On 5/13/25 11:27, wangtao wrote:
> Add DMA_BUF_IOCTL_RW_FILE to save/restore data from/to a dma-buf.
Similar approach where rejected before in favor of using udmabuf.
Is there any reason you can't use that approach as well?
Regards,
Christian.
>
> Signed-off-by: wangtao <tao.wang...@honor.com>
> ---
> drivers/dma-buf/dma-buf.c | 8 ++++++++
> include/linux/dma-buf.h | 3 +++
> include/uapi/linux/dma-buf.h | 29 +++++++++++++++++++++++++++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 5baa83b85515..95d8b0158ffd 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -460,6 +460,7 @@ static long dma_buf_ioctl(struct file *file,
> struct dma_buf *dmabuf;
> struct dma_buf_sync sync;
> enum dma_data_direction direction;
> + struct dma_buf_rw_file kfile;
> int ret;
>
> dmabuf = file->private_data;
> @@ -504,6 +505,13 @@ static long dma_buf_ioctl(struct file *file,
> return dma_buf_import_sync_file(dmabuf, (const void __user
> *)arg);
> #endif
>
> + case DMA_BUF_IOCTL_RW_FILE:
> + if (copy_from_user(&kfile, (void __user *) arg, sizeof(kfile)))
> + return -EFAULT;
> + if (!dmabuf->ops->rw_file)
> + return -EINVAL;
> + return dmabuf->ops->rw_file(dmabuf, &kfile);
> +
> default:
> return -ENOTTY;
> }
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index 36216d28d8bd..de236ba2094b 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -22,6 +22,7 @@
> #include <linux/fs.h>
> #include <linux/dma-fence.h>
> #include <linux/wait.h>
> +#include <uapi/linux/dma-buf.h>
>
> struct device;
> struct dma_buf;
> @@ -285,6 +286,8 @@ struct dma_buf_ops {
>
> int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map);
> void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map *map);
> +
> + int (*rw_file)(struct dma_buf *dmabuf, struct dma_buf_rw_file *file);
> };
>
> /**
> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
> index 5a6fda66d9ad..ec9164b7b753 100644
> --- a/include/uapi/linux/dma-buf.h
> +++ b/include/uapi/linux/dma-buf.h
> @@ -167,6 +167,29 @@ struct dma_buf_import_sync_file {
> __s32 fd;
> };
>
> +/**
> + * struct dma_buf_rw_file - read/write file associated with a dma-buf
> + *
> + * Userspace can performs a DMA_BUF_IOCTL_BACK to save data from a dma-buf or
> + * restore data to a dma-buf.
> + */
> +struct dma_buf_rw_file {
> +
> + /** @flags: Flags indicating read/write for this dma-buf. */
> + __u32 flags;
> + /** @fd: File descriptor of the file associated with this dma-buf. */
> + __s32 fd;
> + /** @file_offset: Offset within the file where this dma-buf starts.
> + *
> + * Offset and Length must be page-aligned for direct I/O.
> + */
> + __u64 file_offset;
> + /** @buf_offset: Offset within this dma-buf where the read/write
> starts. */
> + __u64 buf_offset;
> + /** @buf_len: Length of this dma-buf read/write. */
> + __u64 buf_len;
> +};
> +
> #define DMA_BUF_BASE 'b'
> #define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
>
> @@ -179,4 +202,10 @@ struct dma_buf_import_sync_file {
> #define DMA_BUF_IOCTL_EXPORT_SYNC_FILE _IOWR(DMA_BUF_BASE, 2, struct
> dma_buf_export_sync_file)
> #define DMA_BUF_IOCTL_IMPORT_SYNC_FILE _IOW(DMA_BUF_BASE, 3, struct
> dma_buf_import_sync_file)
>
> +#define DMA_BUF_RW_FLAGS_OP_MASK (0xFF << 0)
> +#define DMA_BUF_RW_FLAGS_READ (1 << 0) /* Restore dma-buf data */
> +#define DMA_BUF_RW_FLAGS_WRITE (2 << 0) /* Save dma-buf data */
> +#define DMA_BUF_RW_FLAGS_DIRECT (1u << 31) /* Direct read/write file */
> +#define DMA_BUF_IOCTL_RW_FILE _IOW(DMA_BUF_BASE, 4, struct
> dma_buf_rw_file)
> +
> #endif
