Re: [PATCH 1/6] tpm: Introduce a kref for the tpm_chip

On Wed, Jun 20, 2018 at 03:34:36PM -0400, Stefan Berger wrote:

On 06/20/2018 02:38 PM, Jason Gunthorpe wrote:

quoted

On Wed, Jun 20, 2018 at 12:19:43PM -0400, Stefan Berger wrote:

quoted

Introduce a kref for the tpm_chip that we initialize when the tpm_chip has
been allocated and release before the tpm_chip is to be freed.

Signed-off-by: Stefan Berger <redacted>
  drivers/char/tpm/tpm-chip.c | 24 +++++++++++++++++++-----
  drivers/char/tpm/tpm.h      |  1 +
  2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 0a62c19937b6..a933676194a4 100644
+++ b/drivers/char/tpm/tpm-chip.c

@@ -119,8 +119,24 @@ struct tpm_chip *tpm_chip_find_get(struct tpm_chip *chip)
  	return res;
  }
+static void tpm_chip_free(struct kref *kref)
+{
+	struct tpm_chip *chip = container_of(kref, struct tpm_chip, kref);
+
+	kfree(chip->log.bios_event_log);
+	kfree(chip->work_space.context_buf);
+	kfree(chip->work_space.session_buf);
+	kfree(chip);
+}
+
+static void tpm_chip_put(struct tpm_chip *chip)
+{
+	if (chip)
+		kref_put(&chip->kref, tpm_chip_free);
+}
+
  /**
- * tpm_dev_release() - free chip memory and the device number
+ * tpm_dev_release() - free the device number and release reference to chip
   * @dev: the character device for the TPM chip
   *
   * This is used as the release function for the character device.

@@ -133,10 +149,7 @@ static void tpm_dev_release(struct device *dev)
  	idr_remove(&dev_nums_idr, chip->dev_num);
  	mutex_unlock(&idr_lock);
-	kfree(chip->log.bios_event_log);
-	kfree(chip->work_space.context_buf);
-	kfree(chip->work_space.session_buf);
-	kfree(chip);
+	tpm_chip_put(chip);
  }
  static void tpm_devs_release(struct device *dev)

@@ -195,6 +208,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
  	mutex_init(&chip->tpm_mutex);
  	init_rwsem(&chip->ops_sem);
+	kref_init(&chip->kref);
  	chip->ops = ops;

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 7f2d0f489e9c..098d7dcc04a4 100644
+++ b/drivers/char/tpm/tpm.h

@@ -211,6 +211,7 @@ struct tpm_chip {
  	struct cdev cdev;
  	struct cdev cdevs;
+	struct kref kref;

NAK, there is already a kref in struct device, that one must be used.

Right. Should make it simpler...

I'll review the next version.

/Jarkko