On Tue, Mar 24, 2015 at 12:46:21PM +0100, Gerd Hoffmann wrote:
> Hi,
>
> > > + spin_lock_irqsave(&vi->lock, flags);
> > > + while ((event = virtqueue_get_buf(vi->evt, &len)) != NULL) {
> > > + input_event(vi->idev,
> > > + le16_to_cpu(event->type),
> > > + le16_to_cpu(event->code),
> > > + le32_to_cpu(event->value));
> >
> > What happens if input layer gets an
> > unexpected event code or value?
>
> input layer checks it and ignores events not supported (according to the
> support bitmaps).
Right but support bitmaps come from host too, no?
> > > +static int virtinput_send_status(struct virtio_input *vi,
> > > + u16 type, u16 code, s32 value)
> > > +{
>
> > This means that caller will get errors if it happens to call
> > send_status at a rate that's faster than host's consumption of them.
> > To me this looks wrong.
> > Poking at input layer, it seems to simply discard errors.
> > Is it always safe to discard status updates?
>
> Typical use case is updating the leds of your keyboard. Loosing one
> update isn't the end of the world. Also that are _very_ low rate
> events, and in case that really actually happens you likely have bigger
> problems anyway ;)
Until QE opens a bug report I guess :)
OK but pls add a comment.
> > > +static void virtinput_cfg_bits(struct virtio_input *vi, int select, int subsel,
> > > + unsigned long *bits, unsigned int bitcount)
> > > +{
> > > + unsigned int bit;
> > > + size_t bytes;
> > > + u8 *virtio_bits;
> > > +
> > > + bytes = virtinput_cfg_select(vi, select, subsel);
> > > + if (!bytes)
> > > + return;
> >
> > How about limiting bytes to sizeof struct virtio_input_config->u?
>
> It's limited to 256 anyway because size is u8 in config space.
That struct is 128 bytes though.
Also, change bytes and virtinput_cfg_select to be u8 to make this
clearer?
> > > + size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_DEVIDS, 0);
> > > + if (size >= 8) {
> >
> > What does 8 mean here? Should be sizeof virtio_input_devids?
>
> Yes, fixed.
>
> > > +struct virtio_input_config {
> > > + __u8 select;
> > > + __u8 subsel;
> > > + __u8 size;
> > > + __u8 reserved;
> > > + union {
> > > + char string[128];
> > > + __u8 bitmap[128];
> >
> > I note that neither string nor bitmap are used by
> > driver. What are they in aid of?
>
> Fixed. Just sloppy coding, the name should use u.string, the bitmap
> u.bitmap, instead of just "u" (although for offsetof it doesn't make a
> difference).
>
> cheers,
> Gerd
>
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