From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755428AbaIBWMK (ORCPT ); Tue, 2 Sep 2014 18:12:10 -0400 Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:47549 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754581AbaIBWMF (ORCPT ); Tue, 2 Sep 2014 18:12:05 -0400 From: Peter Hurley To: Greg Kroah-Hartman Cc: Jiri Slaby , One Thousand Gnomes , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Hurley Subject: [PATCH 21/26] tty: Convert tty_struct bitfield to bools Date: Tue, 2 Sep 2014 17:39:30 -0400 Message-Id: <1409693975-1028-22-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1409693975-1028-1-git-send-email-peter@hurleysoftware.com> References: <1409693975-1028-1-git-send-email-peter@hurleysoftware.com> X-Authenticated-User: 990527 peter@hurleysoftware.com X-MT-ID: 8FA290C2A27252AACF65DBC4A42F3CE3735FB2A4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The stopped, hw_stopped, flow_stopped and packet bits are smp-unsafe and interrupt-unsafe. For example, CPU 0 | CPU 1 | tty->flow_stopped = 1 | tty->hw_stopped = 0 One of these updates will be corrupted, as the bitwise operation on the bitfield is non-atomic. Ensure each flag has a separate memory location, so concurrent updates do not corrupt orthogonal states. Signed-off-by: Peter Hurley --- include/linux/tty.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/tty.h b/include/linux/tty.h index 1c3316a..7cf61cb 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -261,7 +261,10 @@ struct tty_struct { unsigned long flags; int count; struct winsize winsize; /* winsize_mutex */ - unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1; + bool stopped; + bool hw_stopped; + bool flow_stopped; + bool packet; unsigned char ctrl_status; /* ctrl_lock */ unsigned int receive_room; /* Bytes free for queue */ int flow_change; -- 2.1.0