tpm: fix call order in tpm-chip.c

- tpm_dev_add_device(): cdev_add() must be done before uevent is
  propagated in order to avoid races.
- tpm_chip_register(): tpm_dev_add_device() must be done as the
  last step before exposing device to the user space in order to
  avoid races.

In addition clarified description in tpm_chip_register().

Fixes: 313d21eeab92 ("tpm: device class for tpm")
Fixes: afb5abc262e9 ("tpm: two-phase chip management functions")

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

1 files changed, 14 insertions, 20 deletions

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 1d278ccd751f..e096e9cddb40 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -140,24 +140,24 @@ static int tpm_dev_add_device(struct tpm_chip *chip)
 {
         int rc;
 
-        rc = device_add(&chip->dev);
+        rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
         if (rc) {
                 dev_err(&chip->dev,
-                        "unable to device_register() %s, major %d, minor %d, err=%d\n",
+                        "unable to cdev_add() %s, major %d, minor %d, err=%d\n",
                         chip->devname, MAJOR(chip->dev.devt),
                         MINOR(chip->dev.devt), rc);
 
+                device_unregister(&chip->dev);
                 return rc;
         }
 
-        rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
+        rc = device_add(&chip->dev);
         if (rc) {
                 dev_err(&chip->dev,
-                        "unable to cdev_add() %s, major %d, minor %d, err=%d\n",
+                        "unable to device_register() %s, major %d, minor %d, err=%d\n",
                         chip->devname, MAJOR(chip->dev.devt),
                         MINOR(chip->dev.devt), rc);
 
-                device_unregister(&chip->dev);
                 return rc;
         }
 
@@ -174,27 +174,17 @@ static void tpm_dev_del_device(struct tpm_chip *chip)
  * tpm_chip_register() - create a character device for the TPM chip
  * @chip: TPM chip to use.
  *
- * Creates a character device for the TPM chip and adds sysfs interfaces for
- * the device, PPI and TCPA. As the last step this function adds the
- * chip to the list of TPM chips available for use.
+ * Creates a character device for the TPM chip and adds sysfs attributes for
+ * the device. As the last step this function adds the chip to the list of TPM
+ * chips available for in-kernel use.
  *
- * NOTE: This function should be only called after the chip initialization
- * is complete.
- *
- * Called from tpm_<specific>.c probe function only for devices
- * the driver has determined it should claim.  Prior to calling
- * this function the specific probe function has called pci_enable_device
- * upon errant exit from this function specific probe function should call
- * pci_disable_device
+ * This function should be only called after the chip initialization is
+ * complete.
  */
 int tpm_chip_register(struct tpm_chip *chip)
 {
         int rc;
 
-        rc = tpm_dev_add_device(chip);
-        if (rc)
-                return rc;
-
         /* Populate sysfs for TPM1 devices. */
         if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
                 rc = tpm_sysfs_add_device(chip);
@@ -208,6 +198,10 @@ int tpm_chip_register(struct tpm_chip *chip)
                 chip->bios_dir = tpm_bios_log_setup(chip->devname);
         }
 
+        rc = tpm_dev_add_device(chip);
+        if (rc)
+                return rc;
+
         /* Make the chip available. */
         spin_lock(&driver_lock);
         list_add_rcu(&chip->list, &tpm_chip_list);