On Sat, 9 Mar 2019 18:37:01 +0000 Jonathan Cameron <[email protected]> wrote:
> On Sat, 9 Mar 2019 17:29:36 +0100 > Tomasz Duszynski <[email protected]> wrote: > > > On Fri, Mar 08, 2019 at 02:03:27PM -0800, [email protected] wrote: > > > From: Justin Chen <[email protected]> > > > > > > Indio->mlock is used for protecting the different iio device modes. > > > It is currently not being used in this way. Replace the lock with > > > an internal lock specifically used for protecting the SPI transfer > > > buffer. > > > > > > Signed-off-by: Justin Chen <[email protected]> > > > --- > > > drivers/iio/adc/ti-ads7950.c | 19 +++++++++++++++---- > > > 1 file changed, 15 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c > > > index 0ad6359..1e47bef 100644 > > > --- a/drivers/iio/adc/ti-ads7950.c > > > +++ b/drivers/iio/adc/ti-ads7950.c > > > @@ -56,6 +56,9 @@ struct ti_ads7950_state { > > > struct spi_message ring_msg; > > > struct spi_message scan_single_msg; > > > > > > + /* Lock to protect the spi xfer buffers */ > > > + struct mutex slock; > > > + > > > struct regulator *reg; > > > unsigned int vref_mv; > > > > > > @@ -268,6 +271,7 @@ static irqreturn_t ti_ads7950_trigger_handler(int > > > irq, void *p) > > > struct ti_ads7950_state *st = iio_priv(indio_dev); > > > int ret; > > > > > > + mutex_lock(&st->slock); > > > ret = spi_sync(st->spi, &st->ring_msg); > > > if (ret < 0) > > > goto out; > > > @@ -276,6 +280,7 @@ static irqreturn_t ti_ads7950_trigger_handler(int > > > irq, void *p) > > > iio_get_time_ns(indio_dev)); > > > > > > out: > > > + mutex_unlock(&st->slock); > > > iio_trigger_notify_done(indio_dev->trig); > > > > > > return IRQ_HANDLED; > > > @@ -286,7 +291,7 @@ static int ti_ads7950_scan_direct(struct iio_dev > > > *indio_dev, unsigned int ch) > > > struct ti_ads7950_state *st = iio_priv(indio_dev); > > > int ret, cmd; > > > > > > - mutex_lock(&indio_dev->mlock); > > > + mutex_lock(&st->slock); > > > > > > cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(ch) | st->settings; > > > st->single_tx = cmd; > > > @@ -298,7 +303,7 @@ static int ti_ads7950_scan_direct(struct iio_dev > > > *indio_dev, unsigned int ch) > > > ret = st->single_rx; > > > > > > out: > > > - mutex_unlock(&indio_dev->mlock); > > > + mutex_unlock(&st->slock); > > > > > > return ret; > > > } > > > @@ -432,16 +437,19 @@ static int ti_ads7950_probe(struct spi_device *spi) > > > if (ACPI_COMPANION(&spi->dev)) > > > st->vref_mv = TI_ADS7950_VA_MV_ACPI_DEFAULT; > > > > > > + mutex_init(&st->slock); > > > + > > > st->reg = devm_regulator_get(&spi->dev, "vref"); > > > if (IS_ERR(st->reg)) { > > > dev_err(&spi->dev, "Failed get get regulator \"vref\"\n"); > > > - return PTR_ERR(st->reg); > > > + ret = PTR_ERR(st->reg); > > > + goto error_destroy_mutex; > > > } > > > > > > ret = regulator_enable(st->reg); > > > if (ret) { > > > dev_err(&spi->dev, "Failed to enable regulator \"vref\"\n"); > > > - return ret; > > > + goto error_destroy_mutex; > > > } > > > > > > ret = iio_triggered_buffer_setup(indio_dev, NULL, > > > @@ -463,6 +471,8 @@ static int ti_ads7950_probe(struct spi_device *spi) > > > iio_triggered_buffer_cleanup(indio_dev); > > > error_disable_reg: > > > regulator_disable(st->reg); > > > +error_destroy_mutex: > > > + mutex_destroy(&st->slock); > > > > If your intention was to do resources cleanup then this is not > > what this api was designed for. This is actually for debugging unwanted > > subsequent mutex usage. > > Yes. In a case like this where it is the last thing in a remove > it adds little value as there should be nothing left to take the mutex > anyway. This is the reason (I guess) there has never been a > devm_mutex_init function to tidy this up automatically... > Having said that, I just realised I applied this anyway last week. I'm not fussed enough about this to revert the change, so right now the mutex_destroys are there. Jonathan > > > > > > > > return ret; > > > } > > > @@ -475,6 +485,7 @@ static int ti_ads7950_remove(struct spi_device *spi) > > > iio_device_unregister(indio_dev); > > > iio_triggered_buffer_cleanup(indio_dev); > > > regulator_disable(st->reg); > > > + mutex_destroy(&st->slock); > > > > > > return 0; > > > } > > > -- > > > 2.7.4 > > > >
