From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: [PATCH 03/25] tty: serial: apbuart: drop uart_port->lock before calling tty_flip_buffer_push() Date: Fri, 16 Aug 2013 17:13:04 +0530 Message-ID: <5eb096b77ce72ef4bc0c2ddc07b4518bca4b88c9.1376651114.git.viresh.kumar@linaro.org> References: Return-path: Received: from mail-pb0-f48.google.com ([209.85.160.48]:42095 "EHLO mail-pb0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755230Ab3HPLn4 (ORCPT ); Fri, 16 Aug 2013 07:43:56 -0400 Received: by mail-pb0-f48.google.com with SMTP id ma3so1884189pbc.7 for ; Fri, 16 Aug 2013 04:43:56 -0700 (PDT) In-Reply-To: In-Reply-To: References: Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: gregkh@linuxfoundation.org, jslaby@suse.cz Cc: linaro-kernel@lists.linaro.org, patches@linaro.org, linux-serial@vger.kernel.org, Viresh Kumar 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 Date: Tue May 29 21:53:50 2007 +0100 [ARM] 4417/1: Serial: Fix AMBA drivers locking Signed-off-by: Viresh Kumar --- drivers/tty/serial/apbuart.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/tty/serial/apbuart.c b/drivers/tty/serial/apbuart.c index 6331464d..de11ab8 100644 --- a/drivers/tty/serial/apbuart.c +++ b/drivers/tty/serial/apbuart.c @@ -125,7 +125,9 @@ static void apbuart_rx_chars(struct uart_port *port) status = UART_GET_STATUS(port); } + spin_unlock(&port->lock); tty_flip_buffer_push(&port->state->port); + spin_lock(&port->lock); } static void apbuart_tx_chars(struct uart_port *port) -- 1.7.12.rc2.18.g61b472e