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drm: track dev_mapping in more robust and flexible way

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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: Ilija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Ilija Hadzic 2012-05-15 16:40:10 -04:00 committed by Dave Airlie
parent b97ce28e9f
commit 949c4a34af
5 changed files with 13 additions and 18 deletions
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15
drivers/gpu/drm/drm_fops.c
View file

@ -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;
}
if (dev->dev_mapping == NULL)
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;

3
drivers/gpu/drm/nouveau/nouveau_gem.c
View file

@ -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);

4
drivers/gpu/drm/radeon/radeon_object.c
View file

@ -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;
}
rdev->mman.bdev.dev_mapping = rdev->ddev->dev_mapping;
if (kernel) {
type = ttm_bo_type_kernel;
} else if (sg) {

4
drivers/gpu/drm/radeon/radeon_ttm.c
View file

@ -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;
}
rdev->mman.bdev.dev_mapping = rdev->ddev->dev_mapping;
r = radeon_ttm_debugfs_init(rdev);
if (r) {

5
drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
View file

@ -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;