The channel index is off by one unit if AS73211_SCAN_MASK_ALL is not set (optimized path for color channel readings), and it must be shifted instead of leaving an empty channel for the temperature when it is off.
Once the channel index is fixed, the uninitialized channel must be set to zero to avoid pushing uninitialized data.
Add available_scan_masks for all channels and only-color channels to let the IIO core demux and repack the enabled channels.
Cc: stable@vger.kernel.org Fixes: 403e5586b52e ("iio: light: as73211: New driver") Tested-by: Christian Eggers ceggers@arri.de Signed-off-by: Javier Carrasco javier.carrasco.cruz@gmail.com --- This issue was found after attempting to make the same mistake for a driver I maintain, which was fortunately spotted by Jonathan [1].
Keeping old sensor values if the channel configuration changes is known and not considered an issue, which is also mentioned in [1], so it has not been addressed by this series. That keeps most of the drivers out of the way because they store the scan element in iio private data, which is kzalloc() allocated.
This series only addresses cases where uninitialized i.e. unknown data is pushed to the userspace, either due to holes in structs or uninitialized struct members/array elements.
While analyzing involved functions, I found and fixed some triviality (wrong function name) in the documentation of iio_dev_opaque.
Link: https://lore.kernel.org/linux-iio/20241123151634.303aa860@jic23-huawei/ [1] --- Changes in v3: - as73211.c: add available_scan_masks for all channels and only-color channels to let the IIO core demux and repack the enabled channels. - Link to v2: https://lore.kernel.org/r/20241204-iio_memset_scan_holes-v2-0-3f941592a76d@g...
Changes in v2: - as73211.c: shift channels if no temperature is available and initialize chan[3] to zero. - Link to v1: https://lore.kernel.org/r/20241125-iio_memset_scan_holes-v1-0-0cb6e98d895c@g... --- drivers/iio/light/as73211.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/drivers/iio/light/as73211.c b/drivers/iio/light/as73211.c index be0068081ebb..4be2e349a068 100644 --- a/drivers/iio/light/as73211.c +++ b/drivers/iio/light/as73211.c @@ -177,6 +177,12 @@ struct as73211_data { BIT(AS73211_SCAN_INDEX_TEMP) | \ AS73211_SCAN_MASK_COLOR)
+static const unsigned long as73211_scan_masks[] = { + AS73211_SCAN_MASK_ALL, + AS73211_SCAN_MASK_COLOR, + 0, +}; + static const struct iio_chan_spec as73211_channels[] = { { .type = IIO_TEMP, @@ -672,9 +678,12 @@ static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p)
/* AS73211 starts reading at address 2 */ ret = i2c_master_recv(data->client, - (char *)&scan.chan[1], 3 * sizeof(scan.chan[1])); + (char *)&scan.chan[0], 3 * sizeof(scan.chan[0])); if (ret < 0) goto done; + + /* Avoid pushing uninitialized data */ + scan.chan[3] = 0; }
if (data_result) { @@ -682,9 +691,15 @@ static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p) * Saturate all channels (in case of overflows). Temperature channel * is not affected by overflows. */ - scan.chan[1] = cpu_to_le16(U16_MAX); - scan.chan[2] = cpu_to_le16(U16_MAX); - scan.chan[3] = cpu_to_le16(U16_MAX); + if (*indio_dev->active_scan_mask == AS73211_SCAN_MASK_ALL) { + scan.chan[1] = cpu_to_le16(U16_MAX); + scan.chan[2] = cpu_to_le16(U16_MAX); + scan.chan[3] = cpu_to_le16(U16_MAX); + } else { + scan.chan[0] = cpu_to_le16(U16_MAX); + scan.chan[1] = cpu_to_le16(U16_MAX); + scan.chan[2] = cpu_to_le16(U16_MAX); + } }
iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev)); @@ -758,6 +773,7 @@ static int as73211_probe(struct i2c_client *client) indio_dev->channels = data->spec_dev->channels; indio_dev->num_channels = data->spec_dev->num_channels; indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->available_scan_masks = as73211_scan_masks;
ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_OSR); if (ret < 0)
--- base-commit: 91e71d606356e50f238d7a87aacdee4abc427f07 change-id: 20241123-iio_memset_scan_holes-a673833ef932
Best regards,