[PATCH 11/25] tty: serial: lpc32xx_hs: drop uart_port->lock before calling tty_flip_buffer_push()

[Viresh Kumar <viresh.kumar@linaro.org>]

The -rt patch triggers a lockdep warning for serial drivers if
tty_flip_buffer_push() is called with uart_port->lock locked. This never shows
up on UP kernels.

Release the port lock before calling tty_flip_buffer_push() and reacquire it
after the call.

Similar stuff was already done for few other drivers in the past, like:

commit 2389b272168ceec056ca1d8a870a97fa9c26e11a
Author: Thomas Gleixner <tglx@linutronix.de>
Date:   Tue May 29 21:53:50 2007 +0100

    [ARM] 4417/1: Serial: Fix AMBA drivers locking

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/tty/serial/lpc32xx_hs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index 8fdf6a8..701644f 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -279,7 +279,10 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
 
 		tmp = readl(LPC32XX_HSUART_FIFO(port->membase));
 	}
+
+	spin_unlock(&port->lock);
 	tty_flip_buffer_push(tport);
+	spin_lock(&port->lock);
 }
 
 static void __serial_lpc32xx_tx(struct uart_port *port)
-- 
1.7.12.rc2.18.g61b472e