c
void drm_client_register(struct drm_client_dev *client)
{
    if (!client || !client->dev) {
        pr_err("Invalid client or device\n");
        return;
    }
    
    struct drm_device *dev = client->dev;
    int ret;
    mutex_lock(&dev->clientlist_mutex);
    // ... rest of the function
}
