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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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