On 2018-07-13 10:33:54 [+0200], Esben Haabendal wrote:

But is the lock ordering in tty_buffer_flush() really needed?
Could we move the

	if (ld && ld->ops->flush_buffer)
		ld->ops->flush_buffer(tty);

lines out of the &buf->lock section?  I don't think that any code
outside of tty_buffer.c should touch the port->buf code, and thus should
not need to hold the &buf->lock.

You could try this out and see what happens. If you attempt to change
the locking then I suggest you involve upstream. I haven't looked too
closely into it. I remember Peter wasn't too happy about the locking
while the "low latency" shortcut was in and then he removed it.

/Esben

Sebastian