[PATCH v9] dma-buf: Add ioctls to allow userspace to flush

[Chris Wilson]

On Thu, Feb 11, 2016 at 08:04:51PM -0200, Tiago Vignatti wrote:
> +static long dma_buf_ioctl(struct file *file,
> +			  unsigned int cmd, unsigned long arg)
> +{
> +	struct dma_buf *dmabuf;
> +	struct dma_buf_sync sync;
> +	enum dma_data_direction direction;
> +
> +	dmabuf = file->private_data;
> +
> +	switch (cmd) {
> +	case DMA_BUF_IOCTL_SYNC:
> +		if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
> +			return -EFAULT;
> +
> +		if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
> +			return -EINVAL;
> +
> +		switch (sync.flags & DMA_BUF_SYNC_RW) {
> +		case DMA_BUF_SYNC_READ:
> +			direction = DMA_FROM_DEVICE;
> +			break;
> +		case DMA_BUF_SYNC_WRITE:
> +			direction = DMA_TO_DEVICE;
> +			break;
> +		case DMA_BUF_SYNC_RW:
> +			direction = DMA_BIDIRECTIONAL;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		if (sync.flags & DMA_BUF_SYNC_END)
> +			dma_buf_end_cpu_access(dmabuf, direction);
> +		else
> +			dma_buf_begin_cpu_access(dmabuf, direction);

We forgot to report the error back to userspace. Might as well fixup the
callchain to propagate error from end-cpu-access as well. Found after
updating igt/gem_concurrent_blit to exercise dmabuf mmaps vs the GPU.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre