FAILED: patch "[PATCH] drm/prime: Take a ref on the drm_dev when exporting a dma_buf" failed to apply to 4.8-stable tree

PATCH [email protected] 1 participant 1 message Oct 28, 2016

Subsystems (8)

Stable branch DRM drivers DRM misc Intel i915 +4 more subsystems

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2016-10-28 08:24 UTC #0 lore raw

The patch below does not apply to the 4.8-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From a4fce9cb782ad340ee5576a38e934e5e75832dc6 Mon Sep 17 00:00:00 2001

From: Chris Wilson <[email protected]>
Date: Wed, 5 Oct 2016 13:21:44 +0100
Subject: [PATCH] drm/prime: Take a ref on the drm_dev when exporting a dma_buf
MIME-Version: 1.0
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dma_buf may live a long time, longer than the last direct user of the driver. We already hold a reference to the owner module (that prevents the object code from disappearing), but there is no reference to the drm_dev - so the pointers to the driver backend themselves may vanish.

v2: Resist temptation to fix the bug in armada_gem.c not setting the correct flags on the exported dma-buf (it should pass the flags through and not be arbitrarily setting O_RDWR).

Use a common wrapper for exporting the dmabuf and acquiring the reference to the drm_device.

Testcase: igt/vgem_basic/unload

Signed-off-by Chris Wilson <[email protected]>

Cc Petri Latvala <[email protected]>

Cc Daniel Vetter <[email protected]>

Cc [email protected]

Tested-by Petri Latvala <[email protected]>

Reviewed-by Christian König <[email protected]>

Signed-off-by Daniel Vetter <[email protected]>

Link http://patchwork.freedesktop.org/patch/msgid/[email protected]

drivers/gpu/drm/armada/armada_gem.c +1 -1

index cb8f0347b934..a5e428d27d2f 100644
@@ -547,7 +547,7 @@ armada_gem_prime_export(struct drm_device *dev, struct drm_gem_object *obj,
 	exp_info.flags = O_RDWR;
 	exp_info.priv = obj;
 
-	return dma_buf_export(&exp_info);
+	return drm_gem_dmabuf_export(dev, &exp_info);
 }
 
 struct drm_gem_object *

drivers/gpu/drm/drm_prime.c +29 -1

index 80907b34d857..875df8d719fb 100644
@@ -284,18 +284,46 @@ static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 }
 
 /**
+ * drm_gem_dmabuf_export - dma_buf export implementation for GEM
+ * @dma_buf: buffer to be exported
+ *
+ * This wraps dma_buf_export() for use by generic GEM drivers that are using
+ * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
+ * a reference to the drm_device which is released by drm_gem_dmabuf_release().
+ *
+ * Returns the new dmabuf.
+ */
+struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
+				      struct dma_buf_export_info *exp_info)
+{
+	struct dma_buf *dma_buf;
+
+	dma_buf = dma_buf_export(exp_info);
+	if (!IS_ERR(dma_buf))
+		drm_dev_ref(dev);
+
+	return dma_buf;
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_export);
+
+/**
  * drm_gem_dmabuf_release - dma_buf release implementation for GEM
  * @dma_buf: buffer to be released
  *
  * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
  * must use this in their dma_buf ops structure as the release callback.
+ * drm_gem_dmabuf_release() should be used in conjunction with
+ * drm_gem_dmabuf_export().
  */
 void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
 {
 	struct drm_gem_object *obj = dma_buf->priv;
+	struct drm_device *dev = obj->dev;
 
 	/* drop the reference on the export fd holds */
 	drm_gem_object_unreference_unlocked(obj);
+
+	drm_dev_unref(dev);
 }
 EXPORT_SYMBOL(drm_gem_dmabuf_release);

@@ -412,7 +440,7 @@ struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
 	if (dev->driver->gem_prime_res_obj)
 		exp_info.resv = dev->driver->gem_prime_res_obj(obj);
 
-	return dma_buf_export(&exp_info);
+	return drm_gem_dmabuf_export(dev, &exp_info);
 }
 EXPORT_SYMBOL(drm_gem_prime_export);

drivers/gpu/drm/i915/i915_gem_dmabuf.c +1 -1

index 10265bb35604..97c9d68b45df 100644
@@ -283,7 +283,7 @@ struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
 			return ERR_PTR(ret);
 	}
 
-	dma_buf = dma_buf_export(&exp_info);
+	dma_buf = drm_gem_dmabuf_export(dev, &exp_info);
 	if (IS_ERR(dma_buf))
 		return dma_buf;

drivers/gpu/drm/tegra/gem.c +1 -1

index aa60d9909ea2..95e622e31931 100644
@@ -613,7 +613,7 @@ struct dma_buf *tegra_gem_prime_export(struct drm_device *drm,
 	exp_info.flags = flags;
 	exp_info.priv = gem;
 
-	return dma_buf_export(&exp_info);
+	return drm_gem_dmabuf_export(drm, &exp_info);
 }
 
 struct drm_gem_object *tegra_gem_prime_import(struct drm_device *drm,

drivers/gpu/drm/udl/udl_dmabuf.c +1 -1

index e2243edd1ce3..ac90ffdb5912 100644
@@ -209,7 +209,7 @@ struct dma_buf *udl_gem_prime_export(struct drm_device *dev,
 	exp_info.flags = flags;
 	exp_info.priv = obj;
 
-	return dma_buf_export(&exp_info);
+	return drm_gem_dmabuf_export(dev, &exp_info);
 }
 
 static int udl_prime_create(struct drm_device *dev,

include/drm/drmP.h +4 -0

index 81fcd553edf7..672644031bd5 100644
@@ -1011,6 +1011,8 @@ static inline int drm_debugfs_remove_files(const struct drm_info_list *files,
 }
 #endif
 
+struct dma_buf_export_info;
+
 extern struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
 					    struct drm_gem_object *obj,
 					    int flags);

@@ -1021,6 +1023,8 @@ extern struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 		struct dma_buf *dma_buf);
 extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 		struct drm_file *file_priv, int prime_fd, uint32_t *handle);
+struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
+				      struct dma_buf_export_info *exp_info);
 extern void drm_gem_dmabuf_release(struct dma_buf *dma_buf);
 
 extern int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,