RE: [PATCH 5/7] staging: comedi: don't allow write() on async command set up for "read"

[Hartley Sweeten]

On Thursday, October 30, 2014 5:43 AM, Ian Abbott wrote:
> If a Comedi asynchronous command has been set up for data transfer in
> the "read" direction on the current "write" subdevice (for those
> subdevices that support both directions), don't allow the "write" file
> operation as that would mess with the data in the comedi data buffer
> that is written 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 6805ec9..6328965 100644
> --- a/drivers/staging/comedi/comedi_fops.c
> +++ b/drivers/staging/comedi/comedi_fops.c
> @@ -2075,6 +2075,10 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
>  		retval = -EACCES;
>  		goto out;
>  	}
> +	if (!(async->cmd.flags & CMDF_WRITE)) {
> +		retval = -EINVAL;
> +		goto out;
> +	}
>  
>  	add_wait_queue(&async->wait_head, &wait);
>  	on_wait_queue = true;
> @@ -2146,6 +2150,10 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
>  				retval = -EACCES;
>  				break;
>  			}
> +			if (!(async->cmd.flags & CMDF_WRITE)) {
> +				retval = -EINVAL;
> +				break;
> +			}

Same question as with PATCH 4/7.

Is this test needed in the while () loop. Also, are the s->busy tests needed here?

>  			continue;
>  		}

Regards,
Hartley

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