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[79.19.52.27]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42f79c67c5csm50718505e9.0.2024.10.03.10.34.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Oct 2024 10:34:41 -0700 (PDT) From: Matteo Martelli Date: Thu, 03 Oct 2024 19:34:07 +0200 Subject: [PATCH 2/7] iio: pac1921: use read_avail+release APIs instead of custom ext_info 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: <20241003-iio-read-avail-release-v1-2-c70cc7d9c2e0@gmail.com> References: <20241003-iio-read-avail-release-v1-0-c70cc7d9c2e0@gmail.com> In-Reply-To: <20241003-iio-read-avail-release-v1-0-c70cc7d9c2e0@gmail.com> To: Jonathan Cameron , Lars-Peter Clausen , Michael Hennerich , Alisa-Dariana Roman , Christian Eggers , Peter Rosin , Paul Cercueil , Sebastian Reichel Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-pm@vger.kernel.org, Matteo Martelli X-Mailer: b4 0.14.2 The pac1921 driver was exposing the available scale info via an ad-hoc ext_info attribute instead of using the read_avail API. This to avoid a possible race condition: while the available current scales were being printed to sysfs by iio core (iio_read_channel_info_avail), the shunt resistor might have been changed concurrently. Switch to the read_avail+release APIs now that the race condition has been addressed. Signed-off-by: Matteo Martelli --- drivers/iio/adc/pac1921.c | 128 ++++++++++++++++--------------------------= ---- 1 file changed, 45 insertions(+), 83 deletions(-) diff --git a/drivers/iio/adc/pac1921.c b/drivers/iio/adc/pac1921.c index 4c2a1c07bc399028f0334885fc9cd4552d5892b1..f491a4923380ef9b406a68f8cc4= 13df873869e3e 100644 --- a/drivers/iio/adc/pac1921.c +++ b/drivers/iio/adc/pac1921.c @@ -445,11 +445,52 @@ static int pac1921_read_avail(struct iio_dev *indio_d= ev, *vals =3D pac1921_int_num_samples; *length =3D ARRAY_SIZE(pac1921_int_num_samples); return IIO_AVAIL_LIST; + case IIO_CHAN_INFO_SCALE: + switch (chan->channel) { + case PAC1921_CHAN_VBUS: + *vals =3D (const int *)pac1921_vbus_scales; + *length =3D ARRAY_SIZE(pac1921_vbus_scales) * 2; + *type =3D IIO_VAL_INT_PLUS_NANO; + return IIO_AVAIL_LIST; + + case PAC1921_CHAN_VSENSE: + *vals =3D (const int *)pac1921_vsense_scales; + *length =3D ARRAY_SIZE(pac1921_vsense_scales) * 2; + *type =3D IIO_VAL_INT_PLUS_NANO; + return IIO_AVAIL_LIST; + + case PAC1921_CHAN_CURRENT: { + struct pac1921_priv *priv =3D iio_priv(indio_dev); + + *length =3D ARRAY_SIZE(priv->current_scales) * 2; + *type =3D IIO_VAL_INT_PLUS_NANO; + + guard(mutex)(&priv->lock); + + *vals =3D kmemdup_array((int *)priv->current_scales, + *length, sizeof(int), GFP_KERNEL); + if (!*vals) + return -ENOMEM; + + return IIO_AVAIL_LIST; + } + default: + return -EINVAL; + } default: return -EINVAL; } } =20 +static void pac1921_read_avail_release_res(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + const int *vals, long mask) +{ + if (mask =3D=3D IIO_CHAN_INFO_SCALE && + chan->channel =3D=3D PAC1921_CHAN_CURRENT) + kfree(vals); +} + /* * Perform configuration update sequence: set the device into read state, = then * write the config register and set the device back into integration stat= e. @@ -749,6 +790,7 @@ static int pac1921_read_event_value(struct iio_dev *ind= io_dev, static const struct iio_info pac1921_iio =3D { .read_raw =3D pac1921_read_raw, .read_avail =3D pac1921_read_avail, + .read_avail_release_resource =3D pac1921_read_avail_release_res, .write_raw =3D pac1921_write_raw, .write_raw_get_fmt =3D pac1921_write_raw_get_fmt, .read_label =3D pac1921_read_label, @@ -806,88 +848,7 @@ static ssize_t pac1921_write_shunt_resistor(struct iio= _dev *indio_dev, return len; } =20 -/* - * Emit on sysfs the list of available scales contained in scales_tbl - * - * TODO:: this function can be replaced with iio_format_avail_list() if the - * latter will ever be exported. - * - * Must be called with lock held if the scales_tbl can change runtime (e.g= . for - * the current scales table) - */ -static ssize_t pac1921_format_scale_avail(const int (*const scales_tbl)[2], - size_t size, char *buf) -{ - ssize_t len =3D 0; - - for (unsigned int i =3D 0; i < size; i++) { - if (i !=3D 0) { - len +=3D sysfs_emit_at(buf, len, " "); - if (len >=3D PAGE_SIZE) - return -EFBIG; - } - len +=3D sysfs_emit_at(buf, len, "%d.%09d", scales_tbl[i][0], - scales_tbl[i][1]); - if (len >=3D PAGE_SIZE) - return -EFBIG; - } - - len +=3D sysfs_emit_at(buf, len, "\n"); - return len; -} - -/* - * Read available scales for a specific channel - * - * NOTE: using extended info insted of iio.read_avail() because access to - * current scales must be locked as they depend on shunt resistor which may - * change runtime. Caller of iio.read_avail() would access the table unloc= ked - * instead. - */ -static ssize_t pac1921_read_scale_avail(struct iio_dev *indio_dev, - uintptr_t private, - const struct iio_chan_spec *chan, - char *buf) -{ - struct pac1921_priv *priv =3D iio_priv(indio_dev); - const int (*scales_tbl)[2]; - size_t size; - - switch (chan->channel) { - case PAC1921_CHAN_VBUS: - scales_tbl =3D pac1921_vbus_scales; - size =3D ARRAY_SIZE(pac1921_vbus_scales); - return pac1921_format_scale_avail(scales_tbl, size, buf); - - case PAC1921_CHAN_VSENSE: - scales_tbl =3D pac1921_vsense_scales; - size =3D ARRAY_SIZE(pac1921_vsense_scales); - return pac1921_format_scale_avail(scales_tbl, size, buf); - - case PAC1921_CHAN_CURRENT: { - guard(mutex)(&priv->lock); - scales_tbl =3D priv->current_scales; - size =3D ARRAY_SIZE(priv->current_scales); - return pac1921_format_scale_avail(scales_tbl, size, buf); - } - default: - return -EINVAL; - } -} - -#define PAC1921_EXT_INFO_SCALE_AVAIL { \ - .name =3D "scale_available", \ - .read =3D pac1921_read_scale_avail, \ - .shared =3D IIO_SEPARATE, \ -} - -static const struct iio_chan_spec_ext_info pac1921_ext_info_voltage[] =3D { - PAC1921_EXT_INFO_SCALE_AVAIL, - {} -}; - static const struct iio_chan_spec_ext_info pac1921_ext_info_current[] =3D { - PAC1921_EXT_INFO_SCALE_AVAIL, { .name =3D "shunt_resistor", .read =3D pac1921_read_shunt_resistor, @@ -911,6 +872,7 @@ static const struct iio_chan_spec pac1921_channels[] = =3D { .type =3D IIO_VOLTAGE, .info_mask_separate =3D BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .info_mask_separate_available =3D BIT(IIO_CHAN_INFO_SCALE), .info_mask_shared_by_all =3D BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | BIT(IIO_CHAN_INFO_SAMP_FREQ), @@ -928,12 +890,12 @@ static const struct iio_chan_spec pac1921_channels[] = =3D { .indexed =3D 1, .event_spec =3D pac1921_overflow_event, .num_event_specs =3D ARRAY_SIZE(pac1921_overflow_event), - .ext_info =3D pac1921_ext_info_voltage, }, { .type =3D IIO_VOLTAGE, .info_mask_separate =3D BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .info_mask_separate_available =3D BIT(IIO_CHAN_INFO_SCALE), .info_mask_shared_by_all =3D BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | BIT(IIO_CHAN_INFO_SAMP_FREQ), @@ -951,12 +913,12 @@ static const struct iio_chan_spec pac1921_channels[] = =3D { .indexed =3D 1, .event_spec =3D pac1921_overflow_event, .num_event_specs =3D ARRAY_SIZE(pac1921_overflow_event), - .ext_info =3D pac1921_ext_info_voltage, }, { .type =3D IIO_CURRENT, .info_mask_separate =3D BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .info_mask_separate_available =3D BIT(IIO_CHAN_INFO_SCALE), .info_mask_shared_by_all =3D BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | BIT(IIO_CHAN_INFO_SAMP_FREQ), --=20 2.46.2