diff mbox series

[PATCHv6,7/8] videobuf2: handle V4L2_MEMORY_FLAG_NON_COHERENT flag

Message ID 20210909112430.61243-8-senozhatsky@chromium.org
State Accepted
Commit c0acf9cfeee061f041fab778dbdcb34b6ca5e2e7
Headers show
Series videobuf2: support new noncontiguous DMA API | expand

Commit Message

Sergey Senozhatsky Sept. 9, 2021, 11:24 a.m. UTC
This patch lets user-space request a non-coherent memory
allocation during CREATE_BUFS and REQBUFS ioctl calls.

= CREATE_BUFS

  struct v4l2_create_buffers has seven 4-byte reserved areas,
  so reserved[0] is renamed to ->flags. The struct, thus, now
  has six reserved 4-byte regions.

= CREATE_BUFS32

  struct v4l2_create_buffers32 has seven 4-byte reserved areas,
  so reserved[0] is renamed to ->flags. The struct, thus, now
  has six reserved 4-byte regions.

= REQBUFS

 We use one byte of a 4 byte ->reserved[1] member of struct
 v4l2_requestbuffers. The struct, thus, now has reserved 3 bytes.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 .../media/v4l/vidioc-create-bufs.rst          |  7 ++++-
 .../media/v4l/vidioc-reqbufs.rst              | 11 ++++---
 .../media/common/videobuf2/videobuf2-core.c   |  4 +--
 .../media/common/videobuf2/videobuf2-v4l2.c   | 31 +++++++++++++++++--
 drivers/media/v4l2-core/v4l2-compat-ioctl32.c |  9 +++++-
 drivers/media/v4l2-core/v4l2-ioctl.c          |  4 +--
 include/uapi/linux/videodev2.h                |  9 ++++--
 7 files changed, 60 insertions(+), 15 deletions(-)

Comments

Sergey Senozhatsky Sept. 28, 2021, 4:50 a.m. UTC | #1
On (21/09/09 20:24), Sergey Senozhatsky wrote:
[..]
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h

> index 9b7032abb2c7..f118fe7a9f58 100644

> --- a/include/uapi/linux/videodev2.h

> +++ b/include/uapi/linux/videodev2.h

> @@ -959,7 +959,8 @@ struct v4l2_requestbuffers {

>  	__u32			type;		/* enum v4l2_buf_type */

>  	__u32			memory;		/* enum v4l2_memory */

>  	__u32			capabilities;

> -	__u32			reserved[1];

> +	__u8			flags;

> +	__u8			reserved[3];

>  };


[..]

>  struct v4l2_create_buffers {

> @@ -2515,7 +2519,8 @@ struct v4l2_create_buffers {

>  	__u32			memory;

>  	struct v4l2_format	format;

>  	__u32			capabilities;

> -	__u32			reserved[7];

> +	__u32			flags;

> +	__u32			reserved[6];

>  };


These UAPI changes break strace compilation (older versions). Up until
Feb 2021 strace had compile time asserts that check-ed sizeof() ->reserved
fields.

  static_assert failed due to requirement
   '(sizeof (((struct v4l2_create_buffers *)0)->reserved)) >= (sizeof (((struct_v4l2_create_buffers *)0)->reserved))'
   "Unexpected struct v4l2_create_buffers.reserved size, please update the decoder"

It seems that strace has dropped those assertions

https://github.com/strace/strace/commit/e5554291d14b852f61385ba5ba59412d133ac99d#diff-d534423e8a79b6957ef4deb7f8bbd3276bf18ede6a82553e8823ee4f840b6e06


But we, probably, need to use unions in UAPI. Any thoughts?
diff mbox series

Patch

diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
index f98f18c9e91c..a048a9f6b7b6 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
@@ -113,7 +113,12 @@  than the number requested.
 	``V4L2_MEMORY_MMAP`` and ``format.type`` to the buffer type.
 
     * - __u32
-      - ``reserved``\ [7]
+      - ``flags``
+      - Specifies additional buffer management attributes.
+	See :ref:`memory-flags`.
+
+    * - __u32
+      - ``reserved``\ [6]
       - A place holder for future extensions. Drivers and applications
 	must set the array to zero.
 
diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
index e59306aba2b0..099fa6695167 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
@@ -104,10 +104,13 @@  aborting or finishing any DMA in progress, an implicit
 	``V4L2_MEMORY_MMAP`` and ``type`` set to the buffer type. This will
 	free any previously allocated buffers, so this is typically something
 	that will be done at the start of the application.
-    * - __u32
-      - ``reserved``\ [1]
-      - A place holder for future extensions. Drivers and applications
-	must set the array to zero.
+    * - __u8
+      - ``flags``
+      - Specifies additional buffer management attributes.
+	See :ref:`memory-flags`.
+    * - __u8
+      - ``reserved``\ [3]
+      - Reserved for future extensions.
 
 .. _v4l2-buf-capabilities:
 .. _V4L2-BUF-CAP-SUPPORTS-MMAP:
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 60fb43b8f134..2266bbd239ab 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -761,7 +761,7 @@  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 {
 	unsigned int num_buffers, allocated_buffers, num_planes = 0;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
-	bool non_coherent_mem = false;
+	bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
 	unsigned int i;
 	int ret;
 
@@ -905,7 +905,7 @@  int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 {
 	unsigned int num_planes = 0, num_buffers, allocated_buffers;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
-	bool non_coherent_mem = false;
+	bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
 	int ret;
 
 	if (q->num_buffers == VB2_MAX_FRAME) {
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index b4f70ddb09b0..6edf4508c636 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -692,12 +692,32 @@  static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
 #endif
 }
 
+static void validate_memory_flags(struct vb2_queue *q,
+				  int memory,
+				  u32 *flags)
+{
+	if (!q->allow_cache_hints || memory != V4L2_MEMORY_MMAP) {
+		/*
+		 * This needs to clear V4L2_MEMORY_FLAG_NON_COHERENT only,
+		 * but in order to avoid bugs we zero out all bits.
+		 */
+		*flags = 0;
+	} else {
+		/* Clear all unknown flags. */
+		*flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
+	}
+}
+
 int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 {
 	int ret = vb2_verify_memory_type(q, req->memory, req->type);
+	u32 flags = req->flags;
 
 	fill_buf_caps(q, &req->capabilities);
-	return ret ? ret : vb2_core_reqbufs(q, req->memory, 0, &req->count);
+	validate_memory_flags(q, req->memory, &flags);
+	req->flags = flags;
+	return ret ? ret : vb2_core_reqbufs(q, req->memory,
+					    req->flags, &req->count);
 }
 EXPORT_SYMBOL_GPL(vb2_reqbufs);
 
@@ -729,6 +749,7 @@  int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
 	unsigned i;
 
 	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;
@@ -772,7 +793,7 @@  int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
 		if (requested_sizes[i] == 0)
 			return -EINVAL;
 	return ret ? ret : vb2_core_create_bufs(q, create->memory,
-						0,
+						create->flags,
 						&create->count,
 						requested_planes,
 						requested_sizes);
@@ -969,13 +990,16 @@  int vb2_ioctl_reqbufs(struct file *file, void *priv,
 {
 	struct video_device *vdev = video_devdata(file);
 	int res = vb2_verify_memory_type(vdev->queue, p->memory, p->type);
+	u32 flags = p->flags;
 
 	fill_buf_caps(vdev->queue, &p->capabilities);
+	validate_memory_flags(vdev->queue, p->memory, &flags);
+	p->flags = flags;
 	if (res)
 		return res;
 	if (vb2_queue_is_busy(vdev, file))
 		return -EBUSY;
-	res = vb2_core_reqbufs(vdev->queue, p->memory, 0, &p->count);
+	res = vb2_core_reqbufs(vdev->queue, p->memory, p->flags, &p->count);
 	/* If count == 0, then the owner has released all buffers and he
 	   is no longer owner of the queue. Otherwise we have a new owner. */
 	if (res == 0)
@@ -993,6 +1017,7 @@  int vb2_ioctl_create_bufs(struct file *file, void *priv,
 
 	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.
diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
index 47aff3b19742..8176769a89fa 100644
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -126,6 +126,9 @@  struct v4l2_format32 {
  * @memory:	buffer memory type
  * @format:	frame format, for which buffers are requested
  * @capabilities: capabilities of this buffer type.
+ * @flags:	additional buffer management attributes (ignored unless the
+ *		queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability and
+ *		configured for MMAP streaming I/O).
  * @reserved:	future extensions
  */
 struct v4l2_create_buffers32 {
@@ -134,7 +137,8 @@  struct v4l2_create_buffers32 {
 	__u32			memory;	/* enum v4l2_memory */
 	struct v4l2_format32	format;
 	__u32			capabilities;
-	__u32			reserved[7];
+	__u32			flags;
+	__u32			reserved[6];
 };
 
 static int get_v4l2_format32(struct v4l2_format *p64,
@@ -182,6 +186,8 @@  static int get_v4l2_create32(struct v4l2_create_buffers *p64,
 	if (copy_from_user(p64, p32,
 			   offsetof(struct v4l2_create_buffers32, format)))
 		return -EFAULT;
+	if (copy_from_user(&p64->flags, &p32->flags, sizeof(p32->flags)))
+		return -EFAULT;
 	return get_v4l2_format32(&p64->format, &p32->format);
 }
 
@@ -227,6 +233,7 @@  static int put_v4l2_create32(struct v4l2_create_buffers *p64,
 	if (copy_to_user(p32, p64,
 			 offsetof(struct v4l2_create_buffers32, format)) ||
 	    put_user(p64->capabilities, &p32->capabilities) ||
+	    put_user(p64->flags, &p32->flags) ||
 	    copy_to_user(p32->reserved, p64->reserved, sizeof(p64->reserved)))
 		return -EFAULT;
 	return put_v4l2_format32(&p64->format, &p32->format);
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index d4f97ab1b237..842ad84490ca 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -2006,7 +2006,7 @@  static int v4l_reqbufs(const struct v4l2_ioctl_ops *ops,
 	if (ret)
 		return ret;
 
-	CLEAR_AFTER_FIELD(p, capabilities);
+	CLEAR_AFTER_FIELD(p, flags);
 
 	return ops->vidioc_reqbufs(file, fh, p);
 }
@@ -2047,7 +2047,7 @@  static int v4l_create_bufs(const struct v4l2_ioctl_ops *ops,
 	if (ret)
 		return ret;
 
-	CLEAR_AFTER_FIELD(create, capabilities);
+	CLEAR_AFTER_FIELD(create, flags);
 
 	v4l_sanitize_format(&create->format);
 
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 9b7032abb2c7..f118fe7a9f58 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -959,7 +959,8 @@  struct v4l2_requestbuffers {
 	__u32			type;		/* enum v4l2_buf_type */
 	__u32			memory;		/* enum v4l2_memory */
 	__u32			capabilities;
-	__u32			reserved[1];
+	__u8			flags;
+	__u8			reserved[3];
 };
 
 #define V4L2_MEMORY_FLAG_NON_COHERENT			(1 << 0)
@@ -2507,6 +2508,9 @@  struct v4l2_dbg_chip_info {
  * @memory:	enum v4l2_memory; buffer memory type
  * @format:	frame format, for which buffers are requested
  * @capabilities: capabilities of this buffer type.
+ * @flags:	additional buffer management attributes (ignored unless the
+ *		queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability
+ *		and configured for MMAP streaming I/O).
  * @reserved:	future extensions
  */
 struct v4l2_create_buffers {
@@ -2515,7 +2519,8 @@  struct v4l2_create_buffers {
 	__u32			memory;
 	struct v4l2_format	format;
 	__u32			capabilities;
-	__u32			reserved[7];
+	__u32			flags;
+	__u32			reserved[6];
 };
 
 /*