[PATCH 3/3] drm/tegra: Support for sync file-based fences in submit

[Thierry Reding]

On Thu, Mar 09, 2017 at 07:57:18PM +0200, Mikko Perttunen wrote:
> Add support for sync file-based prefences and postfences
> to job submission. Fences are passed to the Host1x implementation.
> 
> Signed-off-by: Mikko Perttunen <mperttunen at nvidia.com>
> ---
>  drivers/gpu/drm/tegra/drm.c | 69 ++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 59 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index 64dff8530403..bf4a2a13c17d 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -10,6 +10,7 @@
>  #include <linux/bitops.h>
>  #include <linux/host1x.h>
>  #include <linux/iommu.h>
> +#include <linux/sync_file.h>
>  
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
> @@ -344,6 +345,7 @@ int tegra_drm_submit(struct tegra_drm_context *context,
>  		     struct drm_tegra_submit *args, struct drm_device *drm,
>  		     struct drm_file *file)
>  {
> +	struct host1x *host1x = dev_get_drvdata(drm->dev->parent);
>  	unsigned int num_cmdbufs = args->num_cmdbufs;
>  	unsigned int num_relocs = args->num_relocs;
>  	unsigned int num_waitchks = args->num_waitchks;
> @@ -361,6 +363,11 @@ int tegra_drm_submit(struct tegra_drm_context *context,
>  	if (args->num_syncpts != 1)
>  		return -EINVAL;
>  
> +	/* Check for unrecognized flags */
> +	if (args->flags & ~(DRM_TEGRA_SUBMIT_WAIT_FENCE_FD |
> +	                    DRM_TEGRA_SUBMIT_CREATE_FENCE_FD))
> +		return -EINVAL;
> +
>  	job = host1x_job_alloc(context->channel, args->num_cmdbufs,
>  			       args->num_relocs, args->num_waitchks);
>  	if (!job)
> @@ -372,19 +379,27 @@ int tegra_drm_submit(struct tegra_drm_context *context,
>  	job->class = context->client->base.class;
>  	job->serialize = true;
>  
> +	if (args->flags & DRM_TEGRA_SUBMIT_WAIT_FENCE_FD) {
> +		job->prefence = sync_file_get_fence(args->fence);
> +		if (!job->prefence) {
> +			err = -ENOENT;
> +			goto put_job;
> +		}
> +	}
> +
>  	while (num_cmdbufs) {
>  		struct drm_tegra_cmdbuf cmdbuf;
>  		struct host1x_bo *bo;
>  
>  		if (copy_from_user(&cmdbuf, cmdbufs, sizeof(cmdbuf))) {
>  			err = -EFAULT;
> -			goto fail;
> +			goto put_fence;
>  		}
>  
>  		bo = host1x_bo_lookup(file, cmdbuf.handle);
>  		if (!bo) {
>  			err = -ENOENT;
> -			goto fail;
> +			goto put_fence;
>  		}
>  
>  		host1x_job_add_gather(job, bo, cmdbuf.words, cmdbuf.offset);
> @@ -398,19 +413,19 @@ int tegra_drm_submit(struct tegra_drm_context *context,
>  						  &relocs[num_relocs], drm,
>  						  file);
>  		if (err < 0)
> -			goto fail;
> +			goto put_fence;
>  	}
>  
>  	if (copy_from_user(job->waitchk, waitchks,
>  			   sizeof(*waitchks) * num_waitchks)) {
>  		err = -EFAULT;
> -		goto fail;
> +		goto put_fence;
>  	}
>  
>  	if (copy_from_user(&syncpt, (void __user *)(uintptr_t)args->syncpts,
>  			   sizeof(syncpt))) {
>  		err = -EFAULT;
> -		goto fail;
> +		goto put_fence;
>  	}
>  
>  	job->is_addr_reg = context->client->ops->is_addr_reg;
> @@ -423,20 +438,54 @@ int tegra_drm_submit(struct tegra_drm_context *context,
>  
>  	err = host1x_job_pin(job, context->client->base.dev);
>  	if (err)
> -		goto fail;
> +		goto put_fence;
>  
>  	err = host1x_job_submit(job);
>  	if (err)
> -		goto fail_submit;
> +		goto unpin_job;

Shouldn't all error-unwinding gotos after this jump to the unpin_job
label as well? Seems like they all jump to put_fence instead, which I
think would leave the job pinned on failure.

>  
> -	args->fence = job->syncpt_end;
> +	if (args->flags & DRM_TEGRA_SUBMIT_CREATE_FENCE_FD) {
> +		struct dma_fence *fence;
> +		struct sync_file *file;
> +
> +		fence = host1x_fence_create(
> +			host1x, host1x_syncpt_get(host1x, job->syncpt_id),
> +			job->syncpt_end);
> +		if (!fence) {
> +			err = -ENOMEM;
> +			goto put_fence;
> +		}
> +
> +		file = sync_file_create(fence);
> +		if (!file) {
> +			dma_fence_put(fence);
> +			err = -ENOMEM;
> +			goto put_fence;
> +		}
> +
> +		err = get_unused_fd_flags(O_CLOEXEC);
> +		if (err < 0) {
> +			dma_fence_put(fence);
> +			goto put_fence;
> +		}
> +
> +		fd_install(err, file->file);
> +		args->fence = err;
> +	} else {
> +		args->fence = job->syncpt_end;
> +	}
>  
> +	if (job->prefence)
> +		dma_fence_put(job->prefence);
>  	host1x_job_put(job);
>  	return 0;
>  
> -fail_submit:
> +unpin_job:
>  	host1x_job_unpin(job);
> -fail:
> +put_fence:
> +	if (job->prefence)
> +		dma_fence_put(job->prefence);

Since we already have a conditional to check for usage of fence, I'm
wondering if we can simplify this a little and leave out the put_fence
label altogether, like so:

	unpin_job:
		host1x_job_unpin(job);
	put_job:
		if (job->prefence)
			dma_fence_put(job->prefence);

		host1x_job_put(job);

Thierry
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