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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 A5FA1C3404D for ; Wed, 19 Feb 2020 11:03:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91490206DB for ; Wed, 19 Feb 2020 11:03:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726820AbgBSLDQ (ORCPT ); Wed, 19 Feb 2020 06:03:16 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:59127 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726779AbgBSLDQ (ORCPT ); Wed, 19 Feb 2020 06:03:16 -0500 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1j4N8H-0004mY-1p; Wed, 19 Feb 2020 12:03:09 +0100 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1j4N8E-0001EF-SZ; Wed, 19 Feb 2020 12:03:06 +0100 Date: Wed, 19 Feb 2020 12:03:06 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Johan Hovold Cc: Jacek Anaszewski , Pavel Machek , Dan Murphy , Greg Kroah-Hartman , Jiri Slaby , linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de, linux-serial@vger.kernel.org Subject: Re: [PATCH v6 4/4] leds: trigger: implement a tty trigger Message-ID: <20200219110306.k5jndutalll64esu@pengutronix.de> References: <20200213091600.554-1-uwe@kleine-koenig.org> <20200213091600.554-5-uwe@kleine-koenig.org> <20200219105239.GA32540@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200219105239.GA32540@localhost> User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-serial@vger.kernel.org Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Wed, Feb 19, 2020 at 11:52:39AM +0100, Johan Hovold wrote: > On Thu, Feb 13, 2020 at 10:16:00AM +0100, Uwe Kleine-König wrote: > > From: Uwe Kleine-König > > > > Usage is as follows: > > > > myled=ledname > > tty=ttyS0 > > > > echo tty > /sys/class/leds/$myled/trigger > > cat /sys/class/tty/$tty/dev > /sys/class/leds/$myled/dev > > > > . When this new trigger is active it periodically checks the tty's > > statistics and when it changed since the last check the led is flashed > > once. > > > > Signed-off-by: Uwe Kleine-König > > --- > > > +static ssize_t dev_store(struct device *dev, > > + struct device_attribute *attr, const char *buf, > > + size_t size) > > +{ > > + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev); > > + struct tty_struct *tty; > > + dev_t d; > > + int ret; > > + > > + if (size == 0 || (size == 1 && buf[0] == '\n')) { > > + tty = NULL; > > + } else { > > + ret = kstrtodev_t(buf, &d); > > + if (ret < 0) > > + return ret; > > + > > + tty = tty_kopen_shared(d); > > I really don't have time to look at this, but having the led-trigger > keep the port open looks fundamentally broken (consider modem-control > signals, power, etc). If I understand correctly calling tty_kopen_shared() doesn't open the device, just keep it referenced which prevents it to disappear. Unless I miss something it doesn't result in the tty's .open() being called. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |