On Wed, 28 Feb 2018 17:39:53 +0530
Arvind Yadav <arvind.yadav.cs@xxxxxxxxx> wrote:
> On Wednesday 28 February 2018 05:26 PM, Cornelia Huck wrote:
> > On Wed, 28 Feb 2018 17:14:55 +0530
> > Arvind Yadav <arvind.yadav.cs@xxxxxxxxx> wrote:
> >
> >> On Wednesday 28 February 2018 04:00 PM, Cornelia Huck wrote:
> >>> On Wed, 28 Feb 2018 15:24:16 +0530
> >>> Arvind Yadav <arvind.yadav.cs@xxxxxxxxx> wrote:
> >>>
> >>>> Free memory, if afiucv_iucv_init is not successful and
> >>>> removing a IUCV driver.
> >>>>
> >>>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@xxxxxxxxx>
> >>>> ---
> >>>> net/iucv/af_iucv.c | 5 ++++-
> >>>> 1 file changed, 4 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
> >>>> index 1e8cc7b..eb0995a 100644
> >>>> --- a/net/iucv/af_iucv.c
> >>>> +++ b/net/iucv/af_iucv.c
> >>>> @@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
> >>>> af_iucv_dev->driver = &af_iucv_driver;
> >>>> err = device_register(af_iucv_dev);
> >>>> if (err)
> >>>> - goto out_driver;
> >>>> + goto out_iucv_dev;
> >>>> return 0;
> >>>>
> >>>> +out_iucv_dev:
> >>>> + kfree(af_iucv_dev);
> >>>> out_driver:
> >>>> driver_unregister(&af_iucv_driver);
> >>>> out_iucv:
> >>>> @@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
> >>>> {
> >>>> if (pr_iucv) {
> >>>> device_unregister(af_iucv_dev);
> >>>> + kfree(af_iucv_dev);
> >>>> driver_unregister(&af_iucv_driver);
> >>>> pr_iucv->iucv_unregister(&af_iucv_handler, 0);
> >>>> symbol_put(iucv_if);
> >>> No, you must not use kfree() after you called device_register() (even
> >>> if it was not successful!) -- see the comment for device_register().
> >> Yes, Your are right. First we need to call put_device() then kfree().
> >> I will send updated patch.
> > No, that's not correct, either. device_register() will give up any
> > reference it obtained, and the caller did not obtain any additional
> > reference, so a put_device() would be wrong. A kfree() on a refcounted
> > structure is wrong as well.
> If you will see the comment for device_register() (drivers/base/core.c)
> there is mentioned that
> 'NOTE: _Never_ directly free @dev after calling this function, even
> if it returned an error! Always use put_device() to give up the
> reference initialized in this function instead.'
> But as per you comment. we should not use.
You don't need to do a put_device() after your device_unregister(),
that's all managed by the driver core.
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