Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934993AbdCWTVk (ORCPT ); Thu, 23 Mar 2017 15:21:40 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:36319 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932110AbdCWTVf (ORCPT ); Thu, 23 Mar 2017 15:21:35 -0400 Date: Thu, 23 Mar 2017 12:21:17 -0700 From: Alison Schofield To: simran singhal Cc: lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org, knaack.h@gmx.de, pmeerw@pmeerw.net, gregkh@linuxfoundation.org, linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, outreachy-kernel@googlegroups.com Subject: Re: [Outreachy kernel] [PATCH v4] staging: iio: ade7753: Replace mlock with driver private lock Message-ID: <20170323192116.GA6614@d830.WORKGROUP> References: <20170323183520.GA9871@singhal-Inspiron-5558> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170323183520.GA9871@singhal-Inspiron-5558> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3006 Lines: 85 On Fri, Mar 24, 2017 at 12:05:20AM +0530, simran singhal wrote: > The IIO subsystem is redefining iio_dev->mlock to be used by > the IIO core only for protecting device operating mode changes. > ie. Changes between INDIO_DIRECT_MODE, INDIO_BUFFER_* modes. > > In this driver, mlock was being used to protect hardware state > changes. Replace it with a lock in the devices global data. Hi Simran, Please post all revision histories below the --- not just the most recent. Does this lock enforce the needed "atomicity" in the write_frequency function? I read Jonathans comment on a previous revision about "ensuring the spi bus frequency and sampling frequency of the device are changed in an atomic fashion" Is it possible for another spi bus transaction (read or write) to occur between the read and write in write_frequency? alisons > > Signed-off-by: simran singhal > --- > > v4: > -Add mutex_init > > drivers/staging/iio/meter/ade7753.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c > index b71fbd3..30aebaf 100644 > --- a/drivers/staging/iio/meter/ade7753.c > +++ b/drivers/staging/iio/meter/ade7753.c > @@ -80,11 +80,13 @@ > * @us: actual spi_device > * @tx: transmit buffer > * @rx: receive buffer > + * @lock: protect sensor state > * @buf_lock: mutex to protect tx and rx > **/ > struct ade7753_state { > struct spi_device *us; > struct mutex buf_lock; > + struct mutex lock; /* protect sensor state */ > u8 tx[ADE7753_MAX_TX] ____cacheline_aligned; > u8 rx[ADE7753_MAX_RX]; > }; > @@ -484,7 +486,7 @@ static ssize_t ade7753_write_frequency(struct device *dev, > if (!val) > return -EINVAL; > > - mutex_lock(&indio_dev->mlock); > + mutex_lock(&st->lock); > > t = 27900 / val; > if (t > 0) > @@ -505,7 +507,7 @@ static ssize_t ade7753_write_frequency(struct device *dev, > ret = ade7753_spi_write_reg_16(dev, ADE7753_MODE, reg); > > out: > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&st->lock); > > return ret ? ret : len; > } > @@ -581,6 +583,7 @@ static int ade7753_probe(struct spi_device *spi) > st = iio_priv(indio_dev); > st->us = spi; > mutex_init(&st->buf_lock); > + mutex_init(&st->lock); > > indio_dev->name = spi->dev.driver->name; > indio_dev->dev.parent = &spi->dev; > -- > 2.7.4 > > -- > You received this message because you are subscribed to the Google Groups "outreachy-kernel" group. > To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@googlegroups.com. > To post to this group, send email to outreachy-kernel@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20170323183520.GA9871%40singhal-Inspiron-5558. > For more options, visit https://groups.google.com/d/optout.