linux-kernel - [PATCH 2/4] TPM: num_opens to is

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Date:	Tue, 23 Sep 2008 14:19:27 -0300
From:	Rajiv Andrade <srajiv@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, jmoriss@...ei.org,
	serue@...ux.vnet.ibm.com, zohar@...ux.vnet.ibm.com,
	safford@...son.ibm.com, paulmck@...ux.vnet.ibm.com,
	debora@...ux.vnet.ibm.com
Subject: [PATCH 2/4] TPM: num_opens to is_open variable change

Renames num_open to is_open, as only one process can open the file at a time.

Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@...ux.vnet.ibm.com>
---
 drivers/char/tpm/tpm.c |    7 +++----
 drivers/char/tpm/tpm.h |    2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index ceba608..dfd4e7f 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -978,20 +978,19 @@ int tpm_open(struct inode *inode, struct file *file)
 		goto err_out;
 	}
 
-	if (chip->num_opens) {
+	if (test_and_set_bit(0, &chip->is_open)) {
 		dev_dbg(chip->dev, "Another process owns this TPM\n");
 		rc = -EBUSY;
 		goto err_out;
 	}
 
-	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--;
+		clear_bit(0, &chip->is_open);
 		put_device(chip->dev);
 		return -ENOMEM;
 	}
@@ -1016,7 +1015,7 @@ 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--;
+	clear_bit(0, &chip->is_open);
 	put_device(chip->dev);
 	kfree(chip->data_buffer);
 	spin_unlock(&driver_lock);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index e885148..2756cab 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -90,7 +90,7 @@ struct tpm_chip {
 	struct device *dev;	/* Device stuff */
 
 	int dev_num;		/* /dev/tpm# */
-	int num_opens;		/* only one allowed */
+	unsigned long is_open;	/* only one allowed */
 	int time_expired;
 
 	/* Data passed to and from the tpm via the read/write calls */
-- 
1.5.6.3

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