On Mon, 28 Sep 2020 16:13:33 +0300 Mircea Caprioru <mircea.caprioru@xxxxxxxxxx> wrote: > From: Sergiu Cuciurean <sergiu.cuciurean@xxxxxxxxxx> > > As part of the general cleanup of indio_dev->mlock, this change replaces > it with a local lock on the device's state structure. > > This is part of a bigger cleanup. > Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@xxxxxxxxxxxxxx/ > > Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@xxxxxxxxxx> > Signed-off-by: Mircea Caprioru <mircea.caprioru@xxxxxxxxxx> Another driver with buffered support which means we need to think harder about what is going on with these locks. > --- > drivers/iio/adc/rockchip_saradc.c | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-) > > diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c > index 1f3d7d639d37..80084c526cc6 100644 > --- a/drivers/iio/adc/rockchip_saradc.c > +++ b/drivers/iio/adc/rockchip_saradc.c > @@ -53,6 +53,15 @@ struct rockchip_saradc { > const struct rockchip_saradc_data *data; > u16 last_val; > const struct iio_chan_spec *last_chan; > + /* > + * Lock to protect the device state during a potential concurrent > + * read access from userspace. Reading a raw value requires a sequence > + * of register writes, then a wait for a completion callback, > + * and finally a register read, during which userspace could issue > + * another read request. This lock protects a read access from > + * ocurring before another one has finished. > + */ > + struct mutex lock; > }; > > static void rockchip_saradc_power_down(struct rockchip_saradc *info) > @@ -92,17 +101,17 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev, > > switch (mask) { > case IIO_CHAN_INFO_RAW: > - mutex_lock(&indio_dev->mlock); > + mutex_lock(&info->lock); Probably a case for iio_device_claim_direct_mode() as I doubt we want to enter buffered mode when halfway through this. > > ret = rockchip_saradc_conversion(info, chan); > if (ret) { > rockchip_saradc_power_down(info); > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&info->lock); > return ret; > } > > *val = info->last_val; > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&info->lock); > return IIO_VAL_INT; > case IIO_CHAN_INFO_SCALE: > ret = regulator_get_voltage(info->vref); > @@ -254,7 +263,7 @@ static irqreturn_t rockchip_saradc_trigger_handler(int irq, void *p) > int ret; > int i, j = 0; > > - mutex_lock(&i_dev->mlock); > + mutex_lock(&info->lock); Hmm. I wonder what this was meant to protect? I can't see why we need it if we are claiming direct mode correctly above. > > for_each_set_bit(i, i_dev->active_scan_mask, i_dev->masklength) { > const struct iio_chan_spec *chan = &i_dev->channels[i]; > @@ -271,7 +280,7 @@ static irqreturn_t rockchip_saradc_trigger_handler(int irq, void *p) > > iio_push_to_buffers_with_timestamp(i_dev, &data, iio_get_time_ns(i_dev)); > out: > - mutex_unlock(&i_dev->mlock); > + mutex_unlock(&info->lock); > > iio_trigger_notify_done(i_dev->trig); > > @@ -332,6 +341,8 @@ static int rockchip_saradc_probe(struct platform_device *pdev) > info->reset = NULL; > } > > + mutex_init(&info->lock); > + > init_completion(&info->completion); > > irq = platform_get_irq(pdev, 0);
