From: Alexandru Ardelean <alexandru.ardelean@analog.com> To: <linux-iio@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org> Cc: <linux-imx@nxp.com>, <festevam@gmail.com>, <jic23@kernel.org>, <shawnguo@kernel.org>, <s.hauer@pengutronix.de>, <kernel@pengutronix.de>, Sergiu Cuciurean <sergiu.cuciurean@analog.com>, Alexandru Ardelean <alexandru.ardelean@analog.com> Subject: [PATCH v2] iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock Date: Wed, 16 Sep 2020 12:29:28 +0300 [thread overview] Message-ID: <20200916092928.78026-1-alexandru.ardelean@analog.com> (raw) In-Reply-To: <20200826120609.203724-1-alexandru.ardelean@analog.com> 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
WARNING: multiple messages have this Message-ID (diff)
From: Alexandru Ardelean <alexandru.ardelean@analog.com> To: <linux-iio@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org> Cc: Sergiu Cuciurean <sergiu.cuciurean@analog.com>, festevam@gmail.com, s.hauer@pengutronix.de, linux-imx@nxp.com, kernel@pengutronix.de, Alexandru Ardelean <alexandru.ardelean@analog.com>, shawnguo@kernel.org, jic23@kernel.org Subject: [PATCH v2] iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock Date: Wed, 16 Sep 2020 12:29:28 +0300 [thread overview] Message-ID: <20200916092928.78026-1-alexandru.ardelean@analog.com> (raw) In-Reply-To: <20200826120609.203724-1-alexandru.ardelean@analog.com> 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
next prev parent reply other threads:[~2020-09-16 9:31 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-26 12:06 [PATCH] iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock Alexandru Ardelean 2020-08-29 15:29 ` Jonathan Cameron 2020-09-16 9:29 ` Alexandru Ardelean [this message] 2020-09-16 9:29 ` [PATCH v2] " Alexandru Ardelean 2020-09-17 18:27 ` Jonathan Cameron 2020-09-17 18:27 ` Jonathan Cameron
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