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Commit 949c4a34 authored by Ilija Hadzic's avatar Ilija Hadzic Committed by Dave Airlie
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drm: track dev_mapping in more robust and flexible way 

Setting dev_mapping (pointer to the address_space structure
used for memory mappings) to the address_space of the first
opener's inode and then failing if other openers come in
through a different inode has a few restrictions that are
eliminated by this patch.

If we already have valid dev_mapping and we spot an opener
with different i_node, we force its i_mapping pointer to the
already established address_space structure (first opener's
inode). This will make all mappings from drm device hang off
the same address_space object.

Some benefits (things that now work and didn't work
before) of this patch are:

 * user space can mknod and use any number of device
   nodes and they will all work fine as long as the major
   device number is that of the drm module.
 * user space can even remove the first opener's device
   nodes and mknod the new one and the applications and
   windowing system will still work.
 * GPU drivers can safely assume that dev->dev_mapping is
   correct address_space and just blindly copy it
   into their (private) bdev.dev_mapping

For reference, some discussion that lead to this patch can
be found here:

http://lists.freedesktop.org/archives/dri-devel/2012-April/022283.html



Signed-off-by: default avatarIlija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent b97ce28e

drivers/gpu/drm/drm_fops.c

+9 −6
Original line number Diff line number Diff line
@@ -140,12 +140,12 @@ int drm_open(struct inode *inode, struct file *filp) 
	}

	if (!retcode) {

		mutex_lock(&dev->struct_mutex);

		if (minor->type == DRM_MINOR_LEGACY) {

		if (dev->dev_mapping == NULL)

				dev->dev_mapping = inode->i_mapping;

			else if (dev->dev_mapping != inode->i_mapping)

				retcode = -ENODEV;

		}

			dev->dev_mapping = &inode->i_data;

		/* ihold ensures nobody can remove inode with our i_data */

		ihold(container_of(dev->dev_mapping, struct inode, i_data));

		inode->i_mapping = dev->dev_mapping;

		filp->f_mapping = dev->dev_mapping;

		mutex_unlock(&dev->struct_mutex);

	}
@@ -509,6 +509,9 @@ int drm_release(struct inode *inode, struct file *filp) 
		}

	}



	BUG_ON(dev->dev_mapping == NULL);

	iput(container_of(dev->dev_mapping, struct inode, i_data));



	/* drop the reference held my the file priv */

	drm_master_put(&file_priv->master);

	file_priv->is_master = 0;

drivers/gpu/drm/nouveau/nouveau_gem.c

+1 −2
Original line number Diff line number Diff line
@@ -207,8 +207,7 @@ nouveau_gem_ioctl_new(struct drm_device *dev, void *data, 
	struct nouveau_bo *nvbo = NULL;

	int ret = 0;



	if (unlikely(dev_priv->ttm.bdev.dev_mapping == NULL))

		dev_priv->ttm.bdev.dev_mapping = dev_priv->dev->dev_mapping;

	dev_priv->ttm.bdev.dev_mapping = dev->dev_mapping;



	if (!dev_priv->engine.vram.flags_valid(dev, req->info.tile_flags)) {

		NV_ERROR(dev, "bad page flags: 0x%08x\n", req->info.tile_flags);

drivers/gpu/drm/radeon/radeon_object.c

+1 −3
Original line number Diff line number Diff line
@@ -115,9 +115,7 @@ int radeon_bo_create(struct radeon_device *rdev, 


	size = ALIGN(size, PAGE_SIZE);



	if (unlikely(rdev->mman.bdev.dev_mapping == NULL)) {

	rdev->mman.bdev.dev_mapping = rdev->ddev->dev_mapping;

	}

	if (kernel) {

		type = ttm_bo_type_kernel;

	} else if (sg) {

drivers/gpu/drm/radeon/radeon_ttm.c

+1 −3
Original line number Diff line number Diff line
@@ -734,9 +734,7 @@ int radeon_ttm_init(struct radeon_device *rdev) 
	}

	DRM_INFO("radeon: %uM of GTT memory ready.\n",

		 (unsigned)(rdev->mc.gtt_size / (1024 * 1024)));

	if (unlikely(rdev->mman.bdev.dev_mapping == NULL)) {

	rdev->mman.bdev.dev_mapping = rdev->ddev->dev_mapping;

	}



	r = radeon_ttm_debugfs_init(rdev);

	if (r) {

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

+1 −4
Original line number Diff line number Diff line
@@ -769,10 +769,7 @@ static int vmw_driver_open(struct drm_device *dev, struct drm_file *file_priv) 
		goto out_no_tfile;



	file_priv->driver_priv = vmw_fp;



	if (unlikely(dev_priv->bdev.dev_mapping == NULL))

		dev_priv->bdev.dev_mapping =

			file_priv->filp->f_path.dentry->d_inode->i_mapping;

	dev_priv->bdev.dev_mapping = dev->dev_mapping;



	return 0;