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SubjectRe: [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


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