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 Signed-off-by: Johan Hovold johan@kernel.org --- drivers/usb/serial/keyspan_pda.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c index 2d5ad579475a..17b60e5a9f1f 100644 --- a/drivers/usb/serial/keyspan_pda.c +++ b/drivers/usb/serial/keyspan_pda.c @@ -443,6 +443,7 @@ static int keyspan_pda_write(struct tty_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 @@ -462,13 +463,13 @@ static int keyspan_pda_write(struct tty_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