From: Nuno Sá <nuno.sa@xxxxxxxxxx>
commit 3da1814184582ed0faf039275a3f02e6f69944ee upstream.
For output buffers, there's no guarantee that the buffer won't be full
in the first iteration of the loop in which case we would block
independently of userspace passing O_NONBLOCK or not. Fix it by always
checking the flag before going to sleep.
While at it (and as it's a bit related), refactored the loop so that the
stop condition is 'written != n', i.e, run the loop until all data has
been copied into the IIO buffers. This makes the code a bit simpler.
Fixes: 9eeee3b0bf190 ("iio: Add output buffer support")
Signed-off-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
Reviewed-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230216101452.591805-3-nuno.sa@xxxxxxxxxx
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iio/industrialio-buffer.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -203,21 +203,24 @@ static ssize_t iio_buffer_write(struct f
break;
}
+ if (filp->f_flags & O_NONBLOCK) {
+ if (!written)
+ ret = -EAGAIN;
+ break;
+ }
+
wait_woken(&wait, TASK_INTERRUPTIBLE,
MAX_SCHEDULE_TIMEOUT);
continue;
}
ret = rb->access->write(rb, n - written, buf + written);
- if (ret == 0 && (filp->f_flags & O_NONBLOCK))
- ret = -EAGAIN;
+ if (ret < 0)
+ break;
- if (ret > 0) {
- written += ret;
- if (written != n && !(filp->f_flags & O_NONBLOCK))
- continue;
- }
- } while (ret == 0);
+ written += ret;
+
+ } while (written != n);
remove_wait_queue(&rb->pollq, &wait);
return ret < 0 ? ret : written;
