Messages in this thread | | | Date | Mon, 10 Nov 2014 11:00:16 -0700 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v6 05/10] tpm: device class for tpm |
| |
On Mon, Nov 10, 2014 at 02:49:49PM +0200, Jarkko Sakkinen wrote:
> +static void tpm_dev_release(struct device *dev) > +{ > +} > +
These patches are so close to actually fixing many of the use-after-free problems too :)
> int tpm_dev_add_device(struct tpm_chip *chip) > { > int rc; > > - chip->vendor.miscdev.fops = &tpm_fops; > + chip->dev.class = tpm_class; > + chip->dev.release = tpm_dev_release; > + chip->dev.parent = chip->pdev; > + dev_set_name(&chip->dev, chip->devname); > + rc = device_register(&chip->dev);
I think all of this should live in tpm-chip.c
I would also suggest using device_initialize during tpmm_alloc_chip and device_add + cdev_add during tpm_register. That way the dev member is always valid and we can immediately use put_device to do the free and devm just does put_device.
> void tpm_dev_del_device(struct tpm_chip *chip) > { > - if (chip->vendor.miscdev.name) > - misc_deregister(&chip->vendor.miscdev); > + if (get_device(&chip->dev) != NULL) { > + cdev_del(&chip->cdev); > + device_unregister(&chip->dev); > + put_device(&chip->dev); > + }
The get/put seems oddly placed - really the caller of del_device must be holding the ref I don't see that del_device needs it..
Ultimately we want things so that when the ref count goes to 0 then the chip will be freed - this means that get_device can never fail since chip->dev will be deallocated memory.
> +struct class *tpm_class; > +dev_t tpm_devt;
Also makes more sense to me in chip-chip
Jason
| |