Re: [PATCH] drm/prime: drop reference on imported dma-buf come from gem

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 27 Sep 2012, Seung-Woo Kim <sw0312.kim@samsung.com> wrote:
> Increasing ref counts of both dma-buf and gem for imported dma-buf come from gem
> makes memory leak. release function of dma-buf cannot be called because f_count
> of dma-buf increased by importing gem and gem ref count cannot be decrease
> because of exported dma-buf.
>
> So I add dma_buf_put() for imported gem come from its own gem into each drivers
> having prime_import and prime_export capabilities. With this, only gem ref
> count is increased if importing gem exported from gem of same driver.

There's a reference leak bug [1] related to prime self import found by
intel-gpu-tools tests. Without much thinking, I just applied this patch
to see if it makes a difference. Instead, it now fails with:

prime_self_import: prime_self_import.c:61: check_bo: Assertion `ptr1'
failed.

The assert is at [2].

I haven't looked into why this happens at all, so I'm just sharing this
in case you guys find it helpful.

BR,
Jani.



[1] https://bugs.freedesktop.org/show_bug.cgi?id=54111
[2] http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/tree/tests/prime_self_import.c#n61


>
> Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
> Signed-off-by: Kyungmin.park <kyungmin.park@samsung.com>
> Cc: Inki Dae <inki.dae@samsung.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Rob Clark <rob.clark@linaro.org>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_dmabuf.c |    5 +++++
>  drivers/gpu/drm/i915/i915_gem_dmabuf.c     |    5 +++++
>  drivers/gpu/drm/nouveau/nouveau_prime.c    |    1 +
>  drivers/gpu/drm/radeon/radeon_prime.c      |    1 +
>  drivers/staging/omapdrm/omap_gem_dmabuf.c  |    5 +++++
>  5 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> index ae13feb..b0897c9 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> @@ -211,7 +211,12 @@ struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev,
>  
>  		/* is it from our device? */
>  		if (obj->dev == drm_dev) {
> +			/*
> +			 * Importing dmabuf exported from out own gem increases
> +			 * refcount on gem itself instead of f_count of dmabuf.
> +			 */
>  			drm_gem_object_reference(obj);
> +			dma_buf_put(dma_buf);
>  			return obj;
>  		}
>  	}
> diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> index aa308e1..32e6287 100644
> --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> @@ -188,7 +188,12 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
>  		obj = dma_buf->priv;
>  		/* is it from our device? */
>  		if (obj->base.dev == dev) {
> +			/*
> +			 * Importing dmabuf exported from out own gem increases
> +			 * refcount on gem itself instead of f_count of dmabuf.
> +			 */
>  			drm_gem_object_reference(&obj->base);
> +			dma_buf_put(dma_buf);
>  			return &obj->base;
>  		}
>  	}
> diff --git a/drivers/gpu/drm/nouveau/nouveau_prime.c b/drivers/gpu/drm/nouveau/nouveau_prime.c
> index a25cf2c..bb653c6 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_prime.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_prime.c
> @@ -199,6 +199,7 @@ struct drm_gem_object *nouveau_gem_prime_import(struct drm_device *dev,
>  		if (nvbo->gem) {
>  			if (nvbo->gem->dev == dev) {
>  				drm_gem_object_reference(nvbo->gem);
> +				dma_buf_put(dma_buf);
>  				return nvbo->gem;
>  			}
>  		}
> diff --git a/drivers/gpu/drm/radeon/radeon_prime.c b/drivers/gpu/drm/radeon/radeon_prime.c
> index 6bef46a..d344a3be 100644
> --- a/drivers/gpu/drm/radeon/radeon_prime.c
> +++ b/drivers/gpu/drm/radeon/radeon_prime.c
> @@ -195,6 +195,7 @@ struct drm_gem_object *radeon_gem_prime_import(struct drm_device *dev,
>  		bo = dma_buf->priv;
>  		if (bo->gem_base.dev == dev) {
>  			drm_gem_object_reference(&bo->gem_base);
> +			dma_buf_put(dma_buf);
>  			return &bo->gem_base;
>  		}
>  	}
> diff --git a/drivers/staging/omapdrm/omap_gem_dmabuf.c b/drivers/staging/omapdrm/omap_gem_dmabuf.c
> index 42728e0..5b50eb6 100644
> --- a/drivers/staging/omapdrm/omap_gem_dmabuf.c
> +++ b/drivers/staging/omapdrm/omap_gem_dmabuf.c
> @@ -207,7 +207,12 @@ struct drm_gem_object * omap_gem_prime_import(struct drm_device *dev,
>  		obj = buffer->priv;
>  		/* is it from our device? */
>  		if (obj->dev == dev) {
> +			/*
> +			 * Importing dmabuf exported from out own gem increases
> +			 * refcount on gem itself instead of f_count of dmabuf.
> +			 */
>  			drm_gem_object_reference(obj);
> +			dma_buf_put(buffer);
>  			return obj;
>  		}
>  	}
> -- 
> 1.7.4.1
>
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