Re: [PATCH 2/2] staging: comedi: cb_pcidas64: Fixed an if-statement check

[Dan Carpenter <dan.carpenter@oracle.com>]

On Tue, Jun 05, 2012 at 11:17:51AM +0300, Dimitrios Semitsoglou-Tsiapos wrote:
> On Mon, Jun 04, 2012 at 08:43:18PM -0700, Greg KH wrote:
> > On Tue, May 29, 2012 at 12:51:45AM +0300, Dimitrios Semitsoglou-Tsiapos wrote:
> > > Fixed in if-statemnt responsible for a sanity check inside the
> > > prep_ao_dma function.
> > > 
> > > Signed-off-by: Dimitrios Semitsoglou-Tsiapos <dimitrios.semitsoglou@gmail.com>
> > > ---
> > >  drivers/staging/comedi/drivers/cb_pcidas64.c |    4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/staging/comedi/drivers/cb_pcidas64.c b/drivers/staging/comedi/drivers/cb_pcidas64.c
> > > index 6f7fd99..a2e6f96 100644
> > > --- a/drivers/staging/comedi/drivers/cb_pcidas64.c
> > > +++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
> > > @@ -3392,8 +3392,8 @@ static int prep_ao_dma(struct comedi_device *dev, const struct comedi_cmd *cmd)
> > >  	num_bytes = load_ao_dma_buffer(dev, cmd);
> > >  	if (num_bytes == 0)
> > >  		return -1;
> > > -	if (num_bytes >= DMA_BUFFER_SIZE) ;
> > > -	load_ao_dma(dev, cmd);
> > > +	if (num_bytes >= DMA_BUFFER_SIZE)
> > > +		load_ao_dma(dev, cmd);
> > 
> > Are you sure about this change?  I think someone forgot to include an
> > error check here, the driver was working with this function always being
> > called, and now you only do it for the extreme case.
> > 
> > Have you checked it somehow?
> > 
> > thanks,
> > 
> > greg k-h
> You are correct. I had misread load_ao_dma's loop as a while loop.
> I'm afraid I did not have a way to test this and it does seem that it
> should *not* be included.

It's hard to say, I think your patch is probably correct.  It sort
of matches the do while loop in load_ao_dma().  But it's best if
someone could test this.

regards,
dan carpenter