Re: [PATCH v3 1/2] tpm: fix reference counting for struct tpm_chip

[Lino Sanfilippo]

On 05.02.21 16:15, Jason Gunthorpe wrote:
> 
> No, the cdev layer holds the refcount on the device while open is
> being called.
> 
> Jason
> 

Yes, but the reference that is responsible for the chip deallocation is chip->dev
which is linked to chip->cdev and represents /dev/tpm, not /dev/tpmrm.
You are right, we dont have the issue with /dev/tpm for the reason you mentioned.
But /dev/tpmrm is represented by chip->cdevs and keeping this ref held by the cdev 
layer wont protect us from the chip being freed (which is the reason why we need
the chip->dev reference in the first place).

And yes, the naming dev/devs/cdev/cdevs is quite confusing  :(

Regards,
Lino