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

[Seung-Woo Kim]

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.

Signed-off-by: Seung-Woo Kim <sw0312.kim at samsung.com>
Signed-off-by: Kyungmin.park <kyungmin.park at samsung.com>
Cc: Inki Dae <inki.dae at samsung.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Rob Clark <rob.clark at linaro.org>
Cc: Alex Deucher <alexander.deucher at amd.com>
---
Mmap failiure in i915 was reported by Jani, and I think it was fixed
with Dave's commit "drm/prime: add exported buffers to current fprivs
imported buffer list (v2)", so I resend this patch.

I can send exynos only, but this issue is common in all drm driver
having both prime inport and export, IMHO, it's better to send for
all drivers.

 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