[PATCH 11/14] rapidio: utilize new device_add_cdev helper function

Logan Gunthorpe
2017-02-21T05:00:50Z

Note: the chardev instance in rio_mport_cdev originally did not
set the kobject parent. Thus, I'm reasonably confident that because
of this, this code would have suffered from a minor use after free
bug if the cdev was open when the backing device was released.

Signed-off-by: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
---
drivers/rapidio/devices/rio_mport_cdev.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index 9013a58..10a6b54 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -2445,23 +2445,26 @@ 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);
+
+ device_initialize(&md->dev);
+ md->dev.devt = MKDEV(MAJOR(dev_number), mport->id);
+
cdev_init(&md->cdev, &mport_fops);
md->cdev.owner = THIS_MODULE;
- ret = cdev_add(&md->cdev, MKDEV(MAJOR(dev_number), mport->id), 1);
+ ret = device_add_cdev(&md->dev, &md->cdev);
if (ret < 0) {
kfree(md);
rmcd_error("Unable to register a device, err=%d", ret);
return NULL;
}

- md->dev.devt = md->cdev.dev;
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);
+ ret = device_add(&md->dev);
if (ret) {
rmcd_error("Failed to register mport %d (err=%d)",
mport->id, ret);
--
2.1.4