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Sun, 18 Jan 2026 07:44:58 -0800 (PST) From: Kurt Borja Date: Sun, 18 Jan 2026 10:44:30 -0500 Subject: [PATCH v4 3/7] iio: core: Match iio_device_claim_*() semantics and implementation Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260118-lock-impr-v4-3-6c8d0aee8ed2@gmail.com> References: <20260118-lock-impr-v4-0-6c8d0aee8ed2@gmail.com> In-Reply-To: <20260118-lock-impr-v4-0-6c8d0aee8ed2@gmail.com> To: Andy Shevchenko , Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Benson Leung , Antoniu Miclaus , Gwendal Grignou , Shrikant Raskar , Per-Daniel Olsson Cc: David Lechner , =?utf-8?q?Nuno_S=C3=A1?= , Andy Shevchenko , Guenter Roeck , Jonathan Cameron , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, chrome-platform@lists.linux.dev, Kurt Borja X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=7969; i=kuurtb@gmail.com; h=from:subject:message-id; bh=8Qsn8l9ngnc+knSDLyebRMQVPK7UtYm5UK7xm5nz2xY=; b=owGbwMvMwCUmluBs8WX+lTTG02pJDJk5/z8Gvd9Vy8Y4fXrfdoNKtqN/qywsor5kWioZNHPp1 q26Z9PbUcrCIMbFICumyNKesOjbo6i8t34HQu/DzGFlAhnCwMUpABN5rsHwk3EbT2nxQblyXc1G O5nzAeHxb1gtcqomJp75XmRifvSjPcP/ktCF/2+sXvTmasWPmvCdEibFvN5hipar1SM7dVNNWaI 4AQ== X-Developer-Key: i=kuurtb@gmail.com; a=openpgp; fpr=54D3BE170AEF777983C3C63B57E3B6585920A69A Implement iio_device_claim_buffer_mode() fully inline with the use of __iio_dev_mode_lock(), which takes care of sparse annotations. To completely match iio_device_claim_direct() semantics, we need to also change iio_device_claim_buffer_mode() return semantics to usual true/false conditional lock semantics. Additionally, to avoid silently breaking out-of-tree drivers, rename iio_device_claim_buffer_mode() to iio_device_claim_try_buffer_mode(). Reviewed-by: David Lechner Reviewed-by: Nuno S=C3=A1 Signed-off-by: Kurt Borja --- drivers/iio/adc/ade9000.c | 2 +- .../common/cros_ec_sensors/cros_ec_sensors_core.c | 5 +-- drivers/iio/health/max30100.c | 8 +---- drivers/iio/health/max30102.c | 2 +- drivers/iio/industrialio-core.c | 42 +-----------------= ---- drivers/iio/light/opt4060.c | 2 +- include/linux/iio/iio.h | 35 ++++++++++++++++-- 7 files changed, 39 insertions(+), 57 deletions(-) diff --git a/drivers/iio/adc/ade9000.c b/drivers/iio/adc/ade9000.c index 2de8a718d62a..db085dc5e526 100644 --- a/drivers/iio/adc/ade9000.c +++ b/drivers/iio/adc/ade9000.c @@ -964,7 +964,7 @@ static irqreturn_t ade9000_dready_thread(int irq, void = *data) struct iio_dev *indio_dev =3D data; =20 /* Handle data ready interrupt from C4/EVENT/DREADY pin */ - if (!iio_device_claim_buffer_mode(indio_dev)) { + if (iio_device_try_claim_buffer_mode(indio_dev)) { ade9000_iio_push_buffer(indio_dev); iio_device_release_buffer_mode(indio_dev); } diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/dr= ivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c index 9ac80e4b7d75..ef53066b1735 100644 --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c @@ -188,11 +188,8 @@ int cros_ec_sensors_push_data(struct iio_dev *indio_de= v, /* * Ignore samples if the buffer is not set: it is needed if the ODR is * set but the buffer is not enabled yet. - * - * Note: iio_device_claim_buffer_mode() returns -EBUSY if the buffer - * is not enabled. */ - if (iio_device_claim_buffer_mode(indio_dev) < 0) + if (!iio_device_try_claim_buffer_mode(indio_dev)) return 0; =20 out =3D (s16 *)st->samples; diff --git a/drivers/iio/health/max30100.c b/drivers/iio/health/max30100.c index 3d441013893c..7dfdb5eb305e 100644 --- a/drivers/iio/health/max30100.c +++ b/drivers/iio/health/max30100.c @@ -417,13 +417,7 @@ static int max30100_read_raw(struct iio_dev *indio_dev, * Temperature reading can only be acquired while engine * is running */ - if (iio_device_claim_buffer_mode(indio_dev)) { - /* - * Replacing -EBUSY or other error code - * returned by iio_device_claim_buffer_mode() - * because user space may rely on the current - * one. - */ + if (!iio_device_try_claim_buffer_mode(indio_dev)) { ret =3D -EAGAIN; } else { ret =3D max30100_get_temp(data, val); diff --git a/drivers/iio/health/max30102.c b/drivers/iio/health/max30102.c index a48c0881a4c7..6918fcb5de2b 100644 --- a/drivers/iio/health/max30102.c +++ b/drivers/iio/health/max30102.c @@ -476,7 +476,7 @@ static int max30102_read_raw(struct iio_dev *indio_dev, * shutdown; leave shutdown briefly when buffer not running */ any_mode_retry: - if (iio_device_claim_buffer_mode(indio_dev)) { + if (!iio_device_try_claim_buffer_mode(indio_dev)) { /* * This one is a *bit* hacky. If we cannot claim buffer * mode, then try direct mode so that we make sure diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-cor= e.c index 83078285cd97..20cf316664b4 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -2183,7 +2183,7 @@ EXPORT_SYMBOL_GPL(__devm_iio_device_register); * * There are very few cases where a driver actually needs to lock the curr= ent * mode unconditionally. It's recommended to use iio_device_claim_direct()= or - * iio_device_claim_buffer_mode() pairs or related helpers instead. + * iio_device_try_claim_buffer_mode() pairs or related helpers instead. */ void __iio_dev_mode_lock(struct iio_dev *indio_dev) { @@ -2201,46 +2201,6 @@ void __iio_dev_mode_unlock(struct iio_dev *indio_dev) } EXPORT_SYMBOL_GPL(__iio_dev_mode_unlock); =20 -/** - * iio_device_claim_buffer_mode - Keep device in buffer mode - * @indio_dev: the iio_dev associated with the device - * - * If the device is in buffer mode it is guaranteed to stay - * that way until iio_device_release_buffer_mode() is called. - * - * Use with iio_device_release_buffer_mode(). - * - * Returns: 0 on success, -EBUSY on failure. - */ -int iio_device_claim_buffer_mode(struct iio_dev *indio_dev) -{ - struct iio_dev_opaque *iio_dev_opaque =3D to_iio_dev_opaque(indio_dev); - - mutex_lock(&iio_dev_opaque->mlock); - - if (iio_buffer_enabled(indio_dev)) - return 0; - - mutex_unlock(&iio_dev_opaque->mlock); - return -EBUSY; -} -EXPORT_SYMBOL_GPL(iio_device_claim_buffer_mode); - -/** - * iio_device_release_buffer_mode - releases claim on buffer mode - * @indio_dev: the iio_dev associated with the device - * - * Release the claim. Device is no longer guaranteed to stay - * in buffer mode. - * - * Use with iio_device_claim_buffer_mode(). - */ -void iio_device_release_buffer_mode(struct iio_dev *indio_dev) -{ - mutex_unlock(&to_iio_dev_opaque(indio_dev)->mlock); -} -EXPORT_SYMBOL_GPL(iio_device_release_buffer_mode); - /** * iio_device_get_current_mode() - helper function providing read-only acc= ess to * the opaque @currentmode variable diff --git a/drivers/iio/light/opt4060.c b/drivers/iio/light/opt4060.c index 981c704e7df5..8c4a1f562a83 100644 --- a/drivers/iio/light/opt4060.c +++ b/drivers/iio/light/opt4060.c @@ -304,7 +304,7 @@ static int opt4060_set_driver_state(struct iio_dev *ind= io_dev, struct opt4060_chip *chip =3D iio_priv(indio_dev); int ret =3D 0; any_mode_retry: - if (iio_device_claim_buffer_mode(indio_dev)) { + if (!iio_device_try_claim_buffer_mode(indio_dev)) { /* * This one is a *bit* hacky. If we cannot claim buffer mode, * then try direct mode so that we make sure things cannot diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index f6d494065efe..fa671e120e95 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -706,8 +706,39 @@ static inline bool iio_device_claim_direct(struct iio_= dev *indio_dev) */ #define iio_device_release_direct(indio_dev) __iio_dev_mode_unlock(indio_d= ev) =20 -int iio_device_claim_buffer_mode(struct iio_dev *indio_dev); -void iio_device_release_buffer_mode(struct iio_dev *indio_dev); +/** + * iio_device_try_claim_buffer_mode - Keep device in buffer mode + * @indio_dev: the iio_dev associated with the device + * + * If the device is in buffer mode it is guaranteed to stay + * that way until iio_device_release_buffer_mode() is called. + * + * Use with iio_device_release_buffer_mode(). + * + * Returns: true on success, false on failure. + */ +static inline bool iio_device_try_claim_buffer_mode(struct iio_dev *indio_= dev) +{ + __iio_dev_mode_lock(indio_dev); + + if (!iio_buffer_enabled(indio_dev)) { + __iio_dev_mode_unlock(indio_dev); + return false; + } + + return true; +} + +/** + * iio_device_release_buffer_mode - releases claim on buffer mode + * @indio_dev: the iio_dev associated with the device + * + * Release the claim. Device is no longer guaranteed to stay + * in buffer mode. + * + * Use with iio_device_try_claim_buffer_mode(). + */ +#define iio_device_release_buffer_mode(indio_dev) __iio_dev_mode_unlock(in= dio_dev) =20 extern const struct bus_type iio_bus_type; =20 --=20 2.52.0