drm: add minor-lookup/release helpers
Instead of accessing drm_minors_idr directly, this adds a small helper to
hide the internals. This will help us later to remove the drm_global_mutex
requirement for minor-lookup.
Furthermore, this also makes sure that minor->dev is always valid and
takes a reference-count to the device as long as the minor is used in an
open-file. This way, "struct file*"->private_data->dev is guaranteed to be
valid (which it has to, as we cannot reset it).
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 6466cb5..7947819 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -79,23 +79,22 @@
*/
int drm_open(struct inode *inode, struct file *filp)
{
- struct drm_device *dev = NULL;
- int minor_id = iminor(inode);
+ struct drm_device *dev;
struct drm_minor *minor;
- int retcode = 0;
+ int retcode;
int need_setup = 0;
struct address_space *old_mapping;
struct address_space *old_imapping;
- minor = idr_find(&drm_minors_idr, minor_id);
- if (!minor)
- return -ENODEV;
+ minor = drm_minor_acquire(iminor(inode));
+ if (IS_ERR(minor))
+ return PTR_ERR(minor);
- if (!(dev = minor->dev))
- return -ENODEV;
-
- if (drm_device_is_unplugged(dev))
- return -ENODEV;
+ dev = minor->dev;
+ if (drm_device_is_unplugged(dev)) {
+ retcode = -ENODEV;
+ goto err_release;
+ }
if (!dev->open_count++)
need_setup = 1;
@@ -128,6 +127,8 @@
dev->dev_mapping = old_mapping;
mutex_unlock(&dev->struct_mutex);
dev->open_count--;
+err_release:
+ drm_minor_release(minor);
return retcode;
}
EXPORT_SYMBOL(drm_open);
@@ -143,33 +144,33 @@
*/
int drm_stub_open(struct inode *inode, struct file *filp)
{
- struct drm_device *dev = NULL;
+ struct drm_device *dev;
struct drm_minor *minor;
- int minor_id = iminor(inode);
int err = -ENODEV;
const struct file_operations *new_fops;
DRM_DEBUG("\n");
mutex_lock(&drm_global_mutex);
- minor = idr_find(&drm_minors_idr, minor_id);
- if (!minor)
- goto out;
+ minor = drm_minor_acquire(iminor(inode));
+ if (IS_ERR(minor))
+ goto out_unlock;
- if (!(dev = minor->dev))
- goto out;
-
+ dev = minor->dev;
if (drm_device_is_unplugged(dev))
- goto out;
+ goto out_release;
new_fops = fops_get(dev->driver->fops);
if (!new_fops)
- goto out;
+ goto out_release;
replace_fops(filp, new_fops);
if (filp->f_op->open)
err = filp->f_op->open(inode, filp);
-out:
+
+out_release:
+ drm_minor_release(minor);
+out_unlock:
mutex_unlock(&drm_global_mutex);
return err;
}
@@ -453,7 +454,8 @@
int drm_release(struct inode *inode, struct file *filp)
{
struct drm_file *file_priv = filp->private_data;
- struct drm_device *dev = file_priv->minor->dev;
+ struct drm_minor *minor = file_priv->minor;
+ struct drm_device *dev = minor->dev;
int retcode = 0;
mutex_lock(&drm_global_mutex);
@@ -575,6 +577,8 @@
}
mutex_unlock(&drm_global_mutex);
+ drm_minor_release(minor);
+
return retcode;
}
EXPORT_SYMBOL(drm_release);