diff options
| author | David Herrmann <dh.herrmann@gmail.com> | 2014-01-29 10:21:36 +0100 |
|---|---|---|
| committer | David Herrmann <dh.herrmann@gmail.com> | 2014-03-16 12:25:17 +0100 |
| commit | 099d1c290e2ebc3b798961a6c177c3aef5f0b789 (patch) | |
| tree | 4b0d0a693d5c08081e72cd24294d9d312b14a107 /include/drm | |
| parent | cb8a239b03608079cbfb784e9ac2f522fe846c29 (diff) | |
drm: provide device-refcount
Lets not trick ourselves into thinking "drm_device" objects are not
ref-counted. That's just utterly stupid. We manage "drm_minor" objects on
each drm-device and each minor can have an unlimited number of open
handles. Each of these handles has the drm_minor (and thus the drm_device)
as private-data in the file-handle. Therefore, we may not destroy
"drm_device" until all these handles are closed.
It is *not* possible to reset all these pointers atomically and restrict
access to them, and this is *not* how this is done! Instead, we use
ref-counts to make sure the object is valid and not freed.
Note that we currently use "dev->open_count" for that, which is *exactly*
the same as a reference-count, just open coded. So this patch doesn't
change any semantics on DRM devices (well, this patch just introduces the
ref-count, anyway. Follow-up patches will replace open_count by it).
Also note that generic VFS revoke support could allow us to drop this
ref-count again. We could then just synchronously disable any fops->xy()
calls. However, this is not the case, yet, and no such patches are
in sight (and I seriously question the idea of dropping the ref-cnt
again).
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Diffstat (limited to 'include/drm')
| -rw-r--r-- | include/drm/drmP.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/drm/drmP.h b/include/drm/drmP.h index 2c322564ca7d..4e53f1607355 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -43,6 +43,7 @@ #include <asm/current.h> #endif /* __alpha__ */ #include <linux/kernel.h> +#include <linux/kref.h> #include <linux/miscdevice.h> #include <linux/fs.h> #include <linux/init.h> @@ -1102,6 +1103,7 @@ struct drm_device { /** \name Lifetime Management */ /*@{ */ + struct kref ref; /**< Object ref-count */ struct device *dev; /**< Device structure of bus-device */ struct drm_driver *driver; /**< DRM driver managing the device */ void *dev_private; /**< DRM driver private data */ @@ -1666,7 +1668,8 @@ static __inline__ void drm_core_dropmap(struct drm_local_map *map) struct drm_device *drm_dev_alloc(struct drm_driver *driver, struct device *parent); -void drm_dev_free(struct drm_device *dev); +void drm_dev_ref(struct drm_device *dev); +void drm_dev_unref(struct drm_device *dev); int drm_dev_register(struct drm_device *dev, unsigned long flags); void drm_dev_unregister(struct drm_device *dev); /*@}*/ |