Commit a7216fd9 authored Oct 25, 2020 by Johan Hovold Committed by Greg Kroah-Hartman Dec 30, 2020

USB: serial: keyspan_pda: fix dropped unthrottle interrupts



commit 696c541c8c6cfa05d65aa24ae2b9e720fc01766e upstream.

Commit c528fcb1 ("USB: serial: keyspan_pda: fix receive sanity
checks") broke write-unthrottle handling by dropping well-formed
unthrottle-interrupt packets which are precisely two bytes long. This
could lead to blocked writers not being woken up when buffer space again
becomes available.

Instead, stop unconditionally printing the third byte which is
(presumably) only valid on modem-line changes.

Fixes: c528fcb1 ("USB: serial: keyspan_pda: fix receive sanity checks")
Cc: stable <stable@vger.kernel.org>     # 4.11
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 88dd1bcb

drivers/usb/serial/keyspan_pda.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -172,11 +172,11 @@ static void keyspan_pda_rx_interrupt(struct urb *urb)
		break;
		case 1:
		/* status interrupt */
		if (len < 3) {
		if (len < 2) {
		dev_warn(&port->dev, "short interrupt message received\n");
		break;
		}
		dev_dbg(&port->dev, "rx int, d1=%d, d2=%d\n", data[1], data[2]);
		dev_dbg(&port->dev, "rx int, d1=%d\n", data[1]);
		switch (data[1]) {
		case 1: /* modemline change */
		break;