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-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c01d2c58698f710c9e13ba3e2d296328606f74fd;p=linux.git

USB: serial: keyspan_pda: fix stalled writes

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>
---

diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index 17b60e5a9f1fe..d6ebde779e854 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -548,7 +548,7 @@ 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;
 }