Re: [PATCH v4] tpm: fix reference counting for struct tpm_chip

From: Jarkko Sakkinen
Date: Tue Feb 16 2021 - 11:12:31 EST


On Tue, Feb 16, 2021 at 06:09:50PM +0200, Jarkko Sakkinen wrote:
> On Tue, Feb 16, 2021 at 06:04:42PM +0200, Jarkko Sakkinen wrote:
> > On Tue, Feb 16, 2021 at 08:53:42AM -0400, Jason Gunthorpe wrote:
> > > On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
> > > >
> > > > +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
> >
> > BTW, this naming is crap.
> >
> > - 2x tpm
> > - char is useless
> >
> > -> tpm2_add_device
>
> Actually, tpm2s_add_device() add put it to tpm2-space.c.

No, tpms_add_device() :-)

(sorry)

/Jarkko

>
> > > > +{
> > > > + int rc;
> > > > +
> > > > + device_initialize(&chip->devs);
> > > > + chip->devs.parent = chip->dev.parent;
> > > > + chip->devs.class = tpmrm_class;
> > > > +
> > > > + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
> > > > + if (rc)
> > > > + goto out_put_devs;
> >
> > Right, and empty line missing here.
> >
> > > > + /*
> > > > + * get extra reference on main device to hold on behalf of devs.
> > > > + * This holds the chip structure while cdevs is in use. The
> > > > + * corresponding put is in the tpm_devs_release.
> > > > + */
> > > > + get_device(&chip->dev);
> > > > + chip->devs.release = tpm_devs_release;
> > > > + chip->devs.devt =
> > > > + MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);
> >
> > Isn't this less than 100 chars?
> >
> > > > + cdev_init(&chip->cdevs, &tpmrm_fops);
> > > > + chip->cdevs.owner = THIS_MODULE;
> > > > +
> > > > + rc = cdev_device_add(&chip->cdevs, &chip->devs);
> > > > + if (rc) {
> > > > + dev_err(&chip->devs,
> > > > + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n",
> > > > + dev_name(&chip->devs), MAJOR(chip->devs.devt),
> > > > + MINOR(chip->devs.devt), rc);
> > > > + goto out_put_devs;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +
> > > > +out_put_devs:
> > > > + put_device(&chip->devs);
> > >
> > > I'd rather you organize this so chip->devs.release and the get_device
> > > is always sent instead of having the possiblity for a put_device that
> > > doesn't call release
> >
> > /Jarkko