| From 7353cad7ee4deaefc16e94727e69285563e219f6 Mon Sep 17 00:00:00 2001 |
| From: Johan Hovold <johan@kernel.org> |
| Date: Sun, 25 Oct 2020 18:45:48 +0100 |
| Subject: USB: serial: keyspan_pda: fix write deadlock |
| |
| From: Johan Hovold <johan@kernel.org> |
| |
| commit 7353cad7ee4deaefc16e94727e69285563e219f6 upstream. |
| |
| The write() callback can be called in interrupt context (e.g. when used |
| as a console) so interrupts must be disabled while holding the port lock |
| to prevent a possible deadlock. |
| |
| Fixes: e81ee637e4ae ("usb-serial: possible irq lock inversion (PPP vs. usb/serial)") |
| 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> # 2.6.19 |
| 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> |
| |
| --- |
| drivers/usb/serial/keyspan_pda.c | 7 ++++--- |
| 1 file changed, 4 insertions(+), 3 deletions(-) |
| |
| --- a/drivers/usb/serial/keyspan_pda.c |
| +++ b/drivers/usb/serial/keyspan_pda.c |
| @@ -447,6 +447,7 @@ static int keyspan_pda_write(struct tty_ |
| int request_unthrottle = 0; |
| int rc = 0; |
| struct keyspan_pda_private *priv; |
| + unsigned long flags; |
| |
| priv = usb_get_serial_port_data(port); |
| /* guess how much room is left in the device's ring buffer, and if we |
| @@ -466,13 +467,13 @@ static int keyspan_pda_write(struct tty_ |
| the TX urb is in-flight (wait until it completes) |
| the device is full (wait until it says there is room) |
| */ |
| - spin_lock_bh(&port->lock); |
| + spin_lock_irqsave(&port->lock, flags); |
| if (!test_bit(0, &port->write_urbs_free) || priv->tx_throttled) { |
| - spin_unlock_bh(&port->lock); |
| + spin_unlock_irqrestore(&port->lock, flags); |
| return 0; |
| } |
| clear_bit(0, &port->write_urbs_free); |
| - spin_unlock_bh(&port->lock); |
| + spin_unlock_irqrestore(&port->lock, flags); |
| |
| /* At this point the URB is in our control, nobody else can submit it |
| again (the only sudden transition was the one from EINPROGRESS to |
