On Mon, Mar 12, 2018 at 5:27 PM, arvindY <arvind.yadav...@gmail.com> wrote: > > > On Monday 12 March 2018 08:13 PM, David Miller wrote: >> >> From: Arvind Yadav <arvind.yadav...@gmail.com> >> Date: Fri, 9 Mar 2018 16:11:17 +0530 >> >>> if device_register() returned an error! Always use put_device() >>> to give up the reference initialized. >>> >>> Signed-off-by: Arvind Yadav <arvind.yadav...@gmail.com> >> >> I do not see anything giving cls_dev an initial non-zero reference >> count before this device_register() call. > > Yes, you are correct there is nothing to release (hnae_release).
Wait, this is not what DaveM said. Since you sent also patches to MTD I care about this too. Do we have to call put_device() in any case after a failure of device_register() or not? In this case the release function is empty, so nothing is going to released. But technically a put_device() is needed and correct according to your change log. I have to admit I don't know all details of the driver core, maybe you can help me. device_register() calls device_initialize() followed by device_add(). device_initialize() does a kobject_init() which again sets the reference counter to 1 via kref_init(). In the next step device_add() does a get_device() --> reference counter goes up to 2. But in the exit path of the function a put_device() is done, also in case of an error. So device_register() always returns with reference count 1. If I understand this correctly a put_device() is mandatory. Also in this driver. Can you please enlighten me? :-) -- Thanks, //richard
