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

On Thu, Feb 25, 2016 at 06:01:22PM +0000, Chris Wilson wrote:

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.

EINTR? Do we need to make this ABI - I guess so? Tiago, do you have patches? See drmIoctl() in libdrm for what's needed on the userspace side if my guess is right. -Daniel