On Fri, 2015-10-02 at 10:37 -0700, Dmitry Torokhov wrote:
> On Wed, Sep 23, 2015 at 01:54:59PM -0400, cpaul@redhat.com wrote:
> > +static int userio_device_write(struct serio *id, unsigned char
> > val)
> > +{
> > +	struct userio_device *userio = id->port_data;
> > +	unsigned long flags;
> > +
> > +	if (!userio)
> > +		return -1;
> 
> I still have the same question: how can this happen? Where do we
> reset
> port data to NULL? What happens if we set to NULL after checking?
> 

Actually David pointed out this line was not needed, somehow it still
got left in the patch. I'll send an updated version in just a minute
with the changes.

Cheers,
	Lyude
> > +
> > +	spin_lock_irqsave(&userio->buf_lock, flags);
> > +
> > +	userio->buf[userio->head] = val;
> > +	userio->head = (userio->head + 1) % USERIO_BUFSIZE;
> > +
> > +	if (userio->head == userio->tail)
> > +		dev_warn(userio_misc.this_device,
> > +			 "Buffer overflowed, userio client isn't
> > keeping up");
> > +
> > +	spin_unlock_irqrestore(&userio->buf_lock, flags);
> > +
> > +	wake_up_interruptible(&userio->waitq);
> > +
> > +	return 0;
> > +}
> 
> Thanks.
>