Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932758AbdCUSgL (ORCPT ); Tue, 21 Mar 2017 14:36:11 -0400 Received: from mail-vk0-f67.google.com ([209.85.213.67]:34056 "EHLO mail-vk0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757976AbdCUSew (ORCPT ); Tue, 21 Mar 2017 14:34:52 -0400 MIME-Version: 1.0 In-Reply-To: <20170321164812.GA2793@d830.WORKGROUP> References: <20170319200621.GA21295@singhal-Inspiron-5558> <20170321164812.GA2793@d830.WORKGROUP> From: SIMRAN SINGHAL Date: Wed, 22 Mar 2017 00:03:58 +0530 Message-ID: Subject: Re: [Outreachy kernel] [PATCH v6] staging: Use buf_lock instead of mlock and Refactor code To: Alison Schofield Cc: Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, outreachy-kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5473 Lines: 147 On Tue, Mar 21, 2017 at 10:18 PM, Alison Schofield wrote: > On Mon, Mar 20, 2017 at 01:36:21AM +0530, simran singhal wrote: > > Hi Simran, > > I going to ask for a v7 without looking at the code ;) > Subject line needs subsystem and driver. > Subject and log message can be improved. > >> 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 buf_lock in the devices global data. > ^^^^^^^^^^^ this was not done >> >> As buf_lock protects both the adis16060_spi_write() and >> adis16060_spi_read() functions and both are always called in >> pair. First write, then read. Thus, refactor the code to have >> one single function adis16060_spi_write_than_read() which is >> protected by the existing buf_lock. > This was done. So, you were able to obsolete the need for mlock > by creating the paired function. I am still using mlock but now locking it and performing both write and read and than unlocking. So, now have a single safe function. > >> >> Removed nested locks as the function adis16060_read_raw call >> a lock on &st->buf_lock and then calls the function >> adis16060_spi_write which again tries to get hold >> of the same lock. > ^^^^ this was not done. Yes, you avoided nested locks through > proper coding, but we don't want to give the impression in the > log message that there was a pre-existing nested lock issue. > > I did checkpatch & compile it...but looked no further yet. > > alisons >> >> Signed-off-by: simran singhal >> --- >> >> v6: >> -Change commit message >> -Remove nested lock >> >> drivers/staging/iio/gyro/adis16060_core.c | 40 ++++++++++--------------------- >> 1 file changed, 13 insertions(+), 27 deletions(-) >> >> diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c >> index c9d46e7..1c6de46 100644 >> --- a/drivers/staging/iio/gyro/adis16060_core.c >> +++ b/drivers/staging/iio/gyro/adis16060_core.c >> @@ -40,25 +40,17 @@ 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); >> >> @@ -69,8 +61,8 @@ static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val) >> */ >> if (!ret) >> *val = ((st->buf[0] & 0x3) << 12) | >> - (st->buf[1] << 4) | >> - ((st->buf[2] >> 4) & 0xF); >> + (st->buf[1] << 4) | >> + ((st->buf[2] >> 4) & 0xF); >> mutex_unlock(&st->buf_lock); >> >> return ret; >> @@ -83,20 +75,18 @@ static int adis16060_read_raw(struct iio_dev *indio_dev, >> { >> u16 tval = 0; >> int ret; >> + struct adis16060_state *st = iio_priv(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); >> + mutex_lock(&st->buf_lock); >> + ret = adis16060_spi_write_than_read(indio_dev, >> + chan->address, &tval); >> + mutex_unlock(&st->buf_lock); >> 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 +100,6 @@ 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 = { >> -- >> 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/20170319200621.GA21295%40singhal-Inspiron-5558. >> For more options, visit https://groups.google.com/d/optout.