Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935076AbdCVTWc (ORCPT ); Wed, 22 Mar 2017 15:22:32 -0400 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:48102 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935003AbdCVTWX (ORCPT ); Wed, 22 Mar 2017 15:22:23 -0400 Subject: Re: [PATCH v8] staging: adis16060: Remove iio_dev mlock and refactor code To: simran singhal , lars@metafoo.de References: <20170322162042.GA7955@singhal-Inspiron-5558> Cc: Michael.Hennerich@analog.com, Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, outreachy-kernel@googlegroups.com From: Jonathan Cameron Message-ID: Date: Wed, 22 Mar 2017 19:22:20 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170322162042.GA7955@singhal-Inspiron-5558> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3920 Lines: 125 On 22/03/17 16:20, 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. > > In the driver, buf_lock protects both the adis16060_spi_write() and > adis16060_spi_read() functions and both are always called in > pair. First write, then read. Refactor the code to have > one single function adis16060_spi_write_than_read() and remove > the use of mlock as adis16060_read_raw() does not require an > iio_dev->mlock for reads. I'll slightly modify this description. The key thing is that after the above change to have a unified read then write there is no longer any need for mlock to protect these read, update, write cycles. > > Signed-off-by: simran singhal Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders to play with it. I slightly modified the title as well. It's useful to be a little more specific than staging, so I added iio: after that. Thanks, Jonathan > --- > > v8: > -change subject > -change commit message > v7: > -Change subject > -Remove lock from read_raw instead from > function adis16060_spi_write_than_read(). > v6: > -Change commit message > -Remove nested lock > v5: > -Rename val in adis16060_spi_write_than_read() to conf. > -Rename val2 in adis16060_spi_write_than_read() to val. > -Corrected Checkpatch issues. > -Removed goto from adis16060_read_raw(). > v4: > -Refactored code > -change commit subject > -change commit message > v3: > -Removed new lock to reuse the existing lock > v2: > -Fixed compilation error > > drivers/staging/iio/gyro/adis16060_core.c | 33 ++++++++----------------------- > 1 file changed, 8 insertions(+), 25 deletions(-) > > diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c > index c9d46e7..e96fce5 100644 > --- a/drivers/staging/iio/gyro/adis16060_core.c > +++ b/drivers/staging/iio/gyro/adis16060_core.c > @@ -40,25 +40,18 @@ struct adis16060_state { > > static struct iio_dev *adis16060_iio_dev; > > -static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val) > +static int adis16060_spi_write_than_read(struct iio_dev *indio_dev, > + u8 conf, u16 *val) > { > int ret; > struct adis16060_state *st = iio_priv(indio_dev); > > mutex_lock(&st->buf_lock); > - st->buf[2] = val; /* The last 8 bits clocked in are latched */ > + st->buf[2] = conf; /* The last 8 bits clocked in are latched */ > ret = spi_write(st->us_w, st->buf, 3); > - mutex_unlock(&st->buf_lock); > - > - return ret; > -} > - > -static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val) > -{ > - int ret; > - struct adis16060_state *st = iio_priv(indio_dev); > > - mutex_lock(&st->buf_lock); > + if (ret < 0) > + return ret; > > ret = spi_read(st->us_r, st->buf, 3); > > @@ -86,17 +79,11 @@ static int adis16060_read_raw(struct iio_dev *indio_dev, > > switch (mask) { > case IIO_CHAN_INFO_RAW: > - /* Take the iio_dev status lock */ > - mutex_lock(&indio_dev->mlock); > - ret = adis16060_spi_write(indio_dev, chan->address); > + ret = adis16060_spi_write_than_read(indio_dev, > + chan->address, &tval); > if (ret < 0) > - goto out_unlock; > + return ret; > > - ret = adis16060_spi_read(indio_dev, &tval); > - if (ret < 0) > - goto out_unlock; > - > - mutex_unlock(&indio_dev->mlock); > *val = tval; > return IIO_VAL_INT; > case IIO_CHAN_INFO_OFFSET: > @@ -110,10 +97,6 @@ static int adis16060_read_raw(struct iio_dev *indio_dev, > } > > return -EINVAL; > - > -out_unlock: > - mutex_unlock(&indio_dev->mlock); > - return ret; > } > > static const struct iio_info adis16060_info = { >