media: vb2: add buf_out_validate callback

When queueing a buffer to a request the 'field' value is not validated.
That field is only validated when the _buf_prepare() is called,
which happens when the request is queued.

However, this validation should happen at QBUF time, since you want
to know about this as soon as possible. Also, the spec requires that
the 'field' value is validated at QBUF time.

This patch adds a new buf_out_validate callback to validate the
output buffer at buf_prepare time or when QBUF queues an unprepared
buffer to a request. This callback is mandatory for output queues
that support requests.

This issue was found by v4l2-compliance since it failed to replace
V4L2_FIELD_ANY by a proper field value when testing the vivid video
output in combination with requests.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/common/videobuf2/videobuf2-core.c

@@ -499,9 +499,9 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 			pr_info("     buf_init: %u buf_cleanup: %u buf_prepare: %u buf_finish: %u\n",
 				vb->cnt_buf_init, vb->cnt_buf_cleanup,
 				vb->cnt_buf_prepare, vb->cnt_buf_finish);
-			pr_info("     buf_queue: %u buf_done: %u buf_request_complete: %u\n",
-				vb->cnt_buf_queue, vb->cnt_buf_done,
-				vb->cnt_buf_request_complete);
+			pr_info("     buf_out_validate: %u buf_queue: %u buf_done: %u buf_request_complete: %u\n",
+				vb->cnt_buf_out_validate, vb->cnt_buf_queue,
+				vb->cnt_buf_done, vb->cnt_buf_request_complete);
 			pr_info("     alloc: %u put: %u prepare: %u finish: %u mmap: %u\n",
 				vb->cnt_mem_alloc, vb->cnt_mem_put,
 				vb->cnt_mem_prepare, vb->cnt_mem_finish,
@@ -1277,6 +1277,14 @@ static int __buf_prepare(struct vb2_buffer *vb)
 		return 0;
 	WARN_ON(vb->synced);
 
+	if (q->is_output) {
+		ret = call_vb_qop(vb, buf_out_validate, vb);
+		if (ret) {
+			dprintk(1, "buffer validation failed\n");
+			return ret;
+		}
+	}
+
 	vb->state = VB2_BUF_STATE_PREPARING;
 
 	switch (q->memory) {
@@ -1523,6 +1531,14 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
 			return -EINVAL;
 		}
 
+		if (q->is_output && !vb->prepared) {
+			ret = call_vb_qop(vb, buf_out_validate, vb);
+			if (ret) {
+				dprintk(1, "buffer validation failed\n");
+				return ret;
+			}
+		}
+
 		media_request_object_init(&vb->req_obj);
 
 		/* Make sure the request is in a safe state for updating. */

include/media/videobuf2-core.h

@@ -296,6 +296,7 @@ struct vb2_buffer {
 	u32		cnt_mem_num_users;
 	u32		cnt_mem_mmap;
 
+	u32		cnt_buf_out_validate;
 	u32		cnt_buf_init;
 	u32		cnt_buf_prepare;
 	u32		cnt_buf_finish;
@@ -342,6 +343,9 @@ struct vb2_buffer {
  * @wait_finish:	reacquire all locks released in the previous callback;
  *			required to continue operation after sleeping while
  *			waiting for a new buffer to arrive.
+ * @buf_out_validate:	called when the output buffer is prepared or queued
+ *			to a request; drivers can use this to validate
+ *			userspace-provided information; optional.
  * @buf_init:		called once after allocating a buffer (in MMAP case)
  *			or after acquiring a new USERPTR buffer; drivers may
  *			perform additional buffer-related initialization;
@@ -409,6 +413,7 @@ struct vb2_ops {
 	void (*wait_prepare)(struct vb2_queue *q);
 	void (*wait_finish)(struct vb2_queue *q);
 
+	int (*buf_out_validate)(struct vb2_buffer *vb);
 	int (*buf_init)(struct vb2_buffer *vb);
 	int (*buf_prepare)(struct vb2_buffer *vb);
 	void (*buf_finish)(struct vb2_buffer *vb);