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

On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:

+static int tpm_add_tpm2_char_device(struct tpm_chip *chip) +{

• 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;
  

• /*

• * 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);
  

• 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

Jason