From: Alexandru Ardelean <aardelean@deviqon.com>
To: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: jic23@kernel.org, Alexandru Ardelean <aardelean@deviqon.com>,
Lars-Peter Clausen <lars@metafoo.de>
Subject: [PATCH] iio: buffer: return 0 for buffer getfd ioctl handler
Date: Mon, 22 Mar 2021 10:41:35 +0200 [thread overview]
Message-ID: <20210322084135.17536-1-aardelean@deviqon.com> (raw)
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@metafoo.de>
Fixes: f73f7f4da5818 ("iio: buffer: add ioctl() to support opening extra buffers for IIO device")
Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
---
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
next reply other threads:[~2021-03-22 8:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 8:41 Alexandru Ardelean [this message]
2021-03-29 12:33 ` [PATCH] iio: buffer: return 0 for buffer getfd ioctl handler Jonathan Cameron
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