On Wed, 2010-05-19 at 17:22 +0100, Ian Abbott wrote:
> For write(), any data copied to the data buffer after the previously
> set up streaming acquisition command has finished won't be used, but a
> non-empty write() does not currently return 0 (or -EPIPE on error) after
> the command has finished until the data buffer has been filled up.
> Change this behavior to return 0 (or -EPIPE) any time after the command
> has finished, without bothering to fill up the buffer with more useless
> data.
>
> Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
> ---
> drivers/staging/comedi/comedi_fops.c | 23 +++++++++++++----------
> 1 files changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
> index 158a6b2..9a26428 100644
> --- a/drivers/staging/comedi/comedi_fops.c
> +++ b/drivers/staging/comedi/comedi_fops.c
> @@ -1576,6 +1576,19 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
> while (nbytes > 0 && !retval) {
> set_current_state(TASK_INTERRUPTIBLE);
>
> + if (!(comedi_get_subdevice_runflags(s) & SRF_RUNNING)) {
> + if (count == 0) {
> + if (comedi_get_subdevice_runflags(s) &
> + SRF_ERROR) {
> + retval = -EPIPE;
> + } else {
> + retval = 0;
> + }
> + do_become_nonbusy(dev, s);
> + }
> + break;
> + }
Hi Ian.
You tend to get many tab indentations.
As this is in a while (.. && !retval) the retval = 0 is unnecessary,
so maybe something like this is better?
if (!(comedi_get_subdevice_runflags(s) & SRF_RUNNING)) {
if (count)
break;
if (comedi_get_subdevice_runflags(s) & SRF_ERROR)
retval = -EPIPE;
do_become_nonbusy(dev, s);
break;
}
Maybe a macro/function like test_runflags might be useful
to reduce the name/line length.
#define test_runflags(s, flags) \
return !!(comedi_get_subdevice_runflags(s) & flags);
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