[PATCH v4] staging: Use buf_lock instead of mlock and Refactor code

[PATCH v4] staging: Use buf_lock instead of mlock and Refactor code

[simran singhal]

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.

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.

Signed-off-by: simran singhal <singhalsimran0@gmail.com>
---

 v4:
   -Refactored code 
   -change commit subject
   -change commit message

 drivers/staging/iio/gyro/adis16060_core.c | 37 ++++++++++++-------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
index c9d46e7..39ddd55 100644
--- a/drivers/staging/iio/gyro/adis16060_core.c
+++ b/drivers/staging/iio/gyro/adis16060_core.c
@@ -40,7 +40,7 @@ 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 val, u16 *val2)
 {
 	int ret;
 	struct adis16060_state *st = iio_priv(indio_dev);
@@ -48,17 +48,11 @@ static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val)
 	mutex_lock(&st->buf_lock);
 	st->buf[2] = val; /* 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) {
+		mutex_unlock(&st->buf_lock);
+		return ret;
+	}
 
 	ret = spi_read(st->us_r, st->buf, 3);
 
@@ -67,10 +61,10 @@ static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val)
 	 * starts to place data MSB first on the DOUT line at
 	 * the 6th falling edge of SCLK
 	 */
-	if (!ret)
-		*val = ((st->buf[0] & 0x3) << 12) |
-			(st->buf[1] << 4) |
-			((st->buf[2] >> 4) & 0xF);
+        if (!ret)
+		*val2 = ((st->buf[0] & 0x3) << 12) |
+			 (st->buf[1] << 4) |
+			 ((st->buf[2] >> 4) & 0xF);
 	mutex_unlock(&st->buf_lock);
 
 	return ret;
@@ -83,20 +77,17 @@ 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);
 		if (ret < 0)
 			goto out_unlock;
 
-		ret = adis16060_spi_read(indio_dev, &tval);
-		if (ret < 0)
-			goto out_unlock;
-
-		mutex_unlock(&indio_dev->mlock);
+		mutex_unlock(&st->buf_lock);
 		*val = tval;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_OFFSET:
@@ -112,7 +103,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
 	return -EINVAL;
 
 out_unlock:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&st->buf_lock);
 	return ret;
 }
 
-- 
2.7.4

Re: [PATCH v4] staging: Use buf_lock instead of mlock and Refactor code

[Jonathan Cameron]

On 18/03/17 18:44, 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 buf_lock in the devices global data.
> 
> 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.
> 
> Signed-off-by: simran singhal <singhalsimran0@gmail.com>
Hi Simran,

A couple of minor comments and opportunity to further improve
the, now simpler, code flow.

Thanks,

Jonathan
> ---
> 
>  v4:
>    -Refactored code 
>    -change commit subject
>    -change commit message
> 
>  drivers/staging/iio/gyro/adis16060_core.c | 37 ++++++++++++-------------------
>  1 file changed, 14 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
> index c9d46e7..39ddd55 100644
> --- a/drivers/staging/iio/gyro/adis16060_core.c
> +++ b/drivers/staging/iio/gyro/adis16060_core.c
> @@ -40,7 +40,7 @@ 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 val, u16 *val2)
val and val2 often have specific meanings in IIO.  I'd prefer these to be renamed to
val => conf (as it sets the configuration) and val2 => val.
>  {
>  	int ret;
>  	struct adis16060_state *st = iio_priv(indio_dev);
> @@ -48,17 +48,11 @@ static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val)
>  	mutex_lock(&st->buf_lock);
>  	st->buf[2] = val; /* 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) {
> +		mutex_unlock(&st->buf_lock);
> +		return ret;
> +	}
>  
>  	ret = spi_read(st->us_r, st->buf, 3);
>  
> @@ -67,10 +61,10 @@ static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val)
>  	 * starts to place data MSB first on the DOUT line at
>  	 * the 6th falling edge of SCLK
>  	 */
> -	if (!ret)
> -		*val = ((st->buf[0] & 0x3) << 12) |
> -			(st->buf[1] << 4) |
> -			((st->buf[2] >> 4) & 0xF);
> +        if (!ret)
Please run checkpatch.pl over your patches.  Looks like
you ended up with spaces instead of a tab in the line above.
> +		*val2 = ((st->buf[0] & 0x3) << 12) |
> +			 (st->buf[1] << 4) |
> +			 ((st->buf[2] >> 4) & 0xF);
>  	mutex_unlock(&st->buf_lock);
>  
>  	return ret;
> @@ -83,20 +77,17 @@ 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);
>  		if (ret < 0)
>  			goto out_unlock;
>  
> -		ret = adis16060_spi_read(indio_dev, &tval);
> -		if (ret < 0)
This ugly goto construction arguably made sense when there were two of them.  Now
you have only one just bring the mutex_unlock inline and return directly.
> -			goto out_unlock;
> -
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&st->buf_lock);
>  		*val = tval;
>  		return IIO_VAL_INT;
>  	case IIO_CHAN_INFO_OFFSET:
> @@ -112,7 +103,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
>  	return -EINVAL;
>  
>  out_unlock:
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->buf_lock);
>  	return ret;
>  }
>  
> 

Re: [PATCH v4] staging: Use buf_lock instead of mlock and Refactor code

[SIMRAN SINGHAL]

On Sun, Mar 19, 2017 at 3:45 PM, Jonathan Cameron <jic23@kernel.org> wrote:
> On 18/03/17 18:44, 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 buf_lock in the devices global data.
>>
>> 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.
>>
>> Signed-off-by: simran singhal <singhalsimran0@gmail.com>
> Hi Simran,
>
> A couple of minor comments and opportunity to further improve
> the, now simpler, code flow.
>
> Thanks,
>
> Jonathan
>> ---
>>
>>  v4:
>>    -Refactored code
>>    -change commit subject
>>    -change commit message
>>
>>  drivers/staging/iio/gyro/adis16060_core.c | 37 ++++++++++++-------------------
>>  1 file changed, 14 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
>> index c9d46e7..39ddd55 100644
>> --- a/drivers/staging/iio/gyro/adis16060_core.c
>> +++ b/drivers/staging/iio/gyro/adis16060_core.c
>> @@ -40,7 +40,7 @@ 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 val, u16 *val2)
> val and val2 often have specific meanings in IIO.  I'd prefer these to be renamed to
> val => conf (as it sets the configuration) and val2 => val.
>>  {
>>       int ret;
>>       struct adis16060_state *st = iio_priv(indio_dev);
>> @@ -48,17 +48,11 @@ static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val)
>>       mutex_lock(&st->buf_lock);
>>       st->buf[2] = val; /* 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) {
>> +             mutex_unlock(&st->buf_lock);
>> +             return ret;
>> +     }
>>
>>       ret = spi_read(st->us_r, st->buf, 3);
>>
>> @@ -67,10 +61,10 @@ static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val)
>>        * starts to place data MSB first on the DOUT line at
>>        * the 6th falling edge of SCLK
>>        */
>> -     if (!ret)
>> -             *val = ((st->buf[0] & 0x3) << 12) |
>> -                     (st->buf[1] << 4) |
>> -                     ((st->buf[2] >> 4) & 0xF);
>> +        if (!ret)
> Please run checkpatch.pl over your patches.  Looks like
> you ended up with spaces instead of a tab in the line above.

OOPS! My bad should have run checkpatch.pl
over patch.

Will correct all the checkpatch.pl issues and resend.

>> +             *val2 = ((st->buf[0] & 0x3) << 12) |
>> +                      (st->buf[1] << 4) |
>> +                      ((st->buf[2] >> 4) & 0xF);
>>       mutex_unlock(&st->buf_lock);
>>
>>       return ret;
>> @@ -83,20 +77,17 @@ 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);
>>               if (ret < 0)
>>                       goto out_unlock;
>>
>> -             ret = adis16060_spi_read(indio_dev, &tval);
>> -             if (ret < 0)
> This ugly goto construction arguably made sense when there were two of them.  Now
> you have only one just bring the mutex_unlock inline and return directly.

Will remove this and resend.

>> -                     goto out_unlock;
>> -
>> -             mutex_unlock(&indio_dev->mlock);
>> +             mutex_unlock(&st->buf_lock);
>>               *val = tval;
>>               return IIO_VAL_INT;
>>       case IIO_CHAN_INFO_OFFSET:
>> @@ -112,7 +103,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
>>       return -EINVAL;
>>
>>  out_unlock:
>> -     mutex_unlock(&indio_dev->mlock);
>> +     mutex_unlock(&st->buf_lock);
>>       return ret;
>>  }
>>
>>
>