[PATCH v3] virtio: Add missing documentation for structure fields

[Simon Horman <horms@kernel.org>]

Add missing documentation for the vqs_list_lock field of struct virtio_device,
and the validate field of struct virtio_driver.

./scripts/kernel-doc says:

 .../virtio.h:131: warning: Function parameter or member 'vqs_list_lock' not described in 'virtio_device'
 .../virtio.h:192: warning: Function parameter or member 'validate' not described in 'virtio_driver'
 2 warnings as Errors

No functional changes intended.

Signed-off-by: Simon Horman <horms@kernel.org>
---
Changes in v3:
- As suggested by Stefano Garzarella
  + Drop inline comment for @vqs_list_lock which is now covered by Kdoc
  + Add "Returns 0 or -errno." to @validate Kdoc
- Link to v2: https://lore.kernel.org/r/20230510-virtio-kdoc-v2-1-1c5a20eb4cfe@kernel.org

Changes in v2:
- As suggested by Michael S. Tsirkin
  + @validate is not called on probe
  + @validate does validates config space
  + embarrassingly, validate was misspelt
- Link to v1: https://lore.kernel.org/r/20230510-virtio-kdoc-v1-1-d2b1824a9a2b@kernel.org
---
 include/linux/virtio.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index b93238db94e3..de6041deee37 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -103,6 +103,7 @@ int virtqueue_resize(struct virtqueue *vq, u32 num,
  * @config_enabled: configuration change reporting enabled
  * @config_change_pending: configuration change reported while disabled
  * @config_lock: protects configuration change reporting
+ * @vqs_list_lock: protects @vqs.
  * @dev: underlying device.
  * @id: the device type identification (used to match it with a driver).
  * @config: the configuration ops for this device.
@@ -117,7 +118,7 @@ struct virtio_device {
 	bool config_enabled;
 	bool config_change_pending;
 	spinlock_t config_lock;
-	spinlock_t vqs_list_lock; /* Protects VQs list access */
+	spinlock_t vqs_list_lock;
 	struct device dev;
 	struct virtio_device_id id;
 	const struct virtio_config_ops *config;
@@ -160,6 +161,8 @@ size_t virtio_max_dma_size(const struct virtio_device *vdev);
  * @feature_table_size: number of entries in the feature table array.
  * @feature_table_legacy: same as feature_table but when working in legacy mode.
  * @feature_table_size_legacy: number of entries in feature table legacy array.
+ * @validate: the function to call to validate features and config space.
+ *            Returns 0 or -errno.
  * @probe: the function to call when a device is found.  Returns 0 or -errno.
  * @scan: optional function to call after successful probe; intended
  *    for virtio-scsi to invoke a scan.