On Tue, 2019-03-12 at 15:42 -0700, Tadeusz Struk wrote: > @@ -202,13 +196,15 @@ __poll_t tpm_common_poll(struct file *file, > poll_table *wait) > struct file_priv *priv = file->private_data; > __poll_t mask = 0; > > + mutex_lock(&priv->buffer_mutex); > poll_wait(file, &priv->async_wait, wait); > > - if (!priv->response_read || priv->response_length) > + if (priv->response_length) > mask = EPOLLIN | EPOLLRDNORM; > else > mask = EPOLLOUT | EPOLLWRNORM; > > + mutex_unlock(&priv->buffer_mutex); Isn't this setting us up for a deadlock? If the work queued by write hasn't run by the time you call poll, you take the buffer mutex and sleep. Now if the work runs, it blocks acquiring the mutex in tpm_async_work and never calls wakeup on async_wait. James
