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.
Fix some coding style issues related to white space also.
Signed-off-by: simran singhal <[email protected]>
---
drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
index dfd8b71..ca99d82 100644
--- a/drivers/staging/iio/meter/ade7753.c
+++ b/drivers/staging/iio/meter/ade7753.c
@@ -81,12 +81,14 @@
* @tx: transmit buffer
* @rx: receive buffer
* @buf_lock: mutex to protect tx and rx
+ * @lock: protect sensor state
**/
struct ade7753_state {
- struct spi_device *us;
- struct mutex buf_lock;
- u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
- u8 rx[ADE7753_MAX_RX];
+ 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];
};
static int ade7753_spi_write_reg_8(struct device *dev,
@@ -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;
}
--
2.7.4
On Sun, Mar 12, 2017 at 07:02:50PM +0530, 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.
>
> Fix some coding style issues related to white space also.
>
> Signed-off-by: simran singhal <[email protected]>
Hi Simran, This looks good to me. Let's see what the
reviewers say. I think the white space stuff is ok,
since it was right where you were editing.
alisons
> ---
> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
> index dfd8b71..ca99d82 100644
> --- a/drivers/staging/iio/meter/ade7753.c
> +++ b/drivers/staging/iio/meter/ade7753.c
> @@ -81,12 +81,14 @@
> * @tx: transmit buffer
> * @rx: receive buffer
> * @buf_lock: mutex to protect tx and rx
> + * @lock: protect sensor state
> **/
> struct ade7753_state {
> - struct spi_device *us;
> - struct mutex buf_lock;
> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
> - u8 rx[ADE7753_MAX_RX];
> + 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];
> };
>
> static int ade7753_spi_write_reg_8(struct device *dev,
> @@ -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;
> }
> --
> 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 [email protected].
> To post to this group, send email to [email protected].
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> For more options, visit https://groups.google.com/d/optout.
On Mon, Mar 13, 2017 at 12:03 AM, Alison Schofield <[email protected]> wrote:
> On Sun, Mar 12, 2017 at 07:02:50PM +0530, 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.
>>
>> Fix some coding style issues related to white space also.
>>
>> Signed-off-by: simran singhal <[email protected]>
>
> Hi Simran, This looks good to me. Let's see what the
> reviewers say. I think the white space stuff is ok,
> since it was right where you were editing.
> alisons
>
Alison, so sending this patch here on outreachy mailing list is fine.
Still confuse :P
>> ---
>> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
>> index dfd8b71..ca99d82 100644
>> --- a/drivers/staging/iio/meter/ade7753.c
>> +++ b/drivers/staging/iio/meter/ade7753.c
>> @@ -81,12 +81,14 @@
>> * @tx: transmit buffer
>> * @rx: receive buffer
>> * @buf_lock: mutex to protect tx and rx
>> + * @lock: protect sensor state
>> **/
>> struct ade7753_state {
>> - struct spi_device *us;
>> - struct mutex buf_lock;
>> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
>> - u8 rx[ADE7753_MAX_RX];
>> + 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];
>> };
>>
>> static int ade7753_spi_write_reg_8(struct device *dev,
>> @@ -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;
>> }
>> --
>> 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 [email protected].
>> To post to this group, send email to [email protected].
>> To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20170312133250.GA7772%40singhal-Inspiron-5558.
>> For more options, visit https://groups.google.com/d/optout.
On Mon, Mar 13, 2017 at 09:28:34AM +0530, SIMRAN SINGHAL wrote:
> On Mon, Mar 13, 2017 at 12:03 AM, Alison Schofield <[email protected]> wrote:
> > On Sun, Mar 12, 2017 at 07:02:50PM +0530, 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.
> >>
> >> Fix some coding style issues related to white space also.
> >>
> >> Signed-off-by: simran singhal <[email protected]>
> >
> > Hi Simran, This looks good to me. Let's see what the
> > reviewers say. I think the white space stuff is ok,
> > since it was right where you were editing.
> > alisons
> >
> Alison, so sending this patch here on outreachy mailing list is fine.
> Still confuse :P
You are OK. You sent it to everyone suggested in the Task Description.
This patch was sent before I posted the Task Description. I'm assuming
that since then you've found the posted Task:
https://kernelnewbies.org/IIO_tasks
Find Coding Task 2 --> "PATCHES need to be sent to all of:"
>
> >> ---
> >> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
> >> 1 file changed, 8 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
> >> index dfd8b71..ca99d82 100644
> >> --- a/drivers/staging/iio/meter/ade7753.c
> >> +++ b/drivers/staging/iio/meter/ade7753.c
> >> @@ -81,12 +81,14 @@
> >> * @tx: transmit buffer
> >> * @rx: receive buffer
> >> * @buf_lock: mutex to protect tx and rx
> >> + * @lock: protect sensor state
> >> **/
> >> struct ade7753_state {
> >> - struct spi_device *us;
> >> - struct mutex buf_lock;
> >> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
> >> - u8 rx[ADE7753_MAX_RX];
> >> + 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];
> >> };
> >>
> >> static int ade7753_spi_write_reg_8(struct device *dev,
> >> @@ -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;
> >> }
> >> --
> >> 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 [email protected].
> >> To post to this group, send email to [email protected].
> >> To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20170312133250.GA7772%40singhal-Inspiron-5558.
> >> For more options, visit https://groups.google.com/d/optout.
On 03/12/2017 02:32 PM, 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.
>
> Fix some coding style issues related to white space also.
>
> Signed-off-by: simran singhal <[email protected]>
> ---
> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
> index dfd8b71..ca99d82 100644
> --- a/drivers/staging/iio/meter/ade7753.c
> +++ b/drivers/staging/iio/meter/ade7753.c
> @@ -81,12 +81,14 @@
> * @tx: transmit buffer
> * @rx: receive buffer
> * @buf_lock: mutex to protect tx and rx
> + * @lock: protect sensor state
It might make sense to reuse the existing lock which currently protects the
read/write functions. You can do this by introducing a variant of
ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
implement the read-modify-write cycle in a protected section.
Looking through the driver there seem to be other places as well that do
read-modify-write that should be protected by a lock, but currently are not.
This might be a good task.
> **/
> struct ade7753_state {
> - struct spi_device *us;
> - struct mutex buf_lock;
> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
> - u8 rx[ADE7753_MAX_RX];
> + 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];
> };
>
> static int ade7753_spi_write_reg_8(struct device *dev,
> @@ -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;
> }
>
On Mon, Mar 13, 2017 at 5:30 PM, Lars-Peter Clausen <[email protected]> wrote:
> On 03/12/2017 02:32 PM, 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.
>>
>> Fix some coding style issues related to white space also.
>>
>> Signed-off-by: simran singhal <[email protected]>
>> ---
>> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
>> index dfd8b71..ca99d82 100644
>> --- a/drivers/staging/iio/meter/ade7753.c
>> +++ b/drivers/staging/iio/meter/ade7753.c
>> @@ -81,12 +81,14 @@
>> * @tx: transmit buffer
>> * @rx: receive buffer
>> * @buf_lock: mutex to protect tx and rx
>> + * @lock: protect sensor state
>
> It might make sense to reuse the existing lock which currently protects the
> read/write functions. You can do this by introducing a variant of
> ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
> implement the read-modify-write cycle in a protected section.
>
> Looking through the driver there seem to be other places as well that do
> read-modify-write that should be protected by a lock, but currently are not.
> This might be a good task.
>
Are you trying to say that their is no need of introducing "lock",
I can using "buf_lock" only.
Thanks!
>> **/
>> struct ade7753_state {
>> - struct spi_device *us;
>> - struct mutex buf_lock;
>> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
>> - u8 rx[ADE7753_MAX_RX];
>> + 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];
>> };
>>
>> static int ade7753_spi_write_reg_8(struct device *dev,
>> @@ -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;
>> }
>>
>
On 03/13/2017 01:33 PM, SIMRAN SINGHAL wrote:
> On Mon, Mar 13, 2017 at 5:30 PM, Lars-Peter Clausen <[email protected]> wrote:
>> On 03/12/2017 02:32 PM, 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.
>>>
>>> Fix some coding style issues related to white space also.
>>>
>>> Signed-off-by: simran singhal <[email protected]>
>>> ---
>>> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
>>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
>>> index dfd8b71..ca99d82 100644
>>> --- a/drivers/staging/iio/meter/ade7753.c
>>> +++ b/drivers/staging/iio/meter/ade7753.c
>>> @@ -81,12 +81,14 @@
>>> * @tx: transmit buffer
>>> * @rx: receive buffer
>>> * @buf_lock: mutex to protect tx and rx
>>> + * @lock: protect sensor state
>>
>> It might make sense to reuse the existing lock which currently protects the
>> read/write functions. You can do this by introducing a variant of
>> ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
>> implement the read-modify-write cycle in a protected section.
>>
>> Looking through the driver there seem to be other places as well that do
>> read-modify-write that should be protected by a lock, but currently are not.
>> This might be a good task.
>>
>
> Are you trying to say that their is no need of introducing "lock",
> I can using "buf_lock" only.
Yes, there should be no need for two locks. But you need to slightly
refactor the code to avoid taking the same lock nested.
>
> Thanks!
>
>>> **/
>>> struct ade7753_state {
>>> - struct spi_device *us;
>>> - struct mutex buf_lock;
>>> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
>>> - u8 rx[ADE7753_MAX_RX];
>>> + 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];
>>> };
>>>
>>> static int ade7753_spi_write_reg_8(struct device *dev,
>>> @@ -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;
>>> }
>>>
>>
On Mon, Mar 13, 2017 at 5:30 PM, Lars-Peter Clausen <[email protected]> wrote:
>
> On 03/12/2017 02:32 PM, 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.
> >
> > Fix some coding style issues related to white space also.
> >
> > Signed-off-by: simran singhal <[email protected]>
> > ---
> > drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
> > 1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
> > index dfd8b71..ca99d82 100644
> > --- a/drivers/staging/iio/meter/ade7753.c
> > +++ b/drivers/staging/iio/meter/ade7753.c
> > @@ -81,12 +81,14 @@
> > * @tx: transmit buffer
> > * @rx: receive buffer
> > * @buf_lock: mutex to protect tx and rx
> > + * @lock: protect sensor state
>
> It might make sense to reuse the existing lock which currently protects the
> read/write functions. You can do this by introducing a variant of
> ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
> implement the read-modify-write cycle in a protected section.
There are other read/write functions for example,
ade7753_spi_{read/write}_reg_8 that use the mutex as well. Should a
variant of these functions be introduced as well? Also, how does one
go about implementing RMW inside a protected section.
>
> Looking through the driver there seem to be other places as well that do
> read-modify-write that should be protected by a lock, but currently are not.
> This might be a good task.
Am I right in understanding that we want to introduce mutex lock for
writes in other drivers as well?
Thanks,
Gargi
>
> > **/
> > struct ade7753_state {
> > - struct spi_device *us;
> > - struct mutex buf_lock;
> > - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
> > - u8 rx[ADE7753_MAX_RX];
> > + 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];
> > };
> >
> > static int ade7753_spi_write_reg_8(struct device *dev,
> > @@ -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;
> > }
> >
>
> --
On 17/03/17 09:32, Gargi Sharma wrote:
> On Mon, Mar 13, 2017 at 5:30 PM, Lars-Peter Clausen <[email protected]> wrote:
>>
>> On 03/12/2017 02:32 PM, 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.
>>>
>>> Fix some coding style issues related to white space also.
>>>
>>> Signed-off-by: simran singhal <[email protected]>
>>> ---
>>> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
>>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
>>> index dfd8b71..ca99d82 100644
>>> --- a/drivers/staging/iio/meter/ade7753.c
>>> +++ b/drivers/staging/iio/meter/ade7753.c
>>> @@ -81,12 +81,14 @@
>>> * @tx: transmit buffer
>>> * @rx: receive buffer
>>> * @buf_lock: mutex to protect tx and rx
>>> + * @lock: protect sensor state
>>
>> It might make sense to reuse the existing lock which currently protects the
>> read/write functions. You can do this by introducing a variant of
>> ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
>> implement the read-modify-write cycle in a protected section.
>
> There are other read/write functions for example,
> ade7753_spi_{read/write}_reg_8 that use the mutex as well. Should a
> variant of these functions be introduced as well? Also, how does one
> go about implementing RMW inside a protected section.
Hmm. Simran has also been progressing with patches for this.
You raise a good question. There are other read/modify/write sequences in
the driver. They don't have the same issue with potentially deadlocking
against the buf lock as they are all using the spi subsystems provisions
for small write/read cycles where buffer protection is handled internally.
So let us address the cases in turn:
static int ade7753_reset(struct device *dev)
{
u16 val;
int ret;
ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
if (ret)
return ret;
val |= BIT(6); /* Software Chip Reset */
return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);
}
This is only called in the device initialization. At that point
we should be fine in assuming no parallel calls. Crucial point
is it is before the call to iio_device_register which exposes
the userspace interfaces.
static int ade7753_set_irq(struct device *dev, bool enable)
{
int ret;
u8 irqen;
ret = ade7753_spi_read_reg_8(dev, ADE7753_IRQEN, &irqen);
if (ret)
goto error_ret;
if (enable)
irqen |= BIT(3); /* Enables an interrupt when a data is
* present in the waveform register
*/
else
irqen &= ~BIT(3);
ret = ade7753_spi_write_reg_8(dev, ADE7753_IRQEN, irqen);
error_ret:
return ret;
}
This one is actually safe because it is the only function that
modifies that particular register.
/* Power down the device */
static int ade7753_stop_device(struct device *dev)
{
u16 val;
int ret;
ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
if (ret)
return ret;
val |= BIT(4); /* AD converters can be turned off */
return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);
}
Only called in remove (after userspace interfaces have been
removed by the iio_device_unregister call so also should not
be running concurrently with much else.
So I think all the other cases are safe. Perhaps it would have
been better to have had a lock around them, purely to make
the code more resilient against future changes though.
Probably a job to do as part of a larger scale pile of work
on that driver rather than as a one off patch.
Jonathan
>
>
>>
>> Looking through the driver there seem to be other places as well that do
>> read-modify-write that should be protected by a lock, but currently are not.
>> This might be a good task.
>
> Am I right in understanding that we want to introduce mutex lock for
> writes in other drivers as well?
>
> Thanks,
> Gargi
>>
>>> **/
>>> struct ade7753_state {
>>> - struct spi_device *us;
>>> - struct mutex buf_lock;
>>> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
>>> - u8 rx[ADE7753_MAX_RX];
>>> + 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];
>>> };
>>>
>>> static int ade7753_spi_write_reg_8(struct device *dev,
>>> @@ -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;
>>> }
>>>
>>
>> --
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
On Sun, Mar 19, 2017 at 4:01 PM, Jonathan Cameron <[email protected]> wrote:
> On 17/03/17 09:32, Gargi Sharma wrote:
>> On Mon, Mar 13, 2017 at 5:30 PM, Lars-Peter Clausen <[email protected]> wrote:
>>>
>>> On 03/12/2017 02:32 PM, 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.
>>>>
>>>> Fix some coding style issues related to white space also.
>>>>
>>>> Signed-off-by: simran singhal <[email protected]>
>>>> ---
>>>> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
>>>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
>>>> index dfd8b71..ca99d82 100644
>>>> --- a/drivers/staging/iio/meter/ade7753.c
>>>> +++ b/drivers/staging/iio/meter/ade7753.c
>>>> @@ -81,12 +81,14 @@
>>>> * @tx: transmit buffer
>>>> * @rx: receive buffer
>>>> * @buf_lock: mutex to protect tx and rx
>>>> + * @lock: protect sensor state
>>>
>>> It might make sense to reuse the existing lock which currently protects the
>>> read/write functions. You can do this by introducing a variant of
>>> ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
>>> implement the read-modify-write cycle in a protected section.
>>
>> There are other read/write functions for example,
>> ade7753_spi_{read/write}_reg_8 that use the mutex as well. Should a
>> variant of these functions be introduced as well? Also, how does one
>> go about implementing RMW inside a protected section.
> Hmm. Simran has also been progressing with patches for this.
>
I was trying to work through a patch for ade7754. So ran into the same
problem :)
> You raise a good question. There are other read/modify/write sequences in
> the driver. They don't have the same issue with potentially deadlocking
> against the buf lock as they are all using the spi subsystems provisions
> for small write/read cycles where buffer protection is handled internally.
>
> So let us address the cases in turn:
>
> static int ade7753_reset(struct device *dev)
> {
> u16 val;
> int ret;
>
> ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
> if (ret)
> return ret;
>
> val |= BIT(6); /* Software Chip Reset */
>
> return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);
> }
> This is only called in the device initialization. At that point
> we should be fine in assuming no parallel calls. Crucial point
> is it is before the call to iio_device_register which exposes
> the userspace interfaces.
>
> static int ade7753_set_irq(struct device *dev, bool enable)
> {
> int ret;
> u8 irqen;
>
> ret = ade7753_spi_read_reg_8(dev, ADE7753_IRQEN, &irqen);
> if (ret)
> goto error_ret;
>
> if (enable)
> irqen |= BIT(3); /* Enables an interrupt when a data is
> * present in the waveform register
> */
> else
> irqen &= ~BIT(3);
>
> ret = ade7753_spi_write_reg_8(dev, ADE7753_IRQEN, irqen);
>
> error_ret:
> return ret;
> }
>
> This one is actually safe because it is the only function that
> modifies that particular register.
>
> /* Power down the device */
> static int ade7753_stop_device(struct device *dev)
> {
> u16 val;
> int ret;
>
> ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
> if (ret)
> return ret;
>
> val |= BIT(4); /* AD converters can be turned off */
>
> return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);
> }
>
> Only called in remove (after userspace interfaces have been
> removed by the iio_device_unregister call so also should not
> be running concurrently with much else.
>
The only nested lock here is ade7754_spi_write_reg_16, so as long as
that is refactored, it'll be fine.
> So I think all the other cases are safe. Perhaps it would have
> been better to have had a lock around them, purely to make
> the code more resilient against future changes though.
> Probably a job to do as part of a larger scale pile of work
> on that driver rather than as a one off patch.
Another question that I have is why are we writing inside a read
function(ade7754_spi_read_reg_24)?
static int ade7754_spi_read_reg_24(struct device *dev,
u8 reg_address, u32 *val)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct ade7754_state *st = iio_priv(indio_dev);
int ret;
struct spi_transfer xfers[] = {
{
.tx_buf = st->tx,
.rx_buf = st->rx,
.bits_per_word = 8,
.len = 4,
},
};
mutex_lock(&st->buf_lock);
st->tx[0] = ADE7754_READ_REG(reg_address);
st->tx[1] = 0;
st->tx[2] = 0;
st->tx[3] = 0;
ret = spi_sync_transfer(st->us, xfers, ARRAY_SIZE(xfers));
if (ret) {
dev_err(&st->us->dev, "problem when reading 24 bit
register 0x%02X",
reg_address);
goto error_ret;
}
*val = (st->rx[1] << 16) | (st->rx[2] << 8) | st->rx[3];
error_ret:
mutex_unlock(&st->buf_lock);
return ret;
}
Thanks!
Gargi
>
> Jonathan
>
>
>
>
>
>
>
>>
>>
>>>
>>> Looking through the driver there seem to be other places as well that do
>>> read-modify-write that should be protected by a lock, but currently are not.
>>> This might be a good task.
>>
>> Am I right in understanding that we want to introduce mutex lock for
>> writes in other drivers as well?
>>
>> Thanks,
>> Gargi
>>>
>>>> **/
>>>> struct ade7753_state {
>>>> - struct spi_device *us;
>>>> - struct mutex buf_lock;
>>>> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
>>>> - u8 rx[ADE7753_MAX_RX];
>>>> + 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];
>>>> };
>>>>
>>>> static int ade7753_spi_write_reg_8(struct device *dev,
>>>> @@ -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;
>>>> }
>>>>
>>>
>>> --
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
>> the body of a message to [email protected]
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>
On 19/03/17 13:16, Gargi Sharma wrote:
> On Sun, Mar 19, 2017 at 4:01 PM, Jonathan Cameron <[email protected]> wrote:
>> On 17/03/17 09:32, Gargi Sharma wrote:
>>> On Mon, Mar 13, 2017 at 5:30 PM, Lars-Peter Clausen <[email protected]> wrote:
>>>>
>>>> On 03/12/2017 02:32 PM, 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.
>>>>>
>>>>> Fix some coding style issues related to white space also.
>>>>>
>>>>> Signed-off-by: simran singhal <[email protected]>
>>>>> ---
>>>>> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
>>>>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
>>>>> index dfd8b71..ca99d82 100644
>>>>> --- a/drivers/staging/iio/meter/ade7753.c
>>>>> +++ b/drivers/staging/iio/meter/ade7753.c
>>>>> @@ -81,12 +81,14 @@
>>>>> * @tx: transmit buffer
>>>>> * @rx: receive buffer
>>>>> * @buf_lock: mutex to protect tx and rx
>>>>> + * @lock: protect sensor state
>>>>
>>>> It might make sense to reuse the existing lock which currently protects the
>>>> read/write functions. You can do this by introducing a variant of
>>>> ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
>>>> implement the read-modify-write cycle in a protected section.
>>>
>>> There are other read/write functions for example,
>>> ade7753_spi_{read/write}_reg_8 that use the mutex as well. Should a
>>> variant of these functions be introduced as well? Also, how does one
>>> go about implementing RMW inside a protected section.
>> Hmm. Simran has also been progressing with patches for this.
>>
> I was trying to work through a patch for ade7754. So ran into the same
> problem :)
>
>> You raise a good question. There are other read/modify/write sequences in
>> the driver. They don't have the same issue with potentially deadlocking
>> against the buf lock as they are all using the spi subsystems provisions
>> for small write/read cycles where buffer protection is handled internally.
>>
>> So let us address the cases in turn:
>>
>> static int ade7753_reset(struct device *dev)
>> {
>> u16 val;
>> int ret;
>>
>> ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
>> if (ret)
>> return ret;
>>
>> val |= BIT(6); /* Software Chip Reset */
>>
>> return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);
>> }
>> This is only called in the device initialization. At that point
>> we should be fine in assuming no parallel calls. Crucial point
>> is it is before the call to iio_device_register which exposes
>> the userspace interfaces.
>>
>> static int ade7753_set_irq(struct device *dev, bool enable)
>> {
>> int ret;
>> u8 irqen;
>>
>> ret = ade7753_spi_read_reg_8(dev, ADE7753_IRQEN, &irqen);
>> if (ret)
>> goto error_ret;
>>
>> if (enable)
>> irqen |= BIT(3); /* Enables an interrupt when a data is
>> * present in the waveform register
>> */
>> else
>> irqen &= ~BIT(3);
>>
>> ret = ade7753_spi_write_reg_8(dev, ADE7753_IRQEN, irqen);
>>
>> error_ret:
>> return ret;
>> }
>>
>> This one is actually safe because it is the only function that
>> modifies that particular register.
>>
>> /* Power down the device */
>> static int ade7753_stop_device(struct device *dev)
>> {
>> u16 val;
>> int ret;
>>
>> ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
>> if (ret)
>> return ret;
>>
>> val |= BIT(4); /* AD converters can be turned off */
>>
>> return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);
>> }
>>
>> Only called in remove (after userspace interfaces have been
>> removed by the iio_device_unregister call so also should not
>> be running concurrently with much else.
>>
>
> The only nested lock here is ade7754_spi_write_reg_16, so as long as
> that is refactored, it'll be fine.
>
>> So I think all the other cases are safe. Perhaps it would have
>> been better to have had a lock around them, purely to make
>> the code more resilient against future changes though.
>> Probably a job to do as part of a larger scale pile of work
>> on that driver rather than as a one off patch.
>
> Another question that I have is why are we writing inside a read
> function(ade7754_spi_read_reg_24)?
>
It's a register read (sort of) hence the reg in the name.
It's telling it which register to read by first writing that.
> static int ade7754_spi_read_reg_24(struct device *dev,
> u8 reg_address, u32 *val)
> {
> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> struct ade7754_state *st = iio_priv(indio_dev);
> int ret;
> struct spi_transfer xfers[] = {
> {
> .tx_buf = st->tx,
> .rx_buf = st->rx,
> .bits_per_word = 8,
> .len = 4,
> },
> };
>
> mutex_lock(&st->buf_lock);
> st->tx[0] = ADE7754_READ_REG(reg_address);
> st->tx[1] = 0;
> st->tx[2] = 0;
> st->tx[3] = 0;
>
> ret = spi_sync_transfer(st->us, xfers, ARRAY_SIZE(xfers));
> if (ret) {
> dev_err(&st->us->dev, "problem when reading 24 bit
> register 0x%02X",
> reg_address);
> goto error_ret;
> }
> *val = (st->rx[1] << 16) | (st->rx[2] << 8) | st->rx[3];
>
> error_ret:
> mutex_unlock(&st->buf_lock);
> return ret;
> }
>
> Thanks!
> Gargi
>
>>
>> Jonathan
>>
>>
>>
>>
>>
>>
>>
>>>
>>>
>>>>
>>>> Looking through the driver there seem to be other places as well that do
>>>> read-modify-write that should be protected by a lock, but currently are not.
>>>> This might be a good task.
>>>
>>> Am I right in understanding that we want to introduce mutex lock for
>>> writes in other drivers as well?
>>>
>>> Thanks,
>>> Gargi
>>>>
>>>>> **/
>>>>> struct ade7753_state {
>>>>> - struct spi_device *us;
>>>>> - struct mutex buf_lock;
>>>>> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
>>>>> - u8 rx[ADE7753_MAX_RX];
>>>>> + 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];
>>>>> };
>>>>>
>>>>> static int ade7753_spi_write_reg_8(struct device *dev,
>>>>> @@ -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;
>>>>> }
>>>>>
>>>>
>>>> --
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
>>> the body of a message to [email protected]
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>
>>
On Mon, Mar 13, 2017 at 5:30 PM, Lars-Peter Clausen <[email protected]> wrote:
> On 03/12/2017 02:32 PM, 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.
>>
>> Fix some coding style issues related to white space also.
>>
>> Signed-off-by: simran singhal <[email protected]>
>> ---
>> drivers/staging/iio/meter/ade7753.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
>> index dfd8b71..ca99d82 100644
>> --- a/drivers/staging/iio/meter/ade7753.c
>> +++ b/drivers/staging/iio/meter/ade7753.c
>> @@ -81,12 +81,14 @@
>> * @tx: transmit buffer
>> * @rx: receive buffer
>> * @buf_lock: mutex to protect tx and rx
>> + * @lock: protect sensor state
>
> It might make sense to reuse the existing lock which currently protects the
> read/write functions. You can do this by introducing a variant of
> ade7753_spi_{read,write}_reg_16() that does not take a lock and use these to
> implement the read-modify-write cycle in a protected section.
>
The only instance I was able to find was drivers/iio/adc/vf610_adc.c
where read modify write cycles are present on the register
VF610_REG_ADC_CFG. I believe writel() & readl() is used for this
purpose.
In this case, we want to write to data to a device on the SPI bus. Can
we use writel() for this purpose?
> Looking through the driver there seem to be other places as well that do
> read-modify-write that should be protected by a lock, but currently are not.
> This might be a good task.
>
>> **/
>> struct ade7753_state {
>> - struct spi_device *us;
>> - struct mutex buf_lock;
>> - u8 tx[ADE7753_MAX_TX] ____cacheline_aligned;
>> - u8 rx[ADE7753_MAX_RX];
>> + 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];
>> };
>>
>> static int ade7753_spi_write_reg_8(struct device *dev,
>> @@ -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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