Re: [PATCH v2 02/16] bus: mhi: core: Add support for registering MHI controllers

From: Manivannan Sadhasivam
Date: Tue Feb 11 2020 - 14:12:00 EST


Hi Greg,

On Thu, Feb 06, 2020 at 05:56:06PM +0100, Greg KH wrote:
> On Fri, Jan 31, 2020 at 07:19:55PM +0530, Manivannan Sadhasivam wrote:
> > +static void mhi_release_device(struct device *dev)
> > +{
> > + struct mhi_device *mhi_dev = to_mhi_device(dev);
> > +
> > + if (mhi_dev->ul_chan)
> > + mhi_dev->ul_chan->mhi_dev = NULL;
>
> That looks really odd. Why didn't you just drop the reference you
> should have grabbed here for this pointer? You did properly increment
> it when you saved it, right? :)
>

Well, there is no reference count (kref) exist for mhi_dev. And we really
needed to NULL the mhi_dev to avoid any dangling reference to it. The reason for
not having kref is that, each mhi_dev will be used by maximum of 2 channels
only. So thought that refcounting is not needed. Please correct me if I'm
wrong.

Thanks,
Mani

> > +
> > + if (mhi_dev->dl_chan)
> > + mhi_dev->dl_chan->mhi_dev = NULL;
>
> Same here.
>
> thanks,
>
> greg k-h