* [PATCH v2] iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock [not found] <20200826120609.203724-1-alexandru.ardelean@analog.com> @ 2020-09-16 9:29 ` Alexandru Ardelean 2020-09-17 18:27 ` Jonathan Cameron 0 siblings, 1 reply; 2+ messages in thread From: Alexandru Ardelean @ 2020-09-16 9:29 UTC (permalink / raw) To: linux-iio, linux-arm-kernel, linux-kernel Cc: Sergiu Cuciurean, festevam, s.hauer, linux-imx, kernel, Alexandru Ardelean, shawnguo, jic23 From: Sergiu Cuciurean <sergiu.cuciurean@analog.com> As part of the general cleanup of indio_dev->mlock, this change replaces it with a local lock, to protect against any other accesses during the reading of sample. Reading a sample requires multiple consecutive regmap operations and a completion callback, so this requires that no other read occurs until it completes. This is part of a bigger cleanup. Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/ Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com> --- drivers/iio/adc/fsl-imx25-gcq.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c index 8cb51cf7a816..ab5139e911c3 100644 --- a/drivers/iio/adc/fsl-imx25-gcq.c +++ b/drivers/iio/adc/fsl-imx25-gcq.c @@ -40,6 +40,15 @@ struct mx25_gcq_priv { int irq; struct regulator *vref[4]; u32 channel_vref_mv[MX25_NUM_CFGS]; + /* + * 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; }; #define MX25_CQG_CHAN(chan, id) {\ @@ -137,9 +146,9 @@ static int mx25_gcq_read_raw(struct iio_dev *indio_dev, switch (mask) { case IIO_CHAN_INFO_RAW: - mutex_lock(&indio_dev->mlock); + mutex_lock(&priv->lock); ret = mx25_gcq_get_raw_value(&indio_dev->dev, chan, priv, val); - mutex_unlock(&indio_dev->mlock); + mutex_unlock(&priv->lock); return ret; case IIO_CHAN_INFO_SCALE: @@ -314,6 +323,8 @@ static int mx25_gcq_probe(struct platform_device *pdev) return PTR_ERR(priv->regs); } + mutex_init(&priv->lock); + init_completion(&priv->completed); ret = mx25_gcq_setup_cfgs(pdev, priv); -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock 2020-09-16 9:29 ` [PATCH v2] iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock Alexandru Ardelean @ 2020-09-17 18:27 ` Jonathan Cameron 0 siblings, 0 replies; 2+ messages in thread From: Jonathan Cameron @ 2020-09-17 18:27 UTC (permalink / raw) To: Alexandru Ardelean Cc: linux-iio, festevam, s.hauer, linux-kernel, Sergiu Cuciurean, linux-imx, kernel, shawnguo, linux-arm-kernel On Wed, 16 Sep 2020 12:29:28 +0300 Alexandru Ardelean <alexandru.ardelean@analog.com> wrote: > From: Sergiu Cuciurean <sergiu.cuciurean@analog.com> > > As part of the general cleanup of indio_dev->mlock, this change replaces > it with a local lock, to protect against any other accesses during the > reading of sample. Reading a sample requires multiple consecutive regmap > operations and a completion callback, so this requires that no other > read occurs until it completes. > > This is part of a bigger cleanup. > Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/ > > Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com> This seems simple enough so I've applied it to the togreg branch of iio.git Thanks, Jonathan > --- > drivers/iio/adc/fsl-imx25-gcq.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c > index 8cb51cf7a816..ab5139e911c3 100644 > --- a/drivers/iio/adc/fsl-imx25-gcq.c > +++ b/drivers/iio/adc/fsl-imx25-gcq.c > @@ -40,6 +40,15 @@ struct mx25_gcq_priv { > int irq; > struct regulator *vref[4]; > u32 channel_vref_mv[MX25_NUM_CFGS]; > + /* > + * 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; > }; > > #define MX25_CQG_CHAN(chan, id) {\ > @@ -137,9 +146,9 @@ static int mx25_gcq_read_raw(struct iio_dev *indio_dev, > > switch (mask) { > case IIO_CHAN_INFO_RAW: > - mutex_lock(&indio_dev->mlock); > + mutex_lock(&priv->lock); > ret = mx25_gcq_get_raw_value(&indio_dev->dev, chan, priv, val); > - mutex_unlock(&indio_dev->mlock); > + mutex_unlock(&priv->lock); > return ret; > > case IIO_CHAN_INFO_SCALE: > @@ -314,6 +323,8 @@ static int mx25_gcq_probe(struct platform_device *pdev) > return PTR_ERR(priv->regs); > } > > + mutex_init(&priv->lock); > + > init_completion(&priv->completed); > > ret = mx25_gcq_setup_cfgs(pdev, priv); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-09-16 9:29 ` [PATCH v2] iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock Alexandru Ardelean
2020-09-17 18:27 ` Jonathan Cameron
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