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USB: serial: keyspan_pda: fix dropped unthrottle interrupts 

commit 696c541c8c upstream.

Commit c528fcb116 ("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: c528fcb116 ("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>
5.4-rM2-2.2.x-imx-squashed
Johan Hovold 2020-10-25 18:45:47 +01:00 committed by Greg Kroah-Hartman
parent 89fb2b91a9
commit ebd9857a5b
1 changed files with 2 additions and 2 deletions
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4
drivers/usb/serial/keyspan_pda.c
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@ -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;