From: Johan Hovold <johan@kernel.org>
Date: Sun, 25 Oct 2020 17:45:49 +0000 (+0100)
Subject: USB: serial: keyspan_pda: fix stalled writes
X-Git-Tag: v4.4.249~22
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fc9c541454729c30c7169c04a305be46252ab46b;p=thirdparty%2Fkernel%2Fstable.git

USB: serial: keyspan_pda: fix stalled writes

commit c01d2c58698f710c9e13ba3e2d296328606f74fd upstream.

Make sure to clear the write-busy flag also in case no new data was
submitted due to lack of device buffer space so that writing is
resumed once space again becomes available.

Fixes: 507ca9bc0476 ("[PATCH] USB: add ability for usb-serial drivers to determine if their write urb is currently being used.")
Cc: stable <stable@vger.kernel.org>     # 2.6.13
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>
---

diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index 6e09ce63d2e64..ac649431be2fb 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -552,7 +552,7 @@ static int keyspan_pda_write(struct tty_struct *tty,
 
 	rc = count;
 exit:
-	if (rc < 0)
+	if (rc <= 0)
 		set_bit(0, &port->write_urbs_free);
 	return rc;
 }