iio:kfifo_buf improve error handling in read_first_n.

These two elements were originally in the patch
iio:kfifo_buf  Take advantage of the fixed record size used in IIO
but Lars-Peter Clausen pointed out they should not have been
so here they are.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Tested-by: Lars-Peter Clausen <lars@metafoo.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/iio/kfifo_buf.c b/drivers/iio/kfifo_buf.c
index 8a6d28ce21b2..6ec763f1202a 100644
--- a/drivers/iio/kfifo_buf.c
+++ b/drivers/iio/kfifo_buf.c
@@ -108,10 +108,12 @@ static int iio_read_first_n_kfifo(struct iio_buffer *r,
         int ret, copied;
         struct iio_kfifo *kf = iio_to_kfifo(r);
 
-        if (n < r->bytes_per_datum)
+        if (n < r->bytes_per_datum || r->bytes_per_datum == 0)
                 return -EINVAL;
 
         ret = kfifo_to_user(&kf->kf, buf, n, &copied);
+        if (ret < 0)
+                return ret;
 
         return copied;
 }