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=-12.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 0F4C5C47420 for ; Tue, 29 Sep 2020 16:23:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AFFF220936 for ; Tue, 29 Sep 2020 16:23:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601396623; bh=LdBtfC8GVlPycb+DDCNGugGOm5JDifRZwYM4+DBP2e0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=PwLrC+TMYC63IN25zsxf8wbeQ50Ah8R52iW6cBjRgiUcPyW3GfLu34IZQt8lw6N/Q aVBPvm4QoFYfk9cMLUjV+1dlFE0FAFzVg3kxmkjcRL1Ks9bk1F00afNGj1HfiTJvz6 59bkC8FvyswDlc/mXDlrw0UKbhyDKN8mbzBzUOdI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728958AbgI2QXm (ORCPT ); Tue, 29 Sep 2020 12:23:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:34492 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728184AbgI2QXl (ORCPT ); Tue, 29 Sep 2020 12:23:41 -0400 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (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 1067221548; Tue, 29 Sep 2020 16:23:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601396621; bh=LdBtfC8GVlPycb+DDCNGugGOm5JDifRZwYM4+DBP2e0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=jPmf6qMM4ipXwBDXsHWqITED0ALNcz2r4jdOLCCVF7Vq7i8rWAMYW4h2Fspkh23lz EYbGpB6gDcm11gTYA32RwlHkV50WWO2KdeAxrD+GbLF25ZDKsETV2i7BcLo/+4CDUu i2OfE7Kda+TOGn1PZCS9ywrra2r3jmISuX81fDQw= Date: Tue, 29 Sep 2020 17:23:29 +0100 From: Jonathan Cameron To: Mircea Caprioru Cc: , , , , , , Sergiu Cuciurean Subject: Re: [PATCH 5/5] iio: adc: rockchip_saradc: Replace indio_dev->mlock with own device lock Message-ID: <20200929172329.778ab2c6@archlinux> In-Reply-To: <20200928131333.36646-5-mircea.caprioru@analog.com> References: <20200928131333.36646-1-mircea.caprioru@analog.com> <20200928131333.36646-5-mircea.caprioru@analog.com> X-Mailer: Claws Mail 3.17.6 (GTK+ 2.24.32; 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-kernel@vger.kernel.org On Mon, 28 Sep 2020 16:13:33 +0300 Mircea Caprioru wrote: > From: Sergiu Cuciurean > > As part of the general cleanup of indio_dev->mlock, this change replaces > it with a local lock on the device's state structure. > > This is part of a bigger cleanup. > Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/ > > Signed-off-by: Sergiu Cuciurean > Signed-off-by: Mircea Caprioru Another driver with buffered support which means we need to think harder about what is going on with these locks. > --- > drivers/iio/adc/rockchip_saradc.c | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-) > > diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c > index 1f3d7d639d37..80084c526cc6 100644 > --- a/drivers/iio/adc/rockchip_saradc.c > +++ b/drivers/iio/adc/rockchip_saradc.c > @@ -53,6 +53,15 @@ struct rockchip_saradc { > const struct rockchip_saradc_data *data; > u16 last_val; > const struct iio_chan_spec *last_chan; > + /* > + * Lock to protect the device state during a potential concurrent > + * read access from userspace. Reading a raw value requires a sequence > + * of register writes, then a wait for a completion callback, > + * and finally a register read, during which userspace could issue > + * another read request. This lock protects a read access from > + * ocurring before another one has finished. > + */ > + struct mutex lock; > }; > > static void rockchip_saradc_power_down(struct rockchip_saradc *info) > @@ -92,17 +101,17 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev, > > switch (mask) { > case IIO_CHAN_INFO_RAW: > - mutex_lock(&indio_dev->mlock); > + mutex_lock(&info->lock); Probably a case for iio_device_claim_direct_mode() as I doubt we want to enter buffered mode when halfway through this. > > ret = rockchip_saradc_conversion(info, chan); > if (ret) { > rockchip_saradc_power_down(info); > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&info->lock); > return ret; > } > > *val = info->last_val; > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&info->lock); > return IIO_VAL_INT; > case IIO_CHAN_INFO_SCALE: > ret = regulator_get_voltage(info->vref); > @@ -254,7 +263,7 @@ static irqreturn_t rockchip_saradc_trigger_handler(int irq, void *p) > int ret; > int i, j = 0; > > - mutex_lock(&i_dev->mlock); > + mutex_lock(&info->lock); Hmm. I wonder what this was meant to protect? I can't see why we need it if we are claiming direct mode correctly above. > > for_each_set_bit(i, i_dev->active_scan_mask, i_dev->masklength) { > const struct iio_chan_spec *chan = &i_dev->channels[i]; > @@ -271,7 +280,7 @@ static irqreturn_t rockchip_saradc_trigger_handler(int irq, void *p) > > iio_push_to_buffers_with_timestamp(i_dev, &data, iio_get_time_ns(i_dev)); > out: > - mutex_unlock(&i_dev->mlock); > + mutex_unlock(&info->lock); > > iio_trigger_notify_done(i_dev->trig); > > @@ -332,6 +341,8 @@ static int rockchip_saradc_probe(struct platform_device *pdev) > info->reset = NULL; > } > > + mutex_init(&info->lock); > + > init_completion(&info->completion); > > irq = platform_get_irq(pdev, 0);