Re: [PATCH v5] dmaengine: idxd: Do not use devm for 'struct device' object allocation

Dan Williams
2021-03-24T17:02:40Z

On Wed, Mar 24, 2021 at 9:52 AM Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> On Wed, Mar 24, 2021 at 09:13:35AM -0700, Dan Williams wrote:
>
> > Which is just:
> >
> > device_initialize()
> > dev_set_name()
> >
> > ...then the name is set as early as the device is ready to filled in
> > with other details. Just checking for dev_set_name() failures does not
> > move the api forward in my opinion.
>
> This doesn't work either as the release function must be set after
> initialize but before dev_set_name(), otherwise we both can't and must
> call put_device() after something like this fails.

Ugh, true.

>
> I can't see an option other than bite the bullet and fix things.
>
> A static tool to look for these special lifetime rules around the
> driver core would be nice.

It would... it would also trip over the fact the core itself fails to
check for dev_set_name() failures and also relies on !dev_name() as a
check after-the-fact.

That check is broken if the device was not zeroed on allocate.