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From:   Benjamin Gaignard <benjamin.gaignard@collabora.com>
To:     mchehab@kernel.org, tfiga@chromium.org, m.szyprowski@samsung.com,
        ming.qian@nxp.com, ezequiel@vanguardiasur.com.ar,
        p.zabel@pengutronix.de, gregkh@linuxfoundation.org,
        hverkuil-cisco@xs4all.nl, nicolas.dufresne@collabora.com
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org,
        linux-rockchip@lists.infradead.org, linux-staging@lists.linux.dev,
        kernel@collabora.com,
        Benjamin Gaignard <benjamin.gaignard@collabora.com>
Subject: [PATCH v7 20/49] media: core: Rework how create_buf index returned value is computed
Date:   Thu, 14 Sep 2023 15:32:54 +0200
Message-Id: <20230914133323.198857-21-benjamin.gaignard@collabora.com>
In-Reply-To: <20230914133323.198857-1-benjamin.gaignard@collabora.com>
References: <20230914133323.198857-1-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   | 24 +++++++++++++------
 .../media/common/videobuf2/videobuf2-v4l2.c   | 17 +++++++------
 include/media/videobuf2-core.h                |  4 +++-
 3 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 70b6b8f8c390..a4c2fae8705d 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -443,15 +443,24 @@ static void vb2_queue_remove_buffer(struct vb2_queue *q, 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 plane_sizes[VB2_MAX_PLANES],
+			     unsigned int *first)
 {
 	unsigned int buffer, plane;
 	struct vb2_buffer *vb;
+	unsigned long first_index;
 	int ret;
 
 	/* Ensure that q->num_buffers+num_buffers is below q->max_allowed_buffers */
 	num_buffers = min_t(unsigned int, num_buffers,
-			    q->max_allowed_buffers - q->num_buffers);
+			    q->max_allowed_buffers - vb2_get_num_buffers(q));
+
+	first_index = vb2_get_num_buffers(q);
+
+	if (first_index >= q->max_allowed_buffers)
+		return 0;
+
+	*first = first_index;
 
 	for (buffer = 0; buffer < num_buffers; ++buffer) {
 		/* Allocate vb2 buffer structures */
@@ -472,7 +481,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 		}
 		call_void_bufop(q, init_buffer, vb);
 
-		if (!vb2_queue_add_buffer(q, vb, q->num_buffers + buffer)) {
+		if (!vb2_queue_add_buffer(q, vb, first_index++)) {
 			dprintk(q, 1, "failed adding buffer %d to queue\n", buffer);
 			kfree(vb);
 			break;
@@ -832,7 +841,7 @@ 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;
 	int ret = 0;
 
 	if (q->streaming) {
@@ -919,7 +928,7 @@ 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);
 	if (allocated_buffers == 0) {
 		dprintk(q, 1, "memory allocation failed\n");
 		ret = -ENOMEM;
@@ -993,7 +1002,8 @@ 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)
 {
 	unsigned int num_planes = 0, num_buffers, allocated_buffers;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
@@ -1055,7 +1065,7 @@ 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);
 	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 3eb707abc26b..a88abcea2921 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -762,7 +762,6 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
 
 	fill_buf_caps(q, &create->capabilities);
 	validate_memory_flags(q, create->memory, &create->flags);
-	create->index = q->num_buffers;
 	if (create->count == 0)
 		return ret != -EBUSY ? ret : 0;
 
@@ -804,11 +803,16 @@ 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);
 
@@ -1036,7 +1040,6 @@ 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);
 	/*
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 1ecaf4b5a76f..19c93d8eb7c8 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -803,6 +803,7 @@ 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 of the first created buffer
  *
  * Videobuf2 core helper to implement VIDIOC_CREATE_BUFS() operation. It is
  * called internally by VB2 by an API-specific handler, like
@@ -819,7 +820,8 @@ 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);
 
 /**
  * vb2_core_prepare_buf() - Pass ownership of a buffer from userspace
-- 
2.39.2