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=-15.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham 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 228AEC433E0 for ; Wed, 30 Dec 2020 12:09:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7FF720757 for ; Wed, 30 Dec 2020 12:09:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726612AbgL3MJg (ORCPT ); Wed, 30 Dec 2020 07:09:36 -0500 Received: from mail.kernel.org ([198.145.29.99]:45374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726536AbgL3MJg (ORCPT ); Wed, 30 Dec 2020 07:09:36 -0500 Received: from archlinux (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (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 0B17F20757; Wed, 30 Dec 2020 12:08:53 +0000 (UTC) Date: Wed, 30 Dec 2020 12:08:50 +0000 From: Jonathan Cameron To: Lorenzo Bianconi Cc: Lorenzo Bianconi , linux-iio@vger.kernel.org, Linus Walleij , Denis CIOCCA Subject: Re: [PATCH v3] iio: common: st_sensors: fix possible infinite loop in st_sensors_irq_thread Message-ID: <20201230120850.6dd32cfc@archlinux> In-Reply-To: References: <20201213150447.119eec7c@archlinux> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Tue, 22 Dec 2020 11:53:57 +0100 Lorenzo Bianconi wrote: > > > > > > > > On Tue, 8 Dec 2020 15:36:40 +0100 > > > Lorenzo Bianconi wrote: > > > > > > > Return a boolean value in st_sensors_new_samples_available routine in > > > > order to avoid an infinite loop in st_sensors_irq_thread if > > > > stat_drdy.addr is not defined or stat_drdy read fails > > > > > > > > Fixes: 90efe05562921 ("iio: st_sensors: harden interrupt handling") > > > > Reported-by: Jonathan Cameron > > > > Reviewed-by: Linus Walleij > > > > Signed-off-by: Lorenzo Bianconi > > > > > > One trivial inline. Note I'm looking for an Ack form Dennis on this one > > > as it may result in a some breakage if any devices are using > > > edge interrupts. > > > > Looking at the current code I am wondering if it is possible since we > > would have already triggered the infinite loop in this case. I think > > nobody is currently using edge interrupts if the status register is > > not available. What do you think? > > > > Hi Jonathan, > > any news about this patch? > > Regards, > Lorenzo It's a very minor gamble, so I've applied it to the fixes-togreg branch of iio.git. Fingers crossed no one hits the corner case and has somehow been getting away with it. Thanks, Jonathan > > > Regards, > > Lorenzo > > > > > > > > It's possible we would be better falling back to interrupt free support > > > in that case rather than failing to probe at all. > > > I think that would be best done by moving the check out to the > > > various per type drivers so we fail in the same fashion as no irq > > > provided + a warning. > > > > > > > > > > thanks, > > > > > > Jonathan > > > > > > > > > > --- > > > > Changes since v2: > > > > - return -EOPNOTSUPP if the drv requests edge IRQ and the sensor does not support > > > > status register > > > > > > > > Changes since v1: > > > > - return true if the sensor does not have stat_drdy register > > > > --- > > > > .../common/st_sensors/st_sensors_trigger.c | 31 ++++++++++--------- > > > > 1 file changed, 17 insertions(+), 14 deletions(-) > > > > > > > > diff --git a/drivers/iio/common/st_sensors/st_sensors_trigger.c b/drivers/iio/common/st_sensors/st_sensors_trigger.c > > > > index 0507283bd4c1..2dbd2646e44e 100644 > > > > --- a/drivers/iio/common/st_sensors/st_sensors_trigger.c > > > > +++ b/drivers/iio/common/st_sensors/st_sensors_trigger.c > > > > @@ -23,35 +23,31 @@ > > > > * @sdata: Sensor data. > > > > * > > > > * returns: > > > > - * 0 - no new samples available > > > > - * 1 - new samples available > > > > - * negative - error or unknown > > > > + * false - no new samples available or read error > > > > + * true - new samples available > > > > */ > > > > -static int st_sensors_new_samples_available(struct iio_dev *indio_dev, > > > > - struct st_sensor_data *sdata) > > > > +static bool st_sensors_new_samples_available(struct iio_dev *indio_dev, > > > > + struct st_sensor_data *sdata) > > > > { > > > > int ret, status; > > > > > > > > /* How would I know if I can't check it? */ > > > > if (!sdata->sensor_settings->drdy_irq.stat_drdy.addr) > > > > - return -EINVAL; > > > > + return true; > > > > > > > > /* No scan mask, no interrupt */ > > > > if (!indio_dev->active_scan_mask) > > > > - return 0; > > > > + return false; > > > > > > > > ret = regmap_read(sdata->regmap, > > > > sdata->sensor_settings->drdy_irq.stat_drdy.addr, > > > > &status); > > > > if (ret < 0) { > > > > dev_err(sdata->dev, "error checking samples available\n"); > > > > - return ret; > > > > + return false; > > > > } > > > > > > > > - if (status & sdata->sensor_settings->drdy_irq.stat_drdy.mask) > > > > - return 1; > > > > - > > > > - return 0; > > > > + return !!(status & sdata->sensor_settings->drdy_irq.stat_drdy.mask); > > > > > > No need for the !! as you can rely on type conversion to a boolean. > > > > > > > } > > > > > > > > /** > > > > @@ -180,9 +176,15 @@ int st_sensors_allocate_trigger(struct iio_dev *indio_dev, > > > > > > > > /* Tell the interrupt handler that we're dealing with edges */ > > > > if (irq_trig == IRQF_TRIGGER_FALLING || > > > > - irq_trig == IRQF_TRIGGER_RISING) > > > > + irq_trig == IRQF_TRIGGER_RISING) { > > > > + if (!sdata->sensor_settings->drdy_irq.stat_drdy.addr) { > > > > + dev_err(&indio_dev->dev, > > > > + "edge IRQ not supported w/o stat register.\n"); > > > > + err = -EOPNOTSUPP; > > > > + goto iio_trigger_free; > > > > + } > > > > sdata->edge_irq = true; > > > > - else > > > > + } else { > > > > /* > > > > * If we're not using edges (i.e. level interrupts) we > > > > * just mask off the IRQ, handle one interrupt, then > > > > @@ -190,6 +192,7 @@ int st_sensors_allocate_trigger(struct iio_dev *indio_dev, > > > > * interrupt handler top half again and start over. > > > > */ > > > > irq_trig |= IRQF_ONESHOT; > > > > + } > > > > > > > > /* > > > > * If the interrupt pin is Open Drain, by definition this > > > >