TPM: update char dev BKL pushdown

This patch removes the BKL calls from the TPM driver, which were added in the overall misc-char-dev-BKL-pushdown.patch, as they are not needed. Changed num_opens from an int to atomic_t.

Signed-off-by Mimi Zohar <[email protected]>

Signed-off-by Rajiv Andrade <[email protected]>

---
 drivers/char/tpm/tpm.c |   22 +++++++---------------
 drivers/char/tpm/tpm.h |    2 +-
 2 files changed, 8 insertions(+), 16 deletions(-)

drivers/char/tpm/tpm.c +7 -15

index ae766d8..cd4ff36 100644
@@ -960,7 +960,6 @@ int tpm_open(struct inode *inode, struct file *file)
 	int rc = 0, minor = iminor(inode);
 	struct tpm_chip *chip = NULL, *pos;
 
-	lock_kernel();
 	spin_lock(&driver_lock);
 
 	list_for_each_entry(pos, &tpm_chip_list, list) {

@@ -975,34 +974,31 @@ int tpm_open(struct inode *inode, struct file *file)
 		goto err_out;
 	}
 
-	if (chip->num_opens) {
+	if (atomic_read(&chip->num_opens)) {
 		dev_dbg(chip->dev, "Another process owns this TPM\n");
 		rc = -EBUSY;
 		goto err_out;
 	}
 
-	chip->num_opens++;
+	atomic_inc(&chip->num_opens);
 	get_device(chip->dev);
 
 	spin_unlock(&driver_lock);
 
 	chip->data_buffer = kmalloc(TPM_BUFSIZE * sizeof(u8), GFP_KERNEL);
 	if (chip->data_buffer == NULL) {
-		chip->num_opens--;
+		atomic_dec(&chip->num_opens);
 		put_device(chip->dev);
-		unlock_kernel();
 		return -ENOMEM;
 	}
 
 	atomic_set(&chip->data_pending, 0);
 
 	file->private_data = chip;
-	unlock_kernel();
 	return 0;
 
 err_out:
 	spin_unlock(&driver_lock);
-	unlock_kernel();
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm_open);

@@ -1016,7 +1012,7 @@ int tpm_release(struct inode *inode, struct file *file)
 	file->private_data = NULL;
 	del_singleshot_timer_sync(&chip->user_read_timer);
 	atomic_set(&chip->data_pending, 0);
-	chip->num_opens--;
+	atomic_dec(chip->num_opens);
 	put_device(chip->dev);
 	kfree(chip->data_buffer);
 	spin_unlock(&driver_lock);

@@ -1231,20 +1227,16 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
 		return NULL;
 	}
 
-	spin_lock(&driver_lock);
-
-	list_add(&chip->list, &tpm_chip_list);
-
-	spin_unlock(&driver_lock);
-
 	if (sysfs_create_group(&dev->kobj, chip->vendor.attr_group)) {
-		list_del(&chip->list);
 		misc_deregister(&chip->vendor.miscdev);
 		put_device(chip->dev);
 		return NULL;
 	}
 
 	chip->bios_dir = tpm_bios_log_setup(devname);
+	spin_lock(&driver_lock);
+	list_add(&chip->list, &tpm_chip_list);
+	spin_unlock(&driver_lock);
 
 	return chip;
 }

drivers/char/tpm/tpm.h +1 -1

index e885148..edb8ed6 100644
@@ -90,7 +90,7 @@ struct tpm_chip {
 	struct device *dev;	/* Device stuff */
 
 	int dev_num;		/* /dev/tpm# */
-	int num_opens;		/* only one allowed */
+	atomic_t num_opens;		/* only one allowed */
 	int time_expired;
 
 	/* Data passed to and from the tpm via the read/write calls */

Signature · 1 line

1.5.4.5

Quoted 4 lines · Rajiv Andrade

This patch removes the BKL calls from the TPM driver, which were added in the overall misc-char-dev-BKL-pushdown.patch, as they are not needed. Changed num_opens from an int to atomic_t.

Quoted 2 lines

Signed-off-by Mimi Zohar <[email protected]>

Signed-off-by Rajiv Andrade <[email protected]>

Yes, this patch is good.

It would also be good to rename num_opens. Note that it is always either 0 or 1, and indicates whether someone has opened the chip. So 'is_open' may make more sense.