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[79.18.120.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37d7fa87775sm1288894f8f.27.2024.10.15.04.06.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Oct 2024 04:06:47 -0700 (PDT) From: Matteo Martelli Date: Tue, 15 Oct 2024 13:06:34 +0200 Subject: [PATCH v3 1/5] iio: core: add read_avail_release_resource callback to fix race Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241015-iio-read-avail-release-v3-1-ac3e08f25cb3@gmail.com> References: <20241015-iio-read-avail-release-v3-0-ac3e08f25cb3@gmail.com> In-Reply-To: <20241015-iio-read-avail-release-v3-0-ac3e08f25cb3@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 Some iio drivers currently share an available info buffer that might be changed while iio core prints it to sysfs. To avoid the buffer corruption, add a release callback to let iio drivers allocate a copy of the available info buffer and later free it in the release callback. Such control is kept in the driver logic so that some driver that needs a big available info buffer might also perform some check to keep the copied buffer around in case no race has occurred. Signed-off-by: Matteo Martelli --- drivers/iio/industrialio-core.c | 14 +++++++++++--- include/linux/iio/iio.h | 4 ++++ 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 6a6568d4a2cb3a3f63381d5a6f25a2881b3ba2ed..4aea9de9f15a4d70f9d02fb3d47df49eef8c8423 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -859,12 +859,20 @@ static ssize_t iio_read_channel_info_avail(struct device *dev, return ret; switch (ret) { case IIO_AVAIL_LIST: - return iio_format_avail_list(buf, vals, type, length); + ret = iio_format_avail_list(buf, vals, type, length); + break; case IIO_AVAIL_RANGE: - return iio_format_avail_range(buf, vals, type); + ret = iio_format_avail_range(buf, vals, type); + break; default: - return -EINVAL; + ret = -EINVAL; } + + if (indio_dev->info->read_avail_release_resource) + indio_dev->info->read_avail_release_resource( + indio_dev, this_attr->c, vals, this_attr->address); + + return ret; } /** diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index 3a9b57187a958d6e65c699cf7814df5bac9a99e3..03bb765670a0c5f0129fc677c3a4a4cb38f4dad1 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -491,6 +491,10 @@ struct iio_info { int *length, long mask); + void (*read_avail_release_resource)(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + const int *vals, long mask); + int (*write_raw)(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int val, From patchwork Tue Oct 15 11:06:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matteo Martelli X-Patchwork-Id: 835693 Received: from mail-wm1-f50.google.com (mail-wm1-f50.google.com [209.85.128.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04B621E7664; Tue, 15 Oct 2024 11:06:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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[79.18.120.72]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4313f569943sm14423005e9.12.2024.10.15.04.06.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Oct 2024 04:06:50 -0700 (PDT) From: Matteo Martelli Date: Tue, 15 Oct 2024 13:06:36 +0200 Subject: [PATCH v3 3/5] iio: pac1921: use read_avail+release APIs instead of custom ext_info Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241015-iio-read-avail-release-v3-3-ac3e08f25cb3@gmail.com> References: <20241015-iio-read-avail-release-v3-0-ac3e08f25cb3@gmail.com> In-Reply-To: <20241015-iio-read-avail-release-v3-0-ac3e08f25cb3@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 a96fae546bc1e6d1bf3a0dbe67204c191d77a3ee..f6f8f9122a78d1b5e63d8184203eb3dae55eb560 100644 --- a/drivers/iio/adc/pac1921.c +++ b/drivers/iio/adc/pac1921.c @@ -444,11 +444,52 @@ static int pac1921_read_avail(struct iio_dev *indio_dev, *vals = pac1921_int_num_samples; *length = ARRAY_SIZE(pac1921_int_num_samples); return IIO_AVAIL_LIST; + case IIO_CHAN_INFO_SCALE: + switch (chan->channel) { + case PAC1921_CHAN_VBUS: + *vals = (const int *)pac1921_vbus_scales; + *length = ARRAY_SIZE(pac1921_vbus_scales) * 2; + *type = IIO_VAL_INT_PLUS_NANO; + return IIO_AVAIL_LIST; + + case PAC1921_CHAN_VSENSE: + *vals = (const int *)pac1921_vsense_scales; + *length = ARRAY_SIZE(pac1921_vsense_scales) * 2; + *type = IIO_VAL_INT_PLUS_NANO; + return IIO_AVAIL_LIST; + + case PAC1921_CHAN_CURRENT: { + struct pac1921_priv *priv = iio_priv(indio_dev); + + *length = ARRAY_SIZE(priv->current_scales) * 2; + *type = IIO_VAL_INT_PLUS_NANO; + + guard(mutex)(&priv->lock); + + *vals = 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; } } +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 == IIO_CHAN_INFO_SCALE && + chan->channel == 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 state. @@ -748,6 +789,7 @@ static int pac1921_read_event_value(struct iio_dev *indio_dev, static const struct iio_info pac1921_iio = { .read_raw = pac1921_read_raw, .read_avail = pac1921_read_avail, + .read_avail_release_resource = pac1921_read_avail_release_res, .write_raw = pac1921_write_raw, .write_raw_get_fmt = pac1921_write_raw_get_fmt, .read_label = pac1921_read_label, @@ -805,88 +847,7 @@ static ssize_t pac1921_write_shunt_resistor(struct iio_dev *indio_dev, return len; } -/* - * 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 = 0; - - for (unsigned int i = 0; i < size; i++) { - if (i != 0) { - len += sysfs_emit_at(buf, len, " "); - if (len >= PAGE_SIZE) - return -EFBIG; - } - len += sysfs_emit_at(buf, len, "%d.%09d", scales_tbl[i][0], - scales_tbl[i][1]); - if (len >= PAGE_SIZE) - return -EFBIG; - } - - len += 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 unlocked - * 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 = iio_priv(indio_dev); - const int (*scales_tbl)[2]; - size_t size; - - switch (chan->channel) { - case PAC1921_CHAN_VBUS: - scales_tbl = pac1921_vbus_scales; - size = ARRAY_SIZE(pac1921_vbus_scales); - return pac1921_format_scale_avail(scales_tbl, size, buf); - - case PAC1921_CHAN_VSENSE: - scales_tbl = pac1921_vsense_scales; - size = ARRAY_SIZE(pac1921_vsense_scales); - return pac1921_format_scale_avail(scales_tbl, size, buf); - - case PAC1921_CHAN_CURRENT: { - guard(mutex)(&priv->lock); - scales_tbl = priv->current_scales; - size = ARRAY_SIZE(priv->current_scales); - return pac1921_format_scale_avail(scales_tbl, size, buf); - } - default: - return -EINVAL; - } -} - -#define PAC1921_EXT_INFO_SCALE_AVAIL { \ - .name = "scale_available", \ - .read = pac1921_read_scale_avail, \ - .shared = IIO_SEPARATE, \ -} - -static const struct iio_chan_spec_ext_info pac1921_ext_info_voltage[] = { - PAC1921_EXT_INFO_SCALE_AVAIL, - {} -}; - static const struct iio_chan_spec_ext_info pac1921_ext_info_current[] = { - PAC1921_EXT_INFO_SCALE_AVAIL, { .name = "shunt_resistor", .read = pac1921_read_shunt_resistor, @@ -910,6 +871,7 @@ static const struct iio_chan_spec pac1921_channels[] = { .type = IIO_VOLTAGE, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | BIT(IIO_CHAN_INFO_SAMP_FREQ), @@ -927,12 +889,12 @@ static const struct iio_chan_spec pac1921_channels[] = { .indexed = 1, .event_spec = pac1921_overflow_event, .num_event_specs = ARRAY_SIZE(pac1921_overflow_event), - .ext_info = pac1921_ext_info_voltage, }, { .type = IIO_VOLTAGE, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | BIT(IIO_CHAN_INFO_SAMP_FREQ), @@ -950,12 +912,12 @@ static const struct iio_chan_spec pac1921_channels[] = { .indexed = 1, .event_spec = pac1921_overflow_event, .num_event_specs = ARRAY_SIZE(pac1921_overflow_event), - .ext_info = pac1921_ext_info_voltage, }, { .type = IIO_CURRENT, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | BIT(IIO_CHAN_INFO_SAMP_FREQ), From patchwork Tue Oct 15 11:06:38 2024 Content-Type: text/plain; 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[79.18.120.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37d7fa7a10dsm1289181f8f.2.2024.10.15.04.06.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Oct 2024 04:06:53 -0700 (PDT) From: Matteo Martelli Date: Tue, 15 Oct 2024 13:06:38 +0200 Subject: [PATCH v3 5/5] iio: as73211: copy/release available integration times to fix race Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241015-iio-read-avail-release-v3-5-ac3e08f25cb3@gmail.com> References: <20241015-iio-read-avail-release-v3-0-ac3e08f25cb3@gmail.com> In-Reply-To: <20241015-iio-read-avail-release-v3-0-ac3e08f25cb3@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 While available integration times are being printed to sysfs by iio core (iio_read_channel_info_avail), the sampling frequency might be changed. This could cause the buffer shared with iio core to be corrupted. To prevent it, make a copy of the integration times buffer and free it in the read_avail_release_resource callback. Signed-off-by: Matteo Martelli --- drivers/iio/light/as73211.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/drivers/iio/light/as73211.c b/drivers/iio/light/as73211.c index be0068081ebbbb37fdfb252b67a77b302ff725f6..c4c94873e6a1cc926cfb724d906b07222773c43f 100644 --- a/drivers/iio/light/as73211.c +++ b/drivers/iio/light/as73211.c @@ -108,7 +108,8 @@ struct as73211_spec_dev_data { * @creg1: Cached Configuration Register 1. * @creg2: Cached Configuration Register 2. * @creg3: Cached Configuration Register 3. - * @mutex: Keeps cached registers in sync with the device. + * @mutex: Keeps cached registers in sync with the device and protects + * int_time_avail concurrent access for updating and reading. * @completion: Completion to wait for interrupt. * @int_time_avail: Available integration times (depend on sampling frequency). * @spec_dev: device-specific configuration. @@ -493,17 +494,32 @@ static int as73211_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec co *type = IIO_VAL_INT; return IIO_AVAIL_LIST; - case IIO_CHAN_INFO_INT_TIME: + case IIO_CHAN_INFO_INT_TIME: { *length = ARRAY_SIZE(data->int_time_avail); - *vals = data->int_time_avail; *type = IIO_VAL_INT_PLUS_MICRO; - return IIO_AVAIL_LIST; + guard(mutex)(&data->mutex); + + *vals = kmemdup_array(data->int_time_avail, *length, + sizeof(int), GFP_KERNEL); + if (!*vals) + return -ENOMEM; + + return IIO_AVAIL_LIST; + } default: return -EINVAL; } } +static void as73211_read_avail_release_res(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + const int *vals, long mask) +{ + if (mask == IIO_CHAN_INFO_INT_TIME) + kfree(vals); +} + static int _as73211_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan __always_unused, int val, int val2, long mask) @@ -699,6 +715,7 @@ static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p) static const struct iio_info as73211_info = { .read_raw = as73211_read_raw, .read_avail = as73211_read_avail, + .read_avail_release_resource = as73211_read_avail_release_res, .write_raw = as73211_write_raw, };