From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: [PATCH 05/25] tty: serial: arc: drop uart_port->lock before calling tty_flip_buffer_push() Date: Fri, 16 Aug 2013 17:13:06 +0530 Message-ID: <7af55e73a82958b94e65c8bd275aaa7eb7b88068.1376651114.git.viresh.kumar@linaro.org> References: Return-path: Received: from mail-pb0-f48.google.com ([209.85.160.48]:49828 "EHLO mail-pb0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755284Ab3HPLoJ (ORCPT ); Fri, 16 Aug 2013 07:44:09 -0400 Received: by mail-pb0-f48.google.com with SMTP id ma3so1884338pbc.7 for ; Fri, 16 Aug 2013 04:44:09 -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/arc_uart.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c index 22f280a..8cf6b30 100644 --- a/drivers/tty/serial/arc_uart.c +++ b/drivers/tty/serial/arc_uart.c @@ -248,7 +248,9 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart) uart_insert_char(&uart->port, status, RXOERR, ch, flg); done: + spin_unlock(&uart->port.lock); tty_flip_buffer_push(&uart->port.state->port); + spin_lock(&uart->port.lock); } } -- 1.7.12.rc2.18.g61b472e