This is a note to let you know that I've just added the patch titled
iio: buffer: make sure O_NONBLOCK is respected
to my char-misc git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git in the char-misc-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From 3da1814184582ed0faf039275a3f02e6f69944ee Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Nuno=20S=C3=A1?= nuno.sa@analog.com Date: Thu, 16 Feb 2023 11:14:51 +0100 Subject: iio: buffer: make sure O_NONBLOCK is respected MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
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@analog.com Reviewed-by: Lars-Peter Clausen lars@metafoo.de Link: https://lore.kernel.org/r/20230216101452.591805-3-nuno.sa@analog.com Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com --- drivers/iio/industrialio-buffer.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index 6340d8e1430b..a7a080bed180 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -203,21 +203,24 @@ static ssize_t iio_buffer_write(struct file *filp, const char __user *buf, 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;