rapidio: utilize new cdev_device_add helper function

This driver did not originally set kobj.parent so it likely had
potential a use after free bug which this patch fixes.

We convert from device_register to device_initialize/cdev_device_add.
While we are at it we use put_device instead of kfree (as recommended
by the device_initialize documentation). We also remove an unnecessary
extra get_device from the code.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 8 insertions, 16 deletions

diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index 50b617af81bd..5beb0c361076 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -2444,31 +2444,25 @@ static struct mport_dev *mport_cdev_add(struct rio_mport *mport)
         mutex_init(&md->buf_mutex);
         mutex_init(&md->file_mutex);
         INIT_LIST_HEAD(&md->file_list);
-        cdev_init(&md->cdev, &mport_fops);
-        md->cdev.owner = THIS_MODULE;
-        ret = cdev_add(&md->cdev, MKDEV(MAJOR(dev_number), mport->id), 1);
-        if (ret < 0) {
-                kfree(md);
-                rmcd_error("Unable to register a device, err=%d", ret);
-                return NULL;
-        }
 
-        md->dev.devt = md->cdev.dev;
+        device_initialize(&md->dev);
+        md->dev.devt = MKDEV(MAJOR(dev_number), mport->id);
         md->dev.class = dev_class;
         md->dev.parent = &mport->dev;
         md->dev.release = mport_device_release;
         dev_set_name(&md->dev, DEV_NAME "%d", mport->id);
         atomic_set(&md->active, 1);
 
-        ret = device_register(&md->dev);
+        cdev_init(&md->cdev, &mport_fops);
+        md->cdev.owner = THIS_MODULE;
+
+        ret = cdev_device_add(&md->cdev, &md->dev);
         if (ret) {
                 rmcd_error("Failed to register mport %d (err=%d)",
                        mport->id, ret);
                 goto err_cdev;
         }
 
-        get_device(&md->dev);
-
         INIT_LIST_HEAD(&md->doorbells);
         spin_lock_init(&md->db_lock);
         INIT_LIST_HEAD(&md->portwrites);
@@ -2513,8 +2507,7 @@ static struct mport_dev *mport_cdev_add(struct rio_mport *mport)
         return md;
 
 err_cdev:
-        cdev_del(&md->cdev);
-        kfree(md);
+        put_device(&md->dev);
         return NULL;
 }
 
@@ -2578,7 +2571,7 @@ static void mport_cdev_remove(struct mport_dev *md)
         atomic_set(&md->active, 0);
         mport_cdev_terminate_dma(md);
         rio_del_mport_pw_handler(md->mport, md, rio_mport_pw_handler);
-        cdev_del(&(md->cdev));
+        cdev_device_del(&md->cdev, &md->dev);
         mport_cdev_kill_fasync(md);
 
         flush_workqueue(dma_wq);
@@ -2603,7 +2596,6 @@ static void mport_cdev_remove(struct mport_dev *md)
 
         rio_release_inb_dbell(md->mport, 0, 0x0fff);
 
-        device_unregister(&md->dev);
         put_device(&md->dev);
 }