On Sat, Mar 25, 2017 at 05:56:54PM +0000, Jonathan Cameron wrote:
> On 23/03/17 17:36, Narcisa Ana Maria Vasile wrote:
> > This device operates in DIRECT_MODE and BUFFER_HARDWARE mode.
> > Replace usages of iio_dev->mlock with iio_device_{claim|release}_direct_mode()
> > helper functions to guarantee DIRECT mode and consequently protect
> > BUFFER mode too.
> >
> > Add and use a device private lock to protect against conflicting access of the
> > state data.
> > This helps with IIO subsystem 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.
> >
> > Remove lock from ad5933_work() because buffer mode should be enabled
> > when we reach this, and claiming DIRECT mode in all the other places
> > should protect it.
> Well presented. I was wondering about the logic behind that...
> >
> > Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@xxxxxxxxx>
> This is certainly a fiddly one so I'd like some more eyes on it.
>
> Lars - could you take a look? (he gets all the analog devices stuff ;)
Lars - Your thoughts?
Narcisa traced through the callbacks carefully since was the
only/first driver in IIO setting INDIO_BUFFER_HARDWARE.
thanks,
alisons
> > ---
> > drivers/staging/iio/impedance-analyzer/ad5933.c | 50 ++++++++++++++-----------
> > 1 file changed, 28 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
> > index 297665d..3d539ee 100644
> > --- a/drivers/staging/iio/impedance-analyzer/ad5933.c
> > +++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
> > @@ -98,6 +98,7 @@ struct ad5933_state {
> > struct i2c_client *client;
> > struct regulator *reg;
> > struct delayed_work work;
> > + struct mutex lock; /* Protect sensor state */
> > unsigned long mclk_hz;
> > unsigned char ctrl_hb;
> > unsigned char ctrl_lb;
> > @@ -306,9 +307,11 @@ static ssize_t ad5933_show_frequency(struct device *dev,
> > u8 d8[4];
> > } dat;
> >
> > - mutex_lock(&indio_dev->mlock);
> > + ret = iio_device_claim_direct_mode(indio_dev);
> > + if (ret)
> > + return ret;
> > ret = ad5933_i2c_read(st->client, this_attr->address, 3, &dat.d8[1]);
> > - mutex_unlock(&indio_dev->mlock);
> > + iio_device_release_direct_mode(indio_dev);
> > if (ret < 0)
> > return ret;
> >
> > @@ -338,9 +341,11 @@ static ssize_t ad5933_store_frequency(struct device *dev,
> > if (val > AD5933_MAX_OUTPUT_FREQ_Hz)
> > return -EINVAL;
> >
> > - mutex_lock(&indio_dev->mlock);
> > + ret = iio_device_claim_direct_mode(indio_dev);
> > + if (ret)
> > + return ret;
> > ret = ad5933_set_freq(st, this_attr->address, val);
> This is the one case that standas out where we aren't taking the new lock..
> It is setting a few internal state variables (st->freq_start and st->freq_inc)
> but this is safe because those aren't actually read anywhere..
> Presumably they were going to be cached, but the original author decided
> against at some point later...
> > - mutex_unlock(&indio_dev->mlock);
> > + iio_device_release_direct_mode(indio_dev);
> >
> > return ret ? ret : len;
> > }
> > @@ -364,7 +369,7 @@ static ssize_t ad5933_show(struct device *dev,
> > struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
> > int ret = 0, len = 0;
> >
> > - mutex_lock(&indio_dev->mlock);
> > + mutex_lock(&st->lock);
> > switch ((u32)this_attr->address) {
> > case AD5933_OUT_RANGE:
> > len = sprintf(buf, "%u\n",
> > @@ -393,7 +398,7 @@ static ssize_t ad5933_show(struct device *dev,
> > ret = -EINVAL;
> > }
> >
> > - mutex_unlock(&indio_dev->mlock);
> > + mutex_unlock(&st->lock);
> > return ret ? ret : len;
> > }
> >
> > @@ -415,7 +420,10 @@ static ssize_t ad5933_store(struct device *dev,
> > return ret;
> > }
> >
> > - mutex_lock(&indio_dev->mlock);
> > + ret = iio_device_claim_direct_mode(indio_dev);
> > + if (ret)
> > + return ret;
> > + mutex_lock(&st->lock);
> > switch ((u32)this_attr->address) {
> > case AD5933_OUT_RANGE:
> > ret = -EINVAL;
> > @@ -465,7 +473,8 @@ static ssize_t ad5933_store(struct device *dev,
> > ret = -EINVAL;
> > }
> >
> > - mutex_unlock(&indio_dev->mlock);
> > + mutex_unlock(&st->lock);
> > + iio_device_release_direct_mode(indio_dev);
> > return ret ? ret : len;
> > }
> >
> > @@ -532,11 +541,9 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
> >
> > switch (m) {
> > case IIO_CHAN_INFO_RAW:
> > - mutex_lock(&indio_dev->mlock);
> > - if (iio_buffer_enabled(indio_dev)) {
> > - ret = -EBUSY;
> > - goto out;
> > - }
> > + ret = iio_device_claim_direct_mode(indio_dev);
> > + if (ret)
> > + return ret;
> > ret = ad5933_cmd(st, AD5933_CTRL_MEASURE_TEMP);
> > if (ret < 0)
> > goto out;
> > @@ -549,7 +556,7 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
> > 2, (u8 *)&dat);
> > if (ret < 0)
> > goto out;
> > - mutex_unlock(&indio_dev->mlock);
> > + iio_device_release_direct_mode(indio_dev);
> > *val = sign_extend32(be16_to_cpu(dat), 13);
> >
> > return IIO_VAL_INT;
> > @@ -561,7 +568,7 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
> >
> > return -EINVAL;
> > out:
> > - mutex_unlock(&indio_dev->mlock);
> > + iio_device_release_direct_mode(indio_dev);
> > return ret;
> > }
> >
> > @@ -657,18 +664,17 @@ static void ad5933_work(struct work_struct *work)
> > unsigned char status;
> > int ret;
> >
> > - mutex_lock(&indio_dev->mlock);
> > if (st->state == AD5933_CTRL_INIT_START_FREQ) {
> > /* start sweep */
> > ad5933_cmd(st, AD5933_CTRL_START_SWEEP);
> > st->state = AD5933_CTRL_START_SWEEP;
> > schedule_delayed_work(&st->work, st->poll_time_jiffies);
> > - goto out;
> > + return;
> > }
> >
> > ret = ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
> > if (ret)
> > - goto out;
> > + return;
> >
> > if (status & AD5933_STAT_DATA_VALID) {
> > int scan_count = bitmap_weight(indio_dev->active_scan_mask,
> > @@ -678,7 +684,7 @@ static void ad5933_work(struct work_struct *work)
> > AD5933_REG_REAL_DATA : AD5933_REG_IMAG_DATA,
> > scan_count * 2, (u8 *)buf);
> > if (ret)
> > - goto out;
> > + return;
> >
> > if (scan_count == 2) {
> > val[0] = be16_to_cpu(buf[0]);
> > @@ -690,7 +696,7 @@ static void ad5933_work(struct work_struct *work)
> > } else {
> > /* no data available - try again later */
> > schedule_delayed_work(&st->work, st->poll_time_jiffies);
> > - goto out;
> > + return;
> > }
> >
> > if (status & AD5933_STAT_SWEEP_DONE) {
> > @@ -703,8 +709,6 @@ static void ad5933_work(struct work_struct *work)
> > ad5933_cmd(st, AD5933_CTRL_INC_FREQ);
> > schedule_delayed_work(&st->work, st->poll_time_jiffies);
> > }
> > -out:
> > - mutex_unlock(&indio_dev->mlock);
> > }
> >
> > static int ad5933_probe(struct i2c_client *client,
> > @@ -723,6 +727,8 @@ static int ad5933_probe(struct i2c_client *client,
> > i2c_set_clientdata(client, indio_dev);
> > st->client = client;
> >
> > + mutex_init(&st->lock);
> > +
> > if (!pdata)
> > pdata = &ad5933_default_pdata;
> >
> >
>
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