linux-kernel - Re: [PATCH 06/10] drm/tegra: Deliver job completion callback to client

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Message-ID: <a5b3d90e-6cc9-8c1a-5141-d5cb8548add9@gmail.com>
Date:   Thu, 16 Nov 2017 19:33:39 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Mikko Perttunen <mperttunen@...dia.com>, thierry.reding@...il.com,
        jonathanh@...dia.com
Cc:     dri-devel@...ts.freedesktop.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 06/10] drm/tegra: Deliver job completion callback to
 client

On 05.11.2017 14:01, Mikko Perttunen wrote:
> To allow client drivers to free resources when jobs have completed,
> deliver job completion callbacks to them. This requires adding
> reference counting to context objects, as job completion can happen
> after the userspace application has closed the context. As such,
> also add kref-based refcounting for contexts.
> 

It's very likely that we will need contexts kref'ing for other things as well,
would be nice if you could factor out kref addition into a standalone patch.

> Signed-off-by: Mikko Perttunen <mperttunen@...dia.com>
> ---
>  drivers/gpu/drm/tegra/drm.c | 27 ++++++++++++++++++++++++---
>  drivers/gpu/drm/tegra/drm.h |  4 ++++
>  2 files changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index 2cdd054520bf..3e2a4a19412e 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -281,8 +281,11 @@ static int tegra_drm_open(struct drm_device *drm, struct drm_file *filp)
>  	return 0;
>  }
>  
> -static void tegra_drm_context_free(struct tegra_drm_context *context)
> +static void tegra_drm_context_free(struct kref *ref)
>  {
> +	struct tegra_drm_context *context =
> +		container_of(ref, struct tegra_drm_context, ref);
> +
>  	context->client->ops->close_channel(context);
>  	kfree(context);
>  }
> @@ -379,6 +382,16 @@ static int host1x_waitchk_copy_from_user(struct host1x_waitchk *dest,
>  	return 0;
>  }
>  
> +static void tegra_drm_job_done(struct host1x_job *job)
> +{
> +	struct tegra_drm_context *context = job->callback_data;
> +
> +	if (context->client->ops->submit_done)
> +		context->client->ops->submit_done(context);
> +
> +	kref_put(&context->ref, tegra_drm_context_free);
> +}
> +
>  int tegra_drm_submit(struct tegra_drm_context *context,
>  		     struct drm_tegra_submit *args, struct drm_device *drm,
>  		     struct drm_file *file)
> @@ -560,6 +573,9 @@ int tegra_drm_submit(struct tegra_drm_context *context,
>  	job->syncpt_id = syncpt.id;
>  	job->timeout = 10000;
>  
> +	job->done = tegra_drm_job_done;
> +	job->callback_data = context;
> +
>  	if (args->timeout && args->timeout < 10000)
>  		job->timeout = args->timeout;
>  
> @@ -567,8 +583,11 @@ int tegra_drm_submit(struct tegra_drm_context *context,
>  	if (err)
>  		goto fail;
>  
> +	kref_get(&context->ref);
> +
>  	err = host1x_job_submit(job);
>  	if (err) {
> +		kref_put(&context->ref, tegra_drm_context_free);
>  		host1x_job_unpin(job);
>  		goto fail;
>  	}
> @@ -717,6 +736,8 @@ static int tegra_open_channel(struct drm_device *drm, void *data,
>  	if (err < 0)
>  		kfree(context);
>  
> +	kref_init(&context->ref);
> +

Would be a bit cleaner to move kref_init into tegra_client_open() where the rest
of context variables getting initialized.

>  	mutex_unlock(&fpriv->lock);
>  	return err;
>  }
> @@ -738,7 +759,7 @@ static int tegra_close_channel(struct drm_device *drm, void *data,
>  	}
>  
>  	idr_remove(&fpriv->contexts, context->id);
> -	tegra_drm_context_free(context);
> +	kref_put(&context->ref, tegra_drm_context_free);
>  
>  unlock:
>  	mutex_unlock(&fpriv->lock);
> @@ -1026,7 +1047,7 @@ static int tegra_drm_context_cleanup(int id, void *p, void *data)
>  {
>  	struct tegra_drm_context *context = p;
>  
> -	tegra_drm_context_free(context);
> +	kref_put(&context->ref, tegra_drm_context_free);
>  
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
> index 063f5d397526..079aebb3fb38 100644
> --- a/drivers/gpu/drm/tegra/drm.h
> +++ b/drivers/gpu/drm/tegra/drm.h
> @@ -13,6 +13,7 @@
>  #include <uapi/drm/tegra_drm.h>
>  #include <linux/host1x.h>
>  #include <linux/iova.h>
> +#include <linux/kref.h>
>  #include <linux/of_gpio.h>
>  
>  #include <drm/drmP.h>
> @@ -74,6 +75,8 @@ struct tegra_drm {
>  struct tegra_drm_client;
>  
>  struct tegra_drm_context {
> +	struct kref ref;
> +
>  	struct tegra_drm_client *client;
>  	struct host1x_channel *channel;
>  	unsigned int id;
> @@ -88,6 +91,7 @@ struct tegra_drm_client_ops {
>  	int (*submit)(struct tegra_drm_context *context,
>  		      struct drm_tegra_submit *args, struct drm_device *drm,
>  		      struct drm_file *file);
> +	void (*submit_done)(struct tegra_drm_context *context);
>  };
>  
>  int tegra_drm_submit(struct tegra_drm_context *context,
>