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From: Benjamin Gaignard <benjamin.gaignard@collabora.com>
To: hverkuil@xs4all.nl,
	mchehab@kernel.org
Cc: linux-kernel@vger.kernel.org,
	linux-media@vger.kernel.org,
	kernel@collabora.com,
	Benjamin Gaignard <benjamin.gaignard@collabora.com>
Subject: [PATCH v16 3/8] media: core: Rework how create_buf index returned value is computed
Date: Fri, 15 Dec 2023 10:08:08 +0100
Message-Id: <20231215090813.15610-4-benjamin.gaignard@collabora.com>
In-Reply-To: <20231215090813.15610-1-benjamin.gaignard@collabora.com>
References: <20231215090813.15610-1-benjamin.gaignard@collabora.com>
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When DELETE_BUFS will be introduced holes could created in bufs array.
To be able to reuse these unused indices reworking how create->index
is set is mandatory.
Let __vb2_queue_alloc() decide which first index is correct and
forward this to the caller.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
 .../media/common/videobuf2/videobuf2-core.c   | 22 ++++++++++++-------
 .../media/common/videobuf2/videobuf2-v4l2.c   | 20 +++++++++++------
 include/media/videobuf2-core.h                |  5 ++++-
 3 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index a183edf11586..cd2b9e51b9b0 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -447,11 +447,12 @@ static void vb2_queue_remove_buffer(struct vb2_buffer *vb)
  */
 static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 			     unsigned int num_buffers, unsigned int num_planes,
-			     const unsigned plane_sizes[VB2_MAX_PLANES])
+			     const unsigned int plane_sizes[VB2_MAX_PLANES],
+			     unsigned int *first_index)
 {
-	unsigned int q_num_buffers = vb2_get_num_buffers(q);
 	unsigned int buffer, plane;
 	struct vb2_buffer *vb;
+	unsigned long index;
 	int ret;
 
 	/*
@@ -459,7 +460,11 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 	 * in the queue is below q->max_num_buffers
 	 */
 	num_buffers = min_t(unsigned int, num_buffers,
-			    q->max_num_buffers - q_num_buffers);
+			    q->max_num_buffers - vb2_get_num_buffers(q));
+
+	index = vb2_get_num_buffers(q);
+
+	*first_index = index;
 
 	for (buffer = 0; buffer < num_buffers; ++buffer) {
 		/* Allocate vb2 buffer structures */
@@ -479,7 +484,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 			vb->planes[plane].min_length = plane_sizes[plane];
 		}
 
-		vb2_queue_add_buffer(q, vb, q_num_buffers + buffer);
+		vb2_queue_add_buffer(q, vb, index++);
 		call_void_bufop(q, init_buffer, vb);
 
 		/* Allocate video buffer memory for the MMAP type */
@@ -820,7 +825,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	unsigned int q_num_bufs = vb2_get_num_buffers(q);
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
 	bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
-	unsigned int i;
+	unsigned int i, first_index;
 	int ret = 0;
 
 	if (q->streaming) {
@@ -906,7 +911,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 
 	/* Finally, allocate buffers and video memory */
 	allocated_buffers =
-		__vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes);
+		__vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes, &first_index);
 	if (allocated_buffers == 0) {
 		dprintk(q, 1, "memory allocation failed\n");
 		ret = -ENOMEM;
@@ -980,7 +985,8 @@ EXPORT_SYMBOL_GPL(vb2_core_reqbufs);
 int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 			 unsigned int flags, unsigned int *count,
 			 unsigned int requested_planes,
-			 const unsigned int requested_sizes[])
+			 const unsigned int requested_sizes[],
+			 unsigned int *first_index)
 {
 	unsigned int num_planes = 0, num_buffers, allocated_buffers;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
@@ -1042,7 +1048,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 
 	/* Finally, allocate buffers and video memory */
 	allocated_buffers = __vb2_queue_alloc(q, memory, num_buffers,
-				num_planes, plane_sizes);
+				num_planes, plane_sizes, first_index);
 	if (allocated_buffers == 0) {
 		dprintk(q, 1, "memory allocation failed\n");
 		ret = -ENOMEM;
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 54d572c3b515..3c0c423c5674 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -797,11 +797,16 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
 	for (i = 0; i < requested_planes; i++)
 		if (requested_sizes[i] == 0)
 			return -EINVAL;
-	return ret ? ret : vb2_core_create_bufs(q, create->memory,
-						create->flags,
-						&create->count,
-						requested_planes,
-						requested_sizes);
+	if (ret)
+		return ret;
+
+	ret = vb2_core_create_bufs(q, create->memory,
+				   create->flags,
+				   &create->count,
+				   requested_planes,
+				   requested_sizes,
+				   &create->index);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(vb2_create_bufs);
 
@@ -1029,15 +1034,16 @@ int vb2_ioctl_create_bufs(struct file *file, void *priv,
 	int res = vb2_verify_memory_type(vdev->queue, p->memory,
 			p->format.type);
 
-	p->index = vdev->queue->num_buffers;
 	fill_buf_caps(vdev->queue, &p->capabilities);
 	validate_memory_flags(vdev->queue, p->memory, &p->flags);
 	/*
 	 * If count == 0, then just check if memory and type are valid.
 	 * Any -EBUSY result from vb2_verify_memory_type can be mapped to 0.
 	 */
-	if (p->count == 0)
+	if (p->count == 0) {
+		p->index = vb2_get_num_buffers(vdev->queue);
 		return res != -EBUSY ? res : 0;
+	}
 	if (res)
 		return res;
 	if (vb2_queue_is_busy(vdev->queue, file))
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 7b84b4e2e273..607f2ba7a905 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -821,6 +821,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
  * @count: requested buffer count.
  * @requested_planes: number of planes requested.
  * @requested_sizes: array with the size of the planes.
+ * @first_index: index of the first created buffer, all allocated buffers have
+ *		 indices in the range [first..first+count]
  *
  * Videobuf2 core helper to implement VIDIOC_CREATE_BUFS() operation. It is
  * called internally by VB2 by an API-specific handler, like
@@ -837,7 +839,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 			 unsigned int flags, unsigned int *count,
 			 unsigned int requested_planes,
-			 const unsigned int requested_sizes[]);
+			 const unsigned int requested_sizes[],
+			 unsigned int *first_index);
 
 /**
  * vb2_core_prepare_buf() - Pass ownership of a buffer from userspace
-- 
2.40.1