linux-kernel - Re: [PATCH v3 2/2] staging: iio: ade7753: Replace mlock with driver private lock

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Message-ID: <87F68D7D-B342-486E-92A2-0C127E23E862@jic23.retrosnub.co.uk>
Date:   Thu, 23 Mar 2017 18:17:00 +0000
From:   Jonathan Cameron <jic23@...23.retrosnub.co.uk>
To:     SIMRAN SINGHAL <singhalsimran0@...il.com>,
        Jonathan Cameron <jic23@...nel.org>
CC:     Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Greg KH <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: [PATCH v3 2/2] staging: iio: ade7753: Replace mlock with driver private lock



On 23 March 2017 18:12:33 GMT+00:00, SIMRAN SINGHAL <singhalsimran0@...il.com> wrote:
>On Thu, Mar 23, 2017 at 1:55 AM, Jonathan Cameron <jic23@...nel.org>
>wrote:
>> On 21/03/17 18:03, 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.
>>>
>>> Signed-off-by: simran singhal <singhalsimran0@...il.com>
>> Mutex is not initialized...
>
>Mutex is already initialized in ade7753_probe().
Given you introduce a new mutex it seems unlikely that one is. You have to initialise each mutex.
>
>>> ---
>>>  drivers/staging/iio/meter/ade7753.c | 6 ++++--
>>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/staging/iio/meter/ade7753.c
>b/drivers/staging/iio/meter/ade7753.c
>>> index b71fbd3..9674e05 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;
>>>  }
>>>
>>

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