On 6/12/18 10:58 AM, Tadeusz Struk wrote:
Currently the TPM driver only supports blocking calls, which doesn't allow
asynchronous IO operations to the TPM hardware.
This patch changes it and adds support for nonblocking write and a new poll
function to enable applications, which want to take advantage of this.
Signed-off-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxx>
---
snip
.
.
.
@@ -84,10 +124,9 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
size_t size, loff_t *off)
{
struct file_priv *priv = file->private_data;
- size_t in_size = size;
- ssize_t out_size;
+ int ret = 0;
- if (in_size > TPM_BUFSIZE)
+ if (size > TPM_BUFSIZE)
return -E2BIG;
mutex_lock(&priv->buffer_mutex);
@@ -97,20 +136,19 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
* buffered writes from blocking here.
*/
if (priv->data_pending != 0) {
- mutex_unlock(&priv->buffer_mutex);
- return -EBUSY;
+ ret = -EBUSY;
+ goto out;
}
- if (copy_from_user
- (priv->data_buffer, (void __user *) buf, in_size)) {
- mutex_unlock(&priv->buffer_mutex);
- return -EFAULT;
+ if (copy_from_user(priv->data_buffer, buf, size)) {
+ ret = -EFAULT;
+ goto out;
}
- if (in_size < 6 ||
- in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) {
- mutex_unlock(&priv->buffer_mutex);
- return -EINVAL;
+ if (size < 6 ||
+ size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) {
+ ret = -EINVAL;
+ goto out;
}
/* atomic tpm command send and result receive. We only hold the ops
@@ -118,25 +156,48 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
* the char dev is held open.
*/
if (tpm_try_get_ops(priv->chip)) {
- mutex_unlock(&priv->buffer_mutex);
- return -EPIPE;
+ ret = -EPIPE;
+ goto out;
}
- out_size = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
- sizeof(priv->data_buffer), 0);
- tpm_put_ops(priv->chip);
- if (out_size < 0) {
- mutex_unlock(&priv->buffer_mutex);
- return out_size;
+ /*
+ * If in nonblocking mode schedule an async job to send
+ * the command return the size.
+ * In case of error the err code will be returned in
+ * the subsequent read call.
+ */
+ if (file->f_flags & O_NONBLOCK) {
+ queue_work(tpm_dev_wq, &priv->async_work);
+ return size;
Apologies for the question, but should there be a mutex_unlock() here?
It's about the only return statement I am seeing where I cannot tell if
a mutex_unlock() will be called before return or is needed before
return. The rest of the code is pretty obvious the return statements
are being re-factored to an out: block where the mutex_unlock() will
always be called before returning.
Thanks,
Jay
