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Subject[PATCH 3/3] TPM: data_pending is no longer atomic
Date
Now that data_pending is fully protected by a mutex, it no longer
needs to be atomic.

Reported-by: Seth Forshee <seth.forshee@canonical.com>
Cc: Debora Velarde <debora@linux.vnet.ibm.com>
Cc: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Cc: Marcel Selhorst <m.selhorst@sirrix.com>
Cc: tpmdd-devel@lists.sourceforge.net
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
drivers/char/tpm/tpm.c | 16 ++++++++--------
drivers/char/tpm/tpm.h | 2 +-
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 70bf9e5..6ac164f 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -342,7 +342,7 @@ static void timeout_work(struct work_struct *work)
struct tpm_chip *chip = container_of(work, struct tpm_chip, work);

mutex_lock(&chip->buffer_mutex);
- atomic_set(&chip->data_pending, 0);
+ chip->data_pending = 0;
memset(chip->data_buffer, 0, TPM_BUFSIZE);
mutex_unlock(&chip->buffer_mutex);
}
@@ -1043,7 +1043,7 @@ int tpm_open(struct inode *inode, struct file *file)
return -ENOMEM;
}

- atomic_set(&chip->data_pending, 0);
+ chip->data_pending = 0;

file->private_data = chip;
return 0;
@@ -1060,7 +1060,7 @@ int tpm_release(struct inode *inode, struct file *file)
del_singleshot_timer_sync(&chip->user_read_timer);
flush_work_sync(&chip->work);
file->private_data = NULL;
- atomic_set(&chip->data_pending, 0);
+ chip->data_pending = 0;
kfree(chip->data_buffer);
clear_bit(0, &chip->is_open);
put_device(chip->dev);
@@ -1078,7 +1078,7 @@ ssize_t tpm_write(struct file *file, const char __user *buf,

/* cannot perform a write until the read has cleared
either via tpm_read or a user_read_timer timeout */
- while (atomic_read(&chip->data_pending) != 0) {
+ while (chip->data_pending != 0) {
mutex_unlock(&chip->buffer_mutex);
msleep(TPM_TIMEOUT);
mutex_lock(&chip->buffer_mutex);
@@ -1096,7 +1096,7 @@ ssize_t tpm_write(struct file *file, const char __user *buf,
/* atomic tpm command send and result receive */
out_size = tpm_transmit(chip, chip->data_buffer, TPM_BUFSIZE);

- atomic_set(&chip->data_pending, out_size);
+ chip->data_pending = out_size;
mutex_unlock(&chip->buffer_mutex);

/* Set a timeout by which the reader must come claim the result */
@@ -1116,18 +1116,18 @@ ssize_t tpm_read(struct file *file, char __user *buf,
del_singleshot_timer_sync(&chip->user_read_timer);
flush_work_sync(&chip->work);
mutex_lock(&chip->buffer_mutex);
- ret_size = atomic_xchg(&chip->data_pending, 0);
+ ret_size = chip->data_pending;
if (ret_size > 0) { /* relay data */
- ssize_t orig_ret_size = ret_size;
if (size < ret_size)
ret_size = size;

rc = copy_to_user(buf, chip->data_buffer, ret_size);
- memset(chip->data_buffer, 0, orig_ret_size);
+ memset(chip->data_buffer, 0, chip->data_pending);
if (rc)
ret_size = -EFAULT;
}

+ chip->data_pending = 0;
mutex_unlock(&chip->buffer_mutex);
return ret_size;
}
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 9c4163c..6ee8064 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -103,7 +103,7 @@ struct tpm_chip {

/* Data passed to and from the tpm via the read/write calls */
u8 *data_buffer;
- atomic_t data_pending;
+ size_t data_pending;
struct mutex buffer_mutex;

struct timer_list user_read_timer; /* user needs to claim result */
--
1.7.0.4


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