Re: [PATCH 2/2] iio: inkern: add error case in iio_channel_get()

From: Jonathan Cameron
Date: Mon Sep 10 2012 - 05:16:30 EST

On 10/09/12 09:02, Kim, Milo wrote:
The datasheet name is defined in the IIO driver.
On the other hand, the adc_channel_label is configured in
the platform machine side.
If the datasheet name is not matched with any adc_channel_label,
the iio_channel_get() should be returned as error for preventing
using invalid IIO channel data.

Moreover, this patch detects NULL pointer dereference problem at early time.
In general, the IIO driver just accesses to any member of the iio_chan_spec
in own xxx_read_raw() function.
If the iio_chan_spec is invalid pointer, NULL dereference problem may occur
such like 'iio_chan_spec->channel' or 'iio_chan_spec->type'.
If the iio_channel_get() gets failed in the IIO consumer,
then no read_raw() operation proceeds.
I guess this is marginally cleaner, but either way it is up to the calling driver to check whether the call succeeded.

Signed-off-by: Milo(Woogyom) Kim <>
drivers/iio/inkern.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 1faa240..a5caf6b 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -136,11 +136,15 @@ struct iio_channel *iio_channel_get(const char *name, const char *channel_name)

channel->indio_dev = c->indio_dev;

- if (c->map->adc_channel_label)
+ if (c->map->adc_channel_label) {
channel->channel =

+ if (channel->channel == NULL)
+ return ERR_PTR(-ENODEV);
+ }
return channel;

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at