+			goto err_module_put;
+	}
+	vfio_device_container_register(device);
+	mutex_unlock(&device->group->group_lock);
+	return 0;
+
+err_module_put:
+	device->kvm = NULL;
+	mutex_unlock(&device->group->group_lock);
+	module_put(device->dev->driver->owner);
+	return ret;
+}
+
+static void vfio_device_last_close(struct vfio_device *device)
+{
+	lockdep_assert_held(&device->dev_set->lock);
+
+	mutex_lock(&device->group->group_lock);
+	vfio_device_container_unregister(device);
+	if (device->ops->close_device)
+		device->ops->close_device(device);
+	device->kvm = NULL;
+	mutex_unlock(&device->group->group_lock);
+	module_put(device->dev->driver->owner);
+}
+
 static struct file *vfio_device_open(struct vfio_device *device)
 {
 	struct file *filep;
@@ -745,29 +790,12 @@ static struct file *vfio_device_open(struct vfio_device *device)
 	if (ret)
 		return ERR_PTR(ret);
 
-	if (!try_module_get(device->dev->driver->owner)) {
-		ret = -ENODEV;
-		goto err_unassign_container;
-	}
-
 	mutex_lock(&device->dev_set->lock);
 	device->open_count++;
 	if (device->open_count == 1) {
-		/*
-		 * Here we pass the KVM pointer with the group under the read
-		 * lock.  If the device driver will use it, it must obtain a
-		 * reference and release it during close_device.
-		 */
-		mutex_lock(&device->group->group_lock);
-		device->kvm = device->group->kvm;
-
-		if (device->ops->open_device) {
-			ret = device->ops->open_device(device);
-			if (ret)
-				goto err_undo_count;
-		}
-		vfio_device_container_register(device);
-		mutex_unlock(&device->group->group_lock);
+		ret = vfio_device_first_open(device);
+		if (ret)
+			goto err_unassign_container;
 	}
 	mutex_unlock(&device->dev_set->lock);
 
@@ -800,20 +828,11 @@ static struct file *vfio_device_open(struct vfio_device *device)
 
 err_close_device:
 	mutex_lock(&device->dev_set->lock);
-	mutex_lock(&device->group->group_lock);
-	if (device->open_count == 1 && device->ops->close_device) {
-		device->ops->close_device(device);
-
-		vfio_device_container_unregister(device);
-	}
-err_undo_count:
-	mutex_unlock(&device->group->group_lock);
+	if (device->open_count == 1)
+		vfio_device_last_close(device);
+err_unassign_container:
 	device->open_count--;
-	if (device->open_count == 0 && device->kvm)
-		device->kvm = NULL;
 	mutex_unlock(&device->dev_set->lock);
-	module_put(device->dev->driver->owner);
-err_unassign_container:
 	vfio_device_unassign_container(device);
 	return ERR_PTR(ret);
 }
@@ -1016,19 +1035,11 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
 
 	mutex_lock(&device->dev_set->lock);
 	vfio_assert_device_open(device);
-	mutex_lock(&device->group->group_lock);
-	if (device->open_count == 1 && device->ops->close_device)
-		device->ops->close_device(device);
-
-	vfio_device_container_unregister(device);
-	mutex_unlock(&device->group->group_lock);
+	if (device->open_count == 1)
+		vfio_device_last_close(device);
 	device->open_count--;
-	if (device->open_count == 0)
-		device->kvm = NULL;
 	mutex_unlock(&device->dev_set->lock);
 
-	module_put(device->dev->driver->owner);
-
 	vfio_device_unassign_container(device);
 
 	vfio_device_put_registration(device);
-- 
2.38.0