Hi David, On Mon, Jul 07, 2014 at 09:13:53AM +0000, David Laight wrote: > From: Olivier Sobrie > > When the module sends bursts of data, sometimes a deadlock happens in > > the hso driver when the tty buffer doesn't get the chance to be flushed > > quickly enough. > > > > To avoid this, first, we remove the endless while loop in > > put_rx_bufdata() which is the root cause of the deadlock. > > Secondly, when there is no room anymore in the tty buffer, we set up a > > timer of 100 msecs to give a chance to the upper layer to flush the tty > > buffer and make room for new data. > > What is the timer for? > You need to get the sending code woken up by the urb completion. In put_rxbuf_data() (which can be called under irq disabled), tty_flip_buffer_push() is called and schedules a push of the tty buffer. When the buffer is full, I give some time to the above layer in order to flush it. The timer is used to recall put_rxbuf_data_and_resubmit_bulk_urb() later in order to read the remaining data stored in "urb->transfer_buffer" and then to resubmit the urb to receive more data from the gsm module. I don't understand what you mean by "getting the sending code woken up". Calling tty_port_tty_wakeup()?? We are in the receive path... Thanks, -- Olivier -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
