Re: [PATCH v6.1 1/1] Input: Add userio module

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

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?

> +
> +	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.

-- 
Dmitry