On Thursday, October 30, 2014 5:42 AM, Ian Abbott wrote:
> If a Comedi asynchronous command has been set up for data transfer in
> the "write" direction on the current "read" subdevice (for those
> subdevices that support both directions), don't allow the "read" file
> operation as that would mess with the data in the comedi data buffer
> that is read by the low-level comedi hardware driver.
>
> Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
> ---
> drivers/staging/comedi/comedi_fops.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
> index fef68da..6805ec9 100644
> --- a/drivers/staging/comedi/comedi_fops.c
> +++ b/drivers/staging/comedi/comedi_fops.c
> @@ -2210,6 +2210,10 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
> retval = -EACCES;
> goto out;
> }
> + if (async->cmd.flags & CMDF_WRITE) {
> + retval = -EINVAL;
> + goto out;
> + }
>
> add_wait_queue(&async->wait_head, &wait);
> while (nbytes > 0 && !retval) {
> @@ -2249,6 +2253,10 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
> retval = -EACCES;
> break;
> }
> + if (async->cmd.flags & CMDF_WRITE) {
> + retval = -EINVAL;
> + break;
> + }
Is this second test really needed in the while() loop?
For that matter, are the s->busy tests needed in the while() loop?
> continue;
> }
> m = copy_to_user(buf, async->prealloc_buf +
Regards,
Hartley
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