As Lars pointed out, we could either return the FD vs memcpy-ing it to the
userspace data object.
However, this comment exposed a bug. We should return 0 or negative from
these ioctl() handlers. Because an ioctl() handler can also return
IIO_IOCTL_UNHANDLED (which is positive 1), which means that the ioctl()
handler doesn't support this ioctl number. Positive 1 could also be a valid
FD number in some corner cases.
The reason we did this is to be able to differentiate between an error
code and an unsupported ioctl number; for unsupported ioctl numbers, the
main loop should keep going.
Maybe we should change this to a higher negative number, to avoid such
cases when/if we add more ioctl() handlers.
Cc: Lars-Peter Clausen <lars@xxxxxxxxxx>
Fixes: f73f7f4da5818 ("iio: buffer: add ioctl() to support opening extra buffers for IIO device")
Signed-off-by: Alexandru Ardelean <aardelean@xxxxxxxxxxx>
---
drivers/iio/industrialio-buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index ee5aab9d4a23..d7a15c9bb0cd 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1442,7 +1442,7 @@ static long iio_device_buffer_getfd(struct iio_dev *indio_dev, unsigned long arg
goto error_free_ib;
}
- return fd;
+ return 0;
error_free_ib:
kfree(ib);
--
2.30.2
