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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 B361AC10DCE for ; Sun, 15 Mar 2020 14:15:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 97799205C9 for ; Sun, 15 Mar 2020 14:15:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728749AbgCOOP6 (ORCPT ); Sun, 15 Mar 2020 10:15:58 -0400 Received: from saturn.retrosnub.co.uk ([46.235.226.198]:53810 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727778AbgCOOP6 (ORCPT ); Sun, 15 Mar 2020 10:15:58 -0400 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) by saturn.retrosnub.co.uk (Postfix; Retrosnub mail submission) with ESMTPSA id 13E439E77F2; Sun, 15 Mar 2020 14:15:55 +0000 (GMT) Date: Sun, 15 Mar 2020 14:15:53 +0000 From: Jonathan Cameron To: Rohit Sarkar Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5] iio: adc: max1363: replace uses of mlock Message-ID: <20200315141553.3efc968c@archlinux> In-Reply-To: <5e653c4a.1c69fb81.e805f.b62a@mx.google.com> References: <5e653c4a.1c69fb81.e805f.b62a@mx.google.com> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 9 Mar 2020 00:11:06 +0530 Rohit Sarkar wrote: > Replace usage indio_dev's mlock with either local lock or > iio_device_claim_direct_mode. > > Signed-off-by: Rohit Sarkar Nearly there. A few minor issues around handling failure to claim direct mode (which will happen if the buffer is enabled). Jonathan > --- > Changelog v4 -> v5 > Use local lock too at places where driver state needs to be protected. > > Changelog v3 -> v4 > * Fix indentation > > Changelog v2 -> v3 > * use iio_device_claim_direct when switching modes > * replace mlock usage in max1363_write_event_config > > Changelog v1 -> v2 > * Fix indentation > > drivers/iio/adc/max1363.c | 30 +++++++++++++++++++++--------- > 1 file changed, 21 insertions(+), 9 deletions(-) > > diff --git a/drivers/iio/adc/max1363.c b/drivers/iio/adc/max1363.c > index 5c2cc61b666e..856f523e7018 100644 > --- a/drivers/iio/adc/max1363.c > +++ b/drivers/iio/adc/max1363.c > @@ -150,6 +150,7 @@ struct max1363_chip_info { > * @current_mode: the scan mode of this chip > * @requestedmask: a valid requested set of channels > * @reg: supply regulator > + * @lock lock to ensure state is consistent > * @monitor_on: whether monitor mode is enabled > * @monitor_speed: parameter corresponding to device monitor speed setting > * @mask_high: bitmask for enabled high thresholds > @@ -169,6 +170,7 @@ struct max1363_state { > const struct max1363_mode *current_mode; > u32 requestedmask; > struct regulator *reg; > + struct mutex lock; > > /* Using monitor modes and buffer at the same time is > currently not supported */ > @@ -364,7 +366,11 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev, > struct max1363_state *st = iio_priv(indio_dev); > struct i2c_client *client = st->client; > > - mutex_lock(&indio_dev->mlock); > + ret = iio_device_claim_direct_mode(indio_dev); If this fails, no locks are held, so return directly here. You don't want to call iio_device_release_direct_mode in that case. General rule of thumb in kernel is that a function returning an error should have no 'side effects' - it should be as if it never ran. > + mutex_lock(&st->lock); > + > + if (ret < 0) > + goto error_ret; > /* > * If monitor mode is enabled, the method for reading a single > * channel will have to be rather different and has not yet > @@ -372,7 +378,7 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev, > * > * Also, cannot read directly if buffered capture enabled. > */ > - if (st->monitor_on || iio_buffer_enabled(indio_dev)) { > + if (st->monitor_on) { > ret = -EBUSY; > goto error_ret; > } > @@ -404,8 +410,10 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev, > data = rxbuf[0]; > } > *val = data; > + > error_ret: > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&st->lock); > + iio_device_release_direct_mode(indio_dev); > return ret; > > } > @@ -705,9 +713,9 @@ static ssize_t max1363_monitor_store_freq(struct device *dev, > if (!found) > return -EINVAL; > > - mutex_lock(&indio_dev->mlock); > + mutex_lock(&st->lock); > st->monitor_speed = i; > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&st->lock); > > return 0; > } > @@ -810,12 +818,12 @@ static int max1363_read_event_config(struct iio_dev *indio_dev, > int val; > int number = chan->channel; > > - mutex_lock(&indio_dev->mlock); > + mutex_lock(&st->lock); > if (dir == IIO_EV_DIR_FALLING) > val = (1 << number) & st->mask_low; > else > val = (1 << number) & st->mask_high; > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&st->lock); > > return val; > } > @@ -962,7 +970,9 @@ static int max1363_write_event_config(struct iio_dev *indio_dev, > u16 unifiedmask; > int number = chan->channel; > > - mutex_lock(&indio_dev->mlock); > + iio_device_claim_direct_mode(indio_dev); You have to check the result claim_direct_mode. It will fail if we are in buffered mode. If that happens just return -EBUSY and don't do anything else. > + mutex_lock(&st->lock); > + > unifiedmask = st->mask_low | st->mask_high; > if (dir == IIO_EV_DIR_FALLING) { > > @@ -989,7 +999,8 @@ static int max1363_write_event_config(struct iio_dev *indio_dev, > > max1363_monitor_mode_update(st, !!(st->mask_high | st->mask_low)); > error_ret: > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&st->lock); > + iio_device_release_direct_mode(indio_dev); > > return ret; > } > @@ -1587,6 +1598,7 @@ static int max1363_probe(struct i2c_client *client, > > st = iio_priv(indio_dev); > > + mutex_init(&st->lock); > st->reg = devm_regulator_get(&client->dev, "vcc"); > if (IS_ERR(st->reg)) { > ret = PTR_ERR(st->reg);