iio: adc: ad7173: fix using shared static info struct

Fix a possible race condition during driver probe in the ad7173 driver
due to using a shared static info struct. If more that one instance of
the driver is probed at the same time, some of the info could be
overwritten by the other instance, leading to incorrect operation.

To fix this, make the static info struct const so that it is read-only
and make a copy of the info struct for each instance of the driver that
can be modified.

Reported-by: Uwe Kleine-König <[email protected]>
Fixes: 76a1e6a ("iio: adc: ad7173: add AD7173 driver")
Signed-off-by: David Lechner <[email protected]>
Tested-by: Guillaume Ranquet <[email protected]>
Link: https://patch.msgid.link/20241127-iio-adc-ad7313-fix-non-const-info-struct-v2-1-b6d7022b7466@baylibre.com
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

Author: dlech

drivers/iio/adc/ad7173.c

@@ -200,6 +200,7 @@ struct ad7173_channel {
 
 struct ad7173_state {
 	struct ad_sigma_delta sd;
+	struct ad_sigma_delta_info sigma_delta_info;
 	const struct ad7173_device_info *info;
 	struct ad7173_channel *channels;
 	struct regulator_bulk_data regulators[3];
@@ -753,7 +754,7 @@ static int ad7173_disable_one(struct ad_sigma_delta *sd, unsigned int chan)
 	return ad_sd_write_reg(sd, AD7173_REG_CH(chan), 2, 0);
 }
 
-static struct ad_sigma_delta_info ad7173_sigma_delta_info = {
+static const struct ad_sigma_delta_info ad7173_sigma_delta_info = {
 	.set_channel = ad7173_set_channel,
 	.append_status = ad7173_append_status,
 	.disable_all = ad7173_disable_all,
@@ -1403,7 +1404,7 @@ static int ad7173_fw_parse_device_config(struct iio_dev *indio_dev)
 	if (ret < 0)
 		return dev_err_probe(dev, ret, "Interrupt 'rdy' is required\n");
 
-	ad7173_sigma_delta_info.irq_line = ret;
+	st->sigma_delta_info.irq_line = ret;
 
 	return ad7173_fw_parse_channel_config(indio_dev);
 }
@@ -1436,8 +1437,9 @@ static int ad7173_probe(struct spi_device *spi)
 	spi->mode = SPI_MODE_3;
 	spi_setup(spi);
 
-	ad7173_sigma_delta_info.num_slots = st->info->num_configs;
-	ret = ad_sd_init(&st->sd, indio_dev, spi, &ad7173_sigma_delta_info);
+	st->sigma_delta_info = ad7173_sigma_delta_info;
+	st->sigma_delta_info.num_slots = st->info->num_configs;
+	ret = ad_sd_init(&st->sd, indio_dev, spi, &st->sigma_delta_info);
 	if (ret)
 		return ret;