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Message-ID: <20170321174706.GE2793@d830.WORKGROUP>
Date: Tue, 21 Mar 2017 10:47:06 -0700
From: Alison Schofield <amsfield22@...il.com>
To: SIMRAN SINGHAL <singhalsimran0@...il.com>
Cc: Lars-Peter Clausen <lars@...afoo.de>,
Michael Hennerich <Michael.Hennerich@...log.com>,
Jonathan Cameron <jic23@...nel.org>,
Hartmut Knaack <knaack.h@....de>,
Peter Meerwald-Stadler <pmeerw@...erw.net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
linux-kernel@...r.kernel.org,
outreachy-kernel <outreachy-kernel@...glegroups.com>
Subject: Re: [Outreachy kernel] [PATCH v6] staging: Use buf_lock instead of
mlock and Refactor code
On Tue, Mar 21, 2017 at 10:34:01PM +0530, SIMRAN SINGHAL wrote:
> On Tue, Mar 21, 2017 at 10:18 PM, Alison Schofield <amsfield22@...il.com> 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.
>
> Hi Alison,
> I have already sent v7 with changed subject.
Simran,
I see v7. Needs subsystem (iio) and to nitpick, driver name
is "adis16060" ;) Other comments still apply.
Please append all version histories below the --- for review.
v7:
v6:
.
.
v2:
thanks,
alisons
>
> >
> >> 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.
> >
> >>
> >> 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 <singhalsimran0@...il.com>
> >> ---
> >>
> >> 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
> >>
> >> --
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