IB/mlx5: Implement the file ops of DEVX async command FD

Implement the file ops of the DEVX async command FD, this enables using
the FD for reading the events and manage other options on the FD.
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/devx.c

@@ -1472,7 +1472,49 @@ static int devx_umem_cleanup(struct ib_uobject *uobject,
 static ssize_t devx_async_cmd_event_read(struct file *filp, char __user *buf,
 					 size_t count, loff_t *pos)
 {
-	return -EINVAL;
+	struct devx_async_cmd_event_file *comp_ev_file = filp->private_data;
+	struct devx_async_event_queue *ev_queue = &comp_ev_file->ev_queue;
+	struct devx_async_data *event;
+	int ret = 0;
+	size_t eventsz;
+
+	spin_lock_irq(&ev_queue->lock);
+
+	while (list_empty(&ev_queue->event_list)) {
+		spin_unlock_irq(&ev_queue->lock);
+
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		if (wait_event_interruptible(
+			    ev_queue->poll_wait,
+			    !list_empty(&ev_queue->event_list))) {
+			return -ERESTARTSYS;
+		}
+		spin_lock_irq(&ev_queue->lock);
+	}
+
+	event = list_entry(ev_queue->event_list.next,
+			   struct devx_async_data, list);
+	eventsz = event->cmd_out_len +
+			sizeof(struct mlx5_ib_uapi_devx_async_cmd_hdr);
+
+	if (eventsz > count) {
+		spin_unlock_irq(&ev_queue->lock);
+		return -ENOSPC;
+	}
+
+	list_del(ev_queue->event_list.next);
+	spin_unlock_irq(&ev_queue->lock);
+
+	if (copy_to_user(buf, &event->hdr, eventsz))
+		ret = -EFAULT;
+	else
+		ret = eventsz;
+
+	atomic_sub(event->cmd_out_len, &ev_queue->bytes_in_use);
+	kvfree(event);
+	return ret;
 }
 
 static int devx_async_cmd_event_close(struct inode *inode, struct file *filp)
@@ -1495,7 +1537,18 @@ static int devx_async_cmd_event_close(struct inode *inode, struct file *filp)
 static __poll_t devx_async_cmd_event_poll(struct file *filp,
 					      struct poll_table_struct *wait)
 {
-	return 0;
+	struct devx_async_cmd_event_file *comp_ev_file = filp->private_data;
+	struct devx_async_event_queue *ev_queue = &comp_ev_file->ev_queue;
+	__poll_t pollflags = 0;
+
+	poll_wait(filp, &ev_queue->poll_wait, wait);
+
+	spin_lock_irq(&ev_queue->lock);
+	if (!list_empty(&ev_queue->event_list))
+		pollflags = EPOLLIN | EPOLLRDNORM;
+	spin_unlock_irq(&ev_queue->lock);
+
+	return pollflags;
 }
 
 const struct file_operations devx_async_cmd_event_fops = {