From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8CF8C33CB3 for ; Wed, 15 Jan 2020 12:36:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AFA2F2467C for ; Wed, 15 Jan 2020 12:36:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579091769; bh=Zn5YUWMjJaii5+Wh6/mMidWzdRlfpQDPnJUaF8RwJxg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=dkT3VrJNaMOwWiwS/p1Q+SYYzWw7eR3Z+ntRHWtFXOJegwXktx7UP2CgKGUcUMXGJ lKU/AcMQu0Wd0JOuazfoUfdZTu50sHuTjyxRN6MKd68+XUUF5rVq+3dV2yCF957ug5 dnXQ67I8la64L12bqO65fuaoyVdGhUf6KS3JT1pw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726474AbgAOMgF (ORCPT ); Wed, 15 Jan 2020 07:36:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:52760 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726071AbgAOMgF (ORCPT ); Wed, 15 Jan 2020 07:36:05 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BDB4724679; Wed, 15 Jan 2020 12:36:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579091764; bh=Zn5YUWMjJaii5+Wh6/mMidWzdRlfpQDPnJUaF8RwJxg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZnoFqM3ety8zk+QArvc+sqGentBLZikbuLuYiipxowNn2syZ3SHpXBEL2AJDvycQO ZMcELqqcBMDiJz25Ifu/ZxfYWc3a6Iz0gLZkUen6CT31zwuWzKO26SLq/soeClBnFE PBnEuTW2w/Ia7w8sOADXzeT/xgYsrshkv6RwFFBw= Date: Wed, 15 Jan 2020 13:36:01 +0100 From: Greg Kroah-Hartman To: Dmitry Safonov Cc: linux-kernel@vger.kernel.org, Dmitry Safonov <0x7f454c46@gmail.com>, Iurii Zaikin , Jiri Slaby , Joe Perches , Randy Dunlap , Vasiliy Khoruzhick , linux-serial@vger.kernel.org, Luis Chamberlain , Kees Cook , linux-fsdevel@vger.kernel.org Subject: Re: [PATCHv2-next 1/3] sysctl/sysrq: Remove __sysrq_enabled copy Message-ID: <20200115123601.GA3461986@kroah.com> References: <20200114171912.261787-1-dima@arista.com> <20200114171912.261787-2-dima@arista.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200114171912.261787-2-dima@arista.com> Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Tue, Jan 14, 2020 at 05:19:10PM +0000, Dmitry Safonov wrote: > Many embedded boards have a disconnected TTL level serial which can > generate some garbage that can lead to spurious false sysrq detects. > > Currently, sysrq can be either completely disabled for serial console > or always disabled (with CONFIG_MAGIC_SYSRQ_SERIAL), since > commit 732dbf3a6104 ("serial: do not accept sysrq characters via serial port") > > At Arista, we have such boards that can generate BREAK and random > garbage. While disabling sysrq for serial console would solve > the problem with spurious false sysrq triggers, it's also desirable > to have a way to enable sysrq back. > > Having the way to enable sysrq was beneficial to debug lockups with > a manual investigation in field and on the other side preventing false > sysrq detections. > > As a preparation to add sysrq_toggle_support() call into uart, > remove a private copy of sysrq_enabled from sysctl - it should reflect > the actual status of sysrq. > > Furthermore, the private copy isn't correct already in case > sysrq_always_enabled is true. So, remove __sysrq_enabled and use a > getter-helper for sysrq enabled status. > > Cc: Iurii Zaikin > Cc: Jiri Slaby > Cc: Luis Chamberlain > Cc: Kees Cook > Cc: linux-fsdevel@vger.kernel.org > Signed-off-by: Dmitry Safonov > --- > drivers/tty/sysrq.c | 7 +++++++ > include/linux/sysrq.h | 7 +++++++ > kernel/sysctl.c | 41 ++++++++++++++++++++++------------------- > 3 files changed, 36 insertions(+), 19 deletions(-) > > diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c > index f724962a5906..ef3e78967146 100644 > --- a/drivers/tty/sysrq.c > +++ b/drivers/tty/sysrq.c > @@ -73,6 +73,13 @@ static bool sysrq_on_mask(int mask) > (sysrq_enabled & mask); > } > > +int sysrq_get_mask(void) > +{ > + if (sysrq_always_enabled) > + return 1; > + return sysrq_enabled; > +} Naming is hard. And this name is really hard to understand. Traditionally get/put are used for incrementing reference counts. You don't have a sysrq_put_mask() call, right? :) I think what you want this function to do is, "is sysrq enabled right now" (hint, it's a global function, add kernel-doc to it so we know what it does...). If so, it should maybe be something like: bool sysrq_is_enabled(void); which to me makes more sense. thoughts? thanks, greg k-h