Userspace could hold open a reference to the connector->kdev device,
through e.g. holding a sysfs-atrtribute open after
drm_sysfs_connector_remove() has been called. In this case the connector
could be free-ed while the connector->kdev device's drvdata is still
pointing to it.
Give drm_connector devices there own device type, which allows
us to specify our own release function and make drm_sysfs_connector_add()
take a reference on the connector object, and have the new release
function put the reference when the device is released.
Giving drm_connector devices there own device type, will also allow
checking if a device is a drm_connector device with a
"if (device->type == &drm_sysfs_device_connector)" check.
Note that the setting of the name member of the device_type struct will
cause udev events for drm_connector-s to now contain DEVTYPE=drm_connector
as extra info. So this extends the uevent part of the userspace API.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/gpu/drm/drm_sysfs.c | 54 +++++++++++++++++++++++++++++++------
1 file changed, 46 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index f0336c804639..c344c6d5e738 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -50,6 +50,10 @@ static struct device_type drm_sysfs_device_minor = {
.name = "drm_minor"
};
+static struct device_type drm_sysfs_device_connector = {
+ .name = "drm_connector",
+};
+
struct class *drm_class;
static char *drm_devnode(struct device *dev, umode_t *mode)
@@ -271,30 +275,64 @@ static const struct attribute_group *connector_dev_groups[] = {
NULL
};
+static void drm_sysfs_connector_release(struct device *dev)
+{
+ struct drm_connector *connector = to_drm_connector(dev);
+
+ drm_connector_put(connector);
+ kfree(dev);
+}
+
int drm_sysfs_connector_add(struct drm_connector *connector)
{
struct drm_device *dev = connector->dev;
+ struct device *kdev;
+ int r;
if (connector->kdev)
return 0;
- connector->kdev =
- device_create_with_groups(drm_class, dev->primary->kdev, 0,
- connector, connector_dev_groups,
- "card%d-%s", dev->primary->index,
- connector->name);
+ kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
+ if (!kdev)
+ return -ENOMEM;
+
+ device_initialize(kdev);
+ kdev->class = drm_class;
+ kdev->type = &drm_sysfs_device_connector;
+ kdev->parent = dev->primary->kdev;
+ kdev->groups = connector_dev_groups;
+ kdev->release = drm_sysfs_connector_release;
+ dev_set_drvdata(kdev, connector);
+
+ r = dev_set_name(kdev, "card%d-%s", dev->primary->index, connector->name);
+ if (r)
+ goto err_free;
+
DRM_DEBUG("adding \"%s\" to sysfs\n",
connector->name);
- if (IS_ERR(connector->kdev)) {
- DRM_ERROR("failed to register connector device: %ld\n", PTR_ERR(connector->kdev));
- return PTR_ERR(connector->kdev);
+ r = device_add(kdev);
+ if (r) {
+ DRM_ERROR("failed to register connector device: %d\n", r);
+ goto err_free;
}
+ /*
+ * Ensure the connector object does not get free-ed if userspace still has
+ * references open to the device through e.g. the connector sysfs-attributes.
+ */
+ drm_connector_get(connector);
+
+ connector->kdev = kdev;
+
if (connector->ddc)
return sysfs_create_link(&connector->kdev->kobj,
&connector->ddc->dev.kobj, "ddc");
return 0;
+
+err_free:
+ put_device(kdev);
+ return r;
}
void drm_sysfs_connector_remove(struct drm_connector *connector)
--
2.31.1
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